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Transition Metal Oxide Nanomaterials

Works Count: 40554

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This cluster of papers focuses on advanced materials and technologies for smart windows, including electrochromic and thermochromic properties of tungsten oxide and vanadium oxide, nanocrystal applications, energy efficiency, and the metal-insulator transition. The research covers a wide range of topics such as synthesis, properties, applications, and device integration for next-generation smart window technologies.

Keywords

Electrochromic; Tungsten Oxide; Vanadium Oxide; Smart Glass; Nanocrystals; Metal-Insulator Transition; Thermochromic; Energy Efficiency; Nanostructured Films; Optoelectronic

Ultrafast Switching to a Stable Hidden Quantum State in an Electronic Crystal

2014-04-10

L. Stojchevska , Igor Vaskivskyi , T. Mertelj +4 more

Exposing a Hidden State Shining intense laser light on a material can temporarily alter its properties. The effect usually subsides after a few picoseconds, unless the system is trapped in … Exposing a Hidden State Shining intense laser light on a material can temporarily alter its properties. The effect usually subsides after a few picoseconds, unless the system is trapped in a metastable state, in which case the transient period may last as long as microseconds. Stojchevska et al. (p. 177 ) observed that, following exposure to a 35-femtosecond laser pulse, the layered dichalcogenide 1T -TaS 2 entered a stable “hidden” state not present in the equilibrium phase diagram and stayed there indefinitely. The switch to the hidden state could be reversed by heat or a train of laser pulses. Because the switch alters the sample's conducting properties, the phenomenon might also lead to practical applications.

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Handbook of Inorganic Electrochromic Materials

1995-01-01

Claes-Göran Granqvist

Photoelectrochromic windows and displays

1996-10-01

Clemens Bechinger , Suzanne Ferrere , Arie Zaban +2 more

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Magnitude and Origin of the Band Gap in NiO

1984-12-10

G. A. Sawatzky , J. W. Allen

Photoemission and bremsstrahlung-isochromat-spectroscopy data on a cleaved NiO single crystal are presented and compared to band- and cluster-theory predictions. In contrast to band-theory predictions the band gap is found to … Photoemission and bremsstrahlung-isochromat-spectroscopy data on a cleaved NiO single crystal are presented and compared to band- and cluster-theory predictions. In contrast to band-theory predictions the band gap is found to be large but not determined solely by the even larger $d\ensuremath{-}d$ Coulomb interactions so that NiO is not a Mott-Hubbard insulator in the simplest sense. A large $d\ensuremath{-}d$ interaction need not prevent NiS from being a metal.

Band-gap determination from diffuse reflectance measurements of semiconductor films, and application to photoelectrochemical water-splitting

2007-06-21

Anthony B. Murphy

Optical and photoelectric properties and colour centres in thin films of tungsten oxide

1973-04-01

S. K. Deb

Abstract Thin films of Wo3 deposited on quartz substrates at room temperature have been shown to be amorphous in structure. The optical absorption spectra of the amorphous and crystalline films … Abstract Thin films of Wo3 deposited on quartz substrates at room temperature have been shown to be amorphous in structure. The optical absorption spectra of the amorphous and crystalline films have been measured in the temperature range 110° to 500°K. The fundamental absorption edge of an amorphous film occurs at 3800 Å which on crystallization moves to 4500 Å. On the high-energy side of the absorption edge several absorption peaks are resolvable in both types of film. The frequency dependence of the absorption coefficient below 104 cm−1 is described by an expression of the form K (v, T) = K 0 exp[− (β/kT) (E 0 − hv)] and above 104 cm−1 it follows a square law dependency. The temperature coefficient of the band edges was found to be − 5.0 × 10−4 eV/°K and the estimated band gaps at 0°K were found to be 3.65 and 3.27 eV for the amorphous and crystalline films, respectively. The electrical conductivity of a thin film has been measured in the temperature range 298–573°K and the activation energy was found to be 1.04 eV. Irradiation within the fundamental absorption edge gives rise to photoconductivity. Threshold wavelengths for photoconductivity were observed at 3250 and 5500 Å for the amorphous and crystalline films, respectively. A broad colour-centre band having a maximum at 9100 Å and a shoulder at 1.6 μ has been observed on irradiating the amorphous film with wavelengths shorter than 3500 Å and also on applying an electric field of ∼ 104 V./cm. The colour centre, thus formed, shows a slight bleaching with light. However, it bleaches thermally and in presence of oxidizing atmosphere. The formation of colour-centres is associated with increased electrical conductivity of the film. No colouration is observed in fully oxidized samples of WO3. An energy level diagram has been proposed to account for the optical and electrical properties as well as the colour-centre formation in WO3 films.

Electron-energy-loss spectra and the structural stability of nickel oxide: An LSDA+U study

1998-01-15

S. L. Dudarev , Gianluigi A. Botton , Sergey Y. Savrasov +2 more

We demonstrate how by taking better account of electron correlations in the $3d$ shell of metal ions in nickel oxide it is possible to improve the description of both electron … We demonstrate how by taking better account of electron correlations in the $3d$ shell of metal ions in nickel oxide it is possible to improve the description of both electron energy loss spectra and parameters characterizing the structural stability of the material compared with local spin density functional theory.

Suppression of Metal-Insulator Transition in VO 2 by Electric Field–Induced Oxygen Vacancy Formation

2013-03-21

Jaewoo Jeong , Naga Phani B. Aetukuri , Tanja Graf +3 more

Mind the Vacancies Varying the carrier density of solid-state systems to manipulate their electrical properties usually involves chemical doping, which can lead to disorder. Recently, ionic liquids have been used … Mind the Vacancies Varying the carrier density of solid-state systems to manipulate their electrical properties usually involves chemical doping, which can lead to disorder. Recently, ionic liquids have been used to form an electronic double layer on the surface of a material, tuning its carrier density by the application of an electric field. Jeong et al. (p. 1402 ) used liquid gating on VO 2 , which undergoes a metal-insulator transition close to room temperature. The liquid gating suppressed the transition to lower and lower temperatures; however, the material remained in the metallic state, even when the gating fluid was washed off. It appears that, instead of a simple electrostatic effect, the properties of VO 2 are modulated by the introduction of oxygen vacancies, an electrochemical consequence of high electric fields. The results imply that careful interpretation of liquid gating experiments in condensed matter physics is needed.

Transparent and conducting ITO films: new developments and applications

2002-05-01

C. G. Granqvist , A. Hultåker

Hydrogen-treated WO3 nanoflakes show enhanced photostability

2011-12-23

Gongming Wang , Yichuan Ling , Hanyu Wang +4 more

Here we report that photostability and photoactivity of WO3 for water oxidation can be simultaneously enhanced by controlled introduction of oxygen vacancies into WO3 in hydrogen atmosphere at elevated temperatures. … Here we report that photostability and photoactivity of WO3 for water oxidation can be simultaneously enhanced by controlled introduction of oxygen vacancies into WO3 in hydrogen atmosphere at elevated temperatures. In comparison to pristine WO3, the hydrogen-treated WO3 nanoflakes show an order of magnitude enhanced photocurrent, and more importantly, exhibit extraordinary stability for water oxidation without loss of photoactivity for at least seven hours. The enhanced photostability is attributed to the formation of substoichiometric WO3−x after hydrogen treatment, which is highly resistive to the re-oxidation and peroxo-species induced dissolution. This work constitutes the first example where WO3 can be stabilized for water oxidation in neutral medium without the need for oxygen evolution catalysts. The demonstration of electrochemically stable WO3 could open up new opportunities for WO3 based photoelectrochemical and photocatalytic applications.

<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">VO</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>: Peierls or Mott-Hubbard? A view from band theory

1994-05-23

Renata M. Wentzcovitch , Werner Schulz , Philip B. Allen

The electronic and structural properties of ${\mathrm{VO}}_{2}$ across its metal-insulator transition are studied using the local-density approximation. Band theory finds a monoclinic distorted ground state in good agreement with experiment, … The electronic and structural properties of ${\mathrm{VO}}_{2}$ across its metal-insulator transition are studied using the local-density approximation. Band theory finds a monoclinic distorted ground state in good agreement with experiment, and an almost open gap to charge excitations. Although rigid criteria for distinguishing correlated from band insulators are not available, these findings suggest that ${\mathrm{VO}}_{2}$ may be more bandlike than correlated.

The two components of the crystallographic transition in VO2

1971-11-01

John B. Goodenough

Carbon nanotubes as removable templates for metal oxide nanocomposites and nanostructures

1995-06-01

Pulickel M. Ajayan , Odile Stéphan , Ph. Redlich +1 more

Crystallographically Oriented Mesoporous WO3 Films: Synthesis, Characterization, and Applications

2001-10-06

Clara Santato , Marek Odziemkowski , M. Ulmann +1 more

Mesoporous semiconducting films consisting of preferentially orientated monoclinic-phase nanocrystals of tungsten trioxide have been prepared using a novel version of the sol-gel method. Transformations undergone by a colloidal solution of … Mesoporous semiconducting films consisting of preferentially orientated monoclinic-phase nanocrystals of tungsten trioxide have been prepared using a novel version of the sol-gel method. Transformations undergone by a colloidal solution of tungstic acid, stabilized by an organic additive such as poly(ethylene glycol) (PEG) 300, as a function of the annealing temperature have been followed by means of a confocal Raman microscope. The shape and size of WO3 nanoparticles, the porosity, and the properties of the films depend critically on preparation parameters, such as the tungstic acid/PEG ratio, the PEG chain length, and the annealing conditions. Well-crystallized WO3 films combine excellent photoresponse to the blue region of the solar spectrum, up to 500 nm, with good transparency at wavelengths larger than 550 nm. Particular applications of these nanocrystalline WO3 films include photoelectrochemical and electrochromic devices.

XPS studies of V2O5, V6O13, VO2 and V2O3

1995-04-01

J. Mendialdua , R. Casanova , Y. Barbaux

Method for Measuring Electrical Resistivity of Anisotropic Materials

1971-06-01

H. C. Montgomery

A rectangular prism with edges in principal crystal directions is prepared with electrodes on the corners of one face. Voltage-current ratios for opposite pairs of electrodes permit calculation of components … A rectangular prism with edges in principal crystal directions is prepared with electrodes on the corners of one face. Voltage-current ratios for opposite pairs of electrodes permit calculation of components of the resistivity tensor. The method can use small samples, and is best suited to materials describable by two or three tensor components. Examples are given of measurements of V2O3–Cr and oriented amorphous graphite.

Titanium Dioxide Nanomaterials for Photovoltaic Applications

2014-03-25

Yu Bai , Iván Mora‐Seró , Filippo De Angelis +2 more

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTTitanium Dioxide Nanomaterials for Photovoltaic ApplicationsYu Bai†‡, Iván Mora-Seró§, Filippo De Angelis∥, Juan Bisquert§, and Peng Wang*†View Author Information† State Key Laboratory of Polymer Physics and Chemistry, … ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTTitanium Dioxide Nanomaterials for Photovoltaic ApplicationsYu Bai†‡, Iván Mora-Seró§, Filippo De Angelis∥, Juan Bisquert§, and Peng Wang*†View Author Information† State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China‡ Institute of Chemistry and Energy Material Innovation, Academy of Fundamental Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080, China§ Photovoltaic and Optoelectronic Devices Group, Departament de Física, Universitat Jaume I, 12071 Castelló, Spain∥ Istituto CNR di Scienze e Tecnologie Molecolari, c/o Dipartimento di Chimica, Università di Perugia, via Elce di Sotto 8, I-06123 Perugia, Italy*E-mail: [email protected]Cite this: Chem. Rev. 2014, 114, 19, 10095–10130Publication Date (Web):March 25, 2014Publication History Received25 October 2013Published online25 March 2014Published inissue 8 October 2014https://pubs.acs.org/doi/10.1021/cr400606nhttps://doi.org/10.1021/cr400606nreview-articleACS PublicationsCopyright © 2014 American Chemical SocietyRequest reuse permissionsArticle Views15882Altmetric-Citations657LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Differential scanning calorimetry,Dyes and pigments,Oxides,Recombination,Solar cells Get e-Alerts

Electrochromics for smart windows: Oxide-based thin films and devices

2014-02-12

Claes G. Granqvist

Properties, requirements and possibilities of smart windows for dynamic daylight and solar energy control in buildings: A state-of-the-art review

2009-10-02

Ruben Baetens , Bjørn Petter Jelle , Arild Gustavsen

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Femtosecond Structural Dynamics in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>VO</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>during an Ultrafast Solid-Solid Phase Transition

2001-11-16

A. Cavalleri , Csaba Tóth , C. W. Siders +4 more

Femtosecond x-ray and visible pulses were used to probe structural and electronic dynamics during an optically driven, solid-solid phase transition in ${\mathrm{VO}}_{2}$. For high interband electronic excitation $(\ensuremath{\sim}5\ifmmode\times\else\texttimes\fi{}{10}^{21}{\mathrm{cm}}^{\ensuremath{-}3})$, a subpicosecond … Femtosecond x-ray and visible pulses were used to probe structural and electronic dynamics during an optically driven, solid-solid phase transition in ${\mathrm{VO}}_{2}$. For high interband electronic excitation $(\ensuremath{\sim}5\ifmmode\times\else\texttimes\fi{}{10}^{21}{\mathrm{cm}}^{\ensuremath{-}3})$, a subpicosecond transformation into the high- $T$, rutile phase of the material is observed, simultaneous with an insulator-to-metal transition. The fast time scale observed suggests that, in this regime, the structural transition may not be thermally initiated.

Mott Transition in VO 2 Revealed by Infrared Spectroscopy and Nano-Imaging

2007-12-13

M. M. Qazilbash , M. Brehm , Byung Gyu Chae +7 more

Electrons in correlated insulators are prevented from conducting by Coulomb repulsion between them. When an insulator-to-metal transition is induced in a correlated insulator by doping or heating, the resulting conducting … Electrons in correlated insulators are prevented from conducting by Coulomb repulsion between them. When an insulator-to-metal transition is induced in a correlated insulator by doping or heating, the resulting conducting state can be radically different from that characterized by free electrons in conventional metals. We report on the electronic properties of a prototypical correlated insulator vanadium dioxide in which the metallic state can be induced by increasing temperature. Scanning near-field infrared microscopy allows us to directly image nanoscale metallic puddles that appear at the onset of the insulator-to-metal transition. In combination with far-field infrared spectroscopy, the data reveal the Mott transition with divergent quasi-particle mass in the metallic puddles. The experimental approach used sets the stage for investigations of charge dynamics on the nanoscale in other inhomogeneous correlated electron systems.

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Collective bulk carrier delocalization driven by electrostatic surface charge accumulation

2012-07-01

Masaki Nakano , Keisuke Shibuya , Daisuke Okuyama +5 more

Optical Properties of V<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>between 0.25 and 5 eV

1968-08-15

H. W. Verleur , A. S. Barker , C. N. Berglund

The optical constants of V${\mathrm{O}}_{2}$ have been determined between 0.25 and 5 eV both below and above the semiconductor-metal transition temperature ${T}_{t}=340\ifmmode^\circ\else\textdegree\fi{}$K. Reflectivity and transmission spectra have been measured on … The optical constants of V${\mathrm{O}}_{2}$ have been determined between 0.25 and 5 eV both below and above the semiconductor-metal transition temperature ${T}_{t}=340\ifmmode^\circ\else\textdegree\fi{}$K. Reflectivity and transmission spectra have been measured on both single crystals and than films. The reflectivity spectra of the bulk crystals were measured with E \ensuremath{\perp} ($c$ axis) in the tetragonal phase [or \ensuremath{\perp} ($a$ axis) in the monoclinic phase], and with E parallel to these axes. While there are some differences in magnitude between the dielectric constants obtained from thin-film and single-crystal measurements, the structural features are in good agreement. Below ${T}_{t}$ there are four prominent absorption peaks centered near photon energies of 0.85, 1.3, 2.8, and 3.6 eV. Above ${T}_{t}$, metallic free-carrier absorption is observed below 2.0 eV, but the same two absorption peaks near 3 and 4 eV are present. The energy location and polarization dependence of these two higher energy peaks can be related to similar absorption peaks in rutile, and are interpreted using the rutile band structure. The results are consistent with a picture in which filled bands arising primarily from oxygen $2p$ orbitals are separated by approximately 2.5 eV from partially filled bands arising primarily from vanadium $3d$ orbitals. Transitions from the filled $2p$ bands are responsible for the high-energy peaks in the optical absorption in both the high- and low-temperature phases. In the high-temperature metallic phase, there is evidence that there is overlap among the $3d$ bands such that at least two bands are partially occupied by the extra $d$ electron per vanadium ion. In the low-temperature semiconductor phase, a band gap of approximately 0.6 eV opens up within the $3d$ bands, separating two filled bands from higher-lying empty bands. The two absorption peaks at 0.85 and 1.3 eV are due to transitions from these two filled bands.

Self‐Assembled Vanadium Pentoxide (V2O5) Hollow Microspheres from Nanorods and Their Application in Lithium‐Ion Batteries

2005-06-08

Amin Cao , Jin‐Song Hu , Han‐Pu Liang +1 more

"Hedgehog" or "nest" microspheres of V2O5 are formed when nanorods of V2O5 are synthesized in a mediated polyol process. When the concentration of the starting material is low, a nest … "Hedgehog" or "nest" microspheres of V2O5 are formed when nanorods of V2O5 are synthesized in a mediated polyol process. When the concentration of the starting material is low, a nest shape is preferred, whereas a high concentration of [V(acac)3] affords hedgehog-shaped microspheres (see picture). The V2O5 microspheres exhibit remarkable electrochemical properties when used as the cathode material in a lithium-ion battery. Self-assembled structures with highly specific morphology and novel properties are of great interest to chemists and materials scientists. As a result of rapid advancements in synthetic strategies, highly organized building blocks of metals,1 semiconductors,2 copolymers,3 organic–inorganic hybrid materials,4 and biominerals5 have been synthesized by using various methods. However, controlled organization into curved structures from rodlike building blocks remains a challenge. Such a capability is attractive to scientists not only because of its importance in understanding the concept of self-assembly with artifial building blocks but also for its great application potential.6–9 Vanadium pentoxide (V2O5) has been extensively studied as a well-known transition-metal oxide. Various nanostructures of V2O5,10 such as nanotubes, nanowires, nanofibers, nanobelts, nanorods, and mesoporous structures have already been synthesized by a variety of methods, including reverse-micelle transition, sol–gel process, hydrothermal treatment, and electrochemical deposition. Nanostructured V2O5 has potential application in the fields of lithium-ion batteries,10c,10d, 11 actuators,10f catalysis,12 and sensors.13 To our knowledge, hollow microspherical V2O5 has not been reported until now although such a structure has long been a focus of research.14 Herein, we describe a facile method to self-assemble V2O5 nanorods into microspheres. A mediated polyol process was adopted to prepare hollow microspherical V2O5, in which ethylene glycol (EG) is treated with a metal salt in the presence of poly(vinylpyrrolidone) (PVP). Such a method was previously used to obtain metal nanoparticles, nanowires (EG as a reductant),15 and oxide nanowires (EG as a ligand).16 We now present its use, for the first time, to synthesize hollow microspheres of V2O5. Using vanadium(III) acetylacetonate (acac) as the metal-ion source, we have synthesized hollow microspheres with nanorods on their surface; moreover, the morphologies of such nanorods are readily tunable. The as-prepared vanadium hollow microspheres can be calcined into crystalline V2O5 without changing their morphologies. These V2O5 products exhibit improved electrochemical properties when they are used as cathode material in lithium-ion batteries and show good application potential. Briefly, PVP was mixed with [V(acac)3] in a solution of EG at room temperature and normal pressure then heated at 140 °C for about 100 min, which led to the eventual formation of vanadium precursors with different structures. It is worth noting that PVP had a great influence on the morphologies of the synthesized vanadium precursors. In the absence of PVP, nanorods mainly form, the aspect ratios and diameters of which are tunable. Figure 1 a shows such nanorods with diameters of about 200 nm and lengths up to 2 μm at a concentration of 6 mm [V(acac)3]. The energy-disperse X-ray (EDX) spectroscopic analysis (inset in Figure 1 a) of the nanorods shows their chemical composition correlating well to that of the vanadium precursor. Upon the introduction of 0.14 mM of PVP, uniform hollow microspheres formed in large quantity, the morphology of which could be readily regulated by changing the concentration of [V(acac)3]. At a concentration of 6 mM [V(acac)3], the rods are relatively short and circle around to form the spherical shell just taking the shape of a nest (Figure 1 b). A broken sphere in the lower part of Figure 1 b clearly shows the hollow feature of the sphere. At a concentration of 18 mM [V(acac)3], these nanorods become longer and have a higher packing density as shown in Figure 1 c. At a concentration of 42 mM [V(acac)3], these nanorods eventually self-align perpendicular to the spherical surface and emanate from the center rather like the spines of a hedgehog (Figure 1 d). a) SEM image of the vanadium precursor prepared with 6 mM [V(acac)3] and no PVP. The inset shows the EDX pattern of the rod. b–d) SEM images of the microspheres synthesized with different concentrations of [V(acac)3] at 6 mM (b), 18 mM (c), and 42 mM (d), while the concentration of PVP was constant at 0.14 mM. After the preparation of the precursors, we investigated the effect of calcination on the crystallization and morphology of the hollow microspheres. Subsequent calcination at 500 °C over 2 h did not change the individual morphologies of these vanadium precursors. Figure 2 a shows a representative SEM image of a calcined V2O5 sample, which shows that the structure of the hollow microspheres was preserved. The sample was prepared under the same conditions as those applied to generate the samples shown in Figure 1 c. The following characterizations are all based on this sample unless otherwise noted. Figure 2 b shows a wide-angle XRD pattern of this calcined sample, which can be indexed as the orthogonal symmetry of V2O5 (space group: Pmmn (59), a=11.516, b=3.566, c=3.777 Å; JCPDS card no. 41–1426), thus demonstrating the presence of crystalline V2O5. The TEM image in Figure 2 c further affirms that the calcined V2O5 superstructures are indeed hollow microspheres with nanorods pointing out from the surface. The presence of nanorods can be clearly seen in Figure 2 d. In a high-resolution TEM (HRTEM) image taken from the edge of a nanorod (inset of Figure 2 d), the lattice fringes are clearly visible with a spacing of 0.581 nm, which is in good agreement with the spacing of the (200) planes of V2O5 (JCPDS card no. 41–1426). a) SEM image, b) XRD pattern, and c) low and d) high magnification TEM images of the calcinated V2O5 hollow microspheres. The inset in Figure 2 d is a high-resolution TEM (HRTEM) picture taken from the edge of a nanorod surface. Time-dependent experiments were performed to gain insight into the formation process of such vanadium precursors. Products were collected at different stages from the reaction mixture once the precipitate had began to appear in solution, and their morphologies were subjected to SEM investigation. As shown in Figure 3, when a sample was taken immediately after the formation of precipitate (t=0 min), the collected product comprised microspheres with smooth surfaces (Figure 3 a); after ten minutes, the surfaces of the samples were found to be rougher (Figure 3 b). Nanorods formed over the following 20 minutes (Figure 3 c), which were evidently very stable in solution as such their highly ordered superstructure remained unchanged with subsequent heating for over an hour (Figure 3 d). SEM images of the samples collected at different stages after the precipitate appeared in the clear solution: a) 0, b) 10, c) 30, and d) 90 min. Ethylene glycol has been established as a cross-linking reagent.16, 17 Xia and co-workers proposed that two key steps are involved in producing nanowires: 1) coordination of EG to the central metal ion to form a metal glycolate and 2) subsequent oligomerization.16 Such a mechanism may be adapted to explain the formation of rodlike vanadium precursors. The XRD pattern (see the Supporting Information) of the vanadium precursor shows its crystalline nature with characteristically strong peaks around 10°, which is a feature of the coordination and oligomerization processes in EG.16 FTIR spectra (see the Supporting Information) show the gradual displacement of the acac ligands with EG. The COH vibration at 1056 cm−1 together with the CH2 band at 2939 and 2877 cm−1 in the final product increases at the expense of the characteristically strong bands of CO in [V(acac)3] at 1566 and 1527 cm−1. This result indicates that EG has completely replaced acac in a similar way to that proposed by Xia and co-workers.16It is evident that PVP plays a completely different role to that reported in the polyol process.15, 16 The introduction of PVP is crucial in obtaining uniform hollow microspheres because of the template effect of the polymer. As the vinyl group is hydrophobic and carbonyl group is hydrophilic, PVP also functions as a surfactant in an EG solution. Indeed, hollow structures have already been synthesized with PVP as the template.18 A probable mechanism for the evolution of such structures is presented in Figure 4. PVP forms spherical micelles in EG with the carbonyl groups on the outside. The acac ligand of [V(acac)3] is gradually replaced by EG to form vanadium glycolates, which are easily adsorbed onto the micelle surface through their abundant hydroxy groups. Nanorods form and grow as the oligomerization of vanadium glycolates proceeds. These rods are flat on the surface at relatively low abundance but gradually turn and pack more tightly as the concentration of [V(acac)3] increases. Finally, they are perpendicular to the surface because of a spherical hindrance effect. Hollow spheres retain their geometry even after PVP is removed. Considering the abundant carbonyl and hydroxy groups in the system and because PVP is known to be a hydrogen-bonding acceptor,3a, 19 we believe the key factors affecting this self-assembly process are hydrogen bonding and the requirement that the "grafted" nanorods pack effectively. The exact role of PVP in the polyol process has long been an issue of debate,16, 18 and extensive work is underway towards its further clarification. Schematic illustration of the evolution of V2O5 hollow microspheres. a) Cyclic voltammograms of V2O5 microspheres obtained at a scan rate of 10 mV s−1. The first scan is indicated by curve A and after 15 cycles by curve B. b) The third charge(dash–dot line)–discharge(solid line) profile with a current rate of C/5. In the first reduction peak at 270 mV, only a fraction of the V5+ ions is reduced to V4+ ions. The remaining V5+ ions are reduced to V4+ ions in the second peak at 80 mV.11b The reverse reactions take place as indicated by the two corresponding oxidation peaks. With the electrochemical reaction, different phases of LixV2O5 are formed. From the binary phase diagram of V2O5–LixV2O5, we determined that the cathodic peaks at 80 and 270 mV correspond to the phase transformations from α-V2O5 to ε-V2O5, and ε-V2O5 to δ-V2O5, respectively.11d,11e The charge–discharge capability of the microspheres was investigated by using V2O5 as the cathode in a lithium-ion battery. Figure 5 b is the profile of a third charge–discharge cycle. The capacity was as high as 286.4 mA h g−1 while the charge–discharge efficiency was up to 97.2 % in the potential range from 2.0 to 4.0 V. These results show that V2O5 might be very good cathode material.10c, 10d, 11 The V2O5 samples with different morphologies (from nest-shaped to hedgehog-shaped) were tested for their electrochemical performances; they exhibited similar CV characteristics and had a variation of capacity in the Li-ion battery of less than 7 mA h g−1 (≈2 %). After the electrochemical investigation had been performed, the morphologies of the V2O5 samples were reinvestigated by TEM. The results showed that the structure of the hollow microspheres and nanorods remained unchanged. The correlations among structure, composition, morphology of V2O5, and its electrochemical properties in the lithium-ion battery have been well studied by other researchers.10c,10d In our system, the hollow microspheres together with the porous and rugged nanorods that have interconnected nanoparticles are favorable in reducing the diffusion distance of the solid-state lithium ion. Thus, the intercalation and extraction processes are of much higher efficiency, the kinetic performance of the lithium-ion battery is better, and therefore a higher capacity can be achieved. In summary, we have developed a mediated polyol process to synthesize V2O5 with highly ordered superstructures, in which nanoparticles interconnect to form nanorods, and these rods circle around to form hollow microspheres. The protocol represents a substantial simplification over more conventional methods such as electrostatic spray or thermal evaporation. The physical state of the nanorods on the surface can be varied by changing the concentration of [V(acac)3] and the formed microspheres can adopt different shapes that range from nest-like to hedgehog-like. The prepared V2O5 exhibits desirable electrochemical properties such as high capacity and remarkable reversibility when it is used as cathode material in a lithium-ion battery. Preparation of V2O5 hollow microspheres: In a typical synthesis, [V(acac)3] (0.3 g, 18 mm; Aldrich) and PVP (0.4 g, 0.14 mM; M̄w,=58 000; ACROS Organics) were added to ethylene glycol (48 mL; Beijing Chemical Reagent Ltd.) to give a cloudy solution. The mixture was stirred with a magnetic stirrer bar and heated to 140 °C. The cloudy mixture turned clear after 20 min and became opaque again after 70 min, indicating the formation of vanadium precursor. The solution was heated for another 30 min to ensure the formation of the composite structure before being allowed to cool to room temperature. The products were washed and separated by centrifugation–redispersion cycles with alcohol. These vanadium precursor was calcined at 500 °C for 2 h to obtain crystalline orthogonal V2O5. Characterization: Products were characterized by XRD, (Rigaku Dmax/rb diffractometer with CuKα radiation, λ=0.1542 nm, 40 kV, 100 mA), TEM (Philips TECNAI-20), SEM (Hitachi S-4300F), and by FTIR (Bruker Tensor 27). CV measurements were conducted by using an electrochemical cell with a three-electrode configuration. The working electrode was a glassy carbon disk of 3 mm in diameter, polished with Al2O3 paste, and washed ultrasonically in Millipore water. The experiment was carried out in an LiClO4–propylene carbonate (Li–PC, 1 M) solution with a standard calomel electrode (SCE) as the reference electrode and a Pt counter electrode with an EG&G instrument (model 273, Princeton Applied Research). Electrochemical discharge–charge behavior was investigated directly in coin cells assembled in an argon-filled glove box. The cell was made from a lithium anode and a cathode that was a mixture of V2O5 (80 %), graphite/carbon black (12 %), and teflon (8 %). The cathode was separated from the anode by an insulator sheet. The electrolyte reservoir was made from LiPF6 (1 m) in a mixture of ethylene carbonate/dimethyl carbonate/dimethoxy ethane 1:1:1 (w/w). Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2005/z500946_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Dynamical Singlets and Correlation-Assisted Peierls Transition in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow><mml:mi mathvariant="normal">V</mml:mi><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:math>

2005-01-18

Silke Biermann , A. I. Poteryaev , A. I. Lichtenstein +1 more

A theory of the metal-insulator transition in vanadium dioxide from the high- temperature rutile to the low- temperature monoclinic phase is proposed on the basis of cluster dynamical mean-field theory, … A theory of the metal-insulator transition in vanadium dioxide from the high- temperature rutile to the low- temperature monoclinic phase is proposed on the basis of cluster dynamical mean-field theory, in conjunction with the density functional scheme. The interplay of strong electronic Coulomb interactions and structural distortions, in particular, the dimerization of vanadium atoms in the low-temperature phase, plays a crucial role. We find that ${\mathrm{V}\mathrm{O}}_{2}$ is not a conventional Mott insulator, but that the formation of dynamical V-V singlet pairs due to strong Coulomb correlations is necessary to trigger the opening of a Peierls gap.

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Influence of postdeposition annealing on the structural and optical properties of sputtered zinc oxide film

1996-07-15

Vinay Gupta , Abhai Mansingh

The influence of postdeposition annealing on the structural and optical properties of rf sputtered insulating zinc oxide films has been investigated. The as-grown films deposited on quartz substrates were highly … The influence of postdeposition annealing on the structural and optical properties of rf sputtered insulating zinc oxide films has been investigated. The as-grown films deposited on quartz substrates were highly c-axis oriented and in a state of stress. These films become almost stress free after a postdeposition annealing treatment at 673 K for 1 h in air. Above 673 K, a process of coalescence was observed which causes major grain growth resulting in microcrack formation and surface roughness. The refractive index shows a strong frequency dispersion below the interband absorption edge. The optical dispersion data have been fitted to (1) a single oscillator model and (2) the Pikhtin–Yas’kov model. The origin of optical dispersion at different annealing temperatures has been discussed in the light of these models. A packing density of more than 99% is estimated in the film annealed at 673 K, indicating that these films are almost void free.

Synthesis and Characterization of Ion‐Exchangeable Titanate Nanotubes

2003-05-16

Xiaoming Sun , Yadong Li

Titanate nanotubes were synthesized under hydrothermal conditions. The optimized synthesis (100-180 degrees C, longer than 48 h), thermal and hydrothermal stability, ion exchangeability and consequent magnetic and optical properties of … Titanate nanotubes were synthesized under hydrothermal conditions. The optimized synthesis (100-180 degrees C, longer than 48 h), thermal and hydrothermal stability, ion exchangeability and consequent magnetic and optical properties of the titanate nanotubes were systematically studied in this paper. First, nanotubes with monodisperse pore-size distribution were prepared. The formation mechanism of the titanate nanotubes was also studied. Second, the thermal and hydrothermal stability were characterized with X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FTIR), and Raman spectroscopy. Results showed that sodium ions played a significant role in the stability of the frameworks. Third, the selective ion exchangeability was demonstrated with a series of ions. The ion substitution also enlarged the BET surface area of the titanate nanotubes to 240 m(2) x g(-1). Combination of these two features implied that these nanotubes might be functionalized by substitution of different transitional-metal ions and consequently used for selective catalysis. Magnetism, photoluminescence, and UV/Vis spectra of the substituted titanate nanotubes revealed that the magnetic and optical properties of the nanotubes were modifiable.

Theoretical Models for the Action Spectrum and the Current-Voltage Characteristics of Microporous Semiconductor Films in Photoelectrochemical Cells

1994-05-01

Sven Soedergren , Anders Hagfeldt , Jörgen Olsson +1 more

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTheoretical Models for the Action Spectrum and the Current-Voltage Characteristics of Microporous Semiconductor Films in Photoelectrochemical CellsSven Soedergren, Anders Hagfeldt, Joergen Olsson, and Sten-Eric LindquistCite this: J. … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTheoretical Models for the Action Spectrum and the Current-Voltage Characteristics of Microporous Semiconductor Films in Photoelectrochemical CellsSven Soedergren, Anders Hagfeldt, Joergen Olsson, and Sten-Eric LindquistCite this: J. Phys. Chem. 1994, 98, 21, 5552–5556Publication Date (Print):May 1, 1994Publication History Published online1 May 2002Published inissue 1 May 1994https://pubs.acs.org/doi/10.1021/j100072a023https://doi.org/10.1021/j100072a023research-articleACS PublicationsRequest reuse permissionsArticle Views3634Altmetric-Citations579LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts

Metal-insulator transition in vanadium dioxide

1975-06-01

Adam Zylbersztejn , N. F. Mott

The basic physical parameters which govern the metal-insulator transition in vanadium dioxide are determined through a review of the properties of this material. The major importance of the Hubbard intra-atomic … The basic physical parameters which govern the metal-insulator transition in vanadium dioxide are determined through a review of the properties of this material. The major importance of the Hubbard intra-atomic correlation energy in determining the insulating phase, which was already evidenced by studies of the magnetic properties of ${\mathrm{V}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x}{\mathrm{O}}_{2}$ alloys, is further demonstrated from an analysis of their electrical properties. An analysis of the magnetic susceptibility of niobium-doped V${\mathrm{O}}_{2}$ yields a picture for the current carrier in the low-temperature phase in which it is accompanied by a spin cloud (owing to Hund's-rule coupling), and has therefore an enhanced mass ($m\ensuremath{\simeq}60{m}_{0}$). Semiconducting vanadium dioxide turns out to be a borderline case for a classical band-transport description; in the alloys at high doping levels, Anderson localization with hopping transport can take place. Whereas it is shown that the insulating phase cannot be described correctly without taking into account the Hubbard correlation energy, we find that the properties of the metallic phase are mainly determined by the band structure. Metallic V${\mathrm{O}}_{2}$ is, in our view, similar to transition metals like Pt or Pd: electrons in a comparatively wide band screening out the interaction between the electrons in a narrow overlapping band. The magnetic susceptibility is described as exchange enhanced. The large density of states at the Fermi level yields a substantial contribution of the entropy of the metallic electrons to the latent heat. The crystalline distortion removes the band degeneracy so that the correlation energy becomes comparable with the band width and a metal-insulator transition takes place.

Transparent conductors as solar energy materials: A panoramic review

2007-07-05

Claes G. Granqvist

Electrochromic tungsten oxide films: Review of progress 1993–1998

2000-01-01

Claes‐Göran Granqvist

X-ray photoelectron spectroscopic studies of nickel-oxygen surfaces using oxygen and argon ion-bombardment

1974-06-01

K.S. Kim , Nicholas Winograd

Characterization of cobalt oxides studied by FT-IR, Raman, TPR and TG-MS

2008-04-30

Chih‐Wei Tang , Chen‐Bin Wang , Shu‐Hua Chien

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Electrochromic materials and devices: present and future

2002-10-14

Prakash R. Somani , S. Radhakrishnan

Layered vanadium and molybdenum oxides: batteries and electrochromics

2009-01-01

Natasha A. Chernova , Megan Roppolo , Anne C. Dillon +1 more

The layered oxides of vanadium and molybdenum have been studied for close to 40 years as possible cathode materials for lithium batteries or electrochromic systems. The highly distorted metal octahedra … The layered oxides of vanadium and molybdenum have been studied for close to 40 years as possible cathode materials for lithium batteries or electrochromic systems. The highly distorted metal octahedra naturally lead to the formation of a wide range of layer structures, which can intercalate lithium levels exceeding 300 Ah/kg. They have found continuing success in medical devices, such as pacemakers, but many challenges remain in their application in long-lived rechargeable devices. Their high-energy storage capability remains an encouragement to researchers to resolve the stability concerns of vanadium dissolution and the tendency of lithium and vanadium to mix changing the crystal structure on cycling the lithium in and out. Nanomorphologies have enabled higher reactivities to be obtained for both vanadium and molybdenum oxides, and with the latter show promise for electrochromic displays.

Strain engineering and one-dimensional organization of metal–insulator domains in single-crystal vanadium dioxide beams

2009-09-13

Jiannong Cao , Elif Ertekin , V. Srinivasan +7 more

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Oxide Electronics Utilizing Ultrafast Metal-Insulator Transitions

2011-03-02

Zheng Yang , Changhyun Ko , Shriram Ramanathan

Although phase transitions have long been a centerpiece of condensed matter materials science studies, a number of recent efforts focus on potentially exploiting the resulting functional property changes in novel … Although phase transitions have long been a centerpiece of condensed matter materials science studies, a number of recent efforts focus on potentially exploiting the resulting functional property changes in novel electronics and photonics as well as understanding emergent phenomena. This is quite timely, given a grand challenge in twenty-first-century physical sciences is related to enabling continued advances in information processing and storage beyond conventional CMOS scaling. In this brief review, we discuss synthesis of strongly correlated oxides, mechanisms of metal-insulator transitions, and exploratory electron devices that are being studied. Particular emphasis is placed on vanadium dioxide, which undergoes a sharp metal-insulator transition near room temperature at ultrafast timescales. The article begins with an introduction to metal-insulator transition in oxides, followed by a brief discussion on the mechanisms leading to the phase transition. The role of materials synthesis in influencing functional properties is discussed briefly. Recent efforts on realizing novel devices such as field effect switches, optical detectors, nonlinear circuit components, and solid-state sensors are reviewed. The article concludes with a brief discussion on future research directions that may be worth consideration.

Opportunities and challenges in science and technology of WO3 for electrochromic and related applications

2007-11-21

Satyen K. Deb

Evidence for a structurally-driven insulator-to-metal transition in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi>VO</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>: A view from the ultrafast timescale

2004-10-13

A. Cavalleri , T. Dekorsy , Henry Chong +2 more

We apply ultrafast spectroscopy to establish a time-domain hierarchy between structural and electronic effects in a strongly-correlated electron system. We discuss the case of the model system VO2, a prototypical … We apply ultrafast spectroscopy to establish a time-domain hierarchy between structural and electronic effects in a strongly-correlated electron system. We discuss the case of the model system VO2, a prototypical non-magnetic compound that exhibits cell doubling, charge localization and a metal-insulator transition below 340 K. We initiate the formation of the metallic phase by prompt hole photo-doping into the valence band of the low-T insulator. The I-M transition is however delayed with respect to hole injection, exhibiting a bottleneck timescale that corresponds to half period of the phonon connecting the two crystallographic phases. This experiment indicates that this controversial insulator may have important band-like character.

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Electrochromics for smart windows: thin films of tungsten oxide and nickel oxide, and devices based on these

2006-11-08

Gunnar A. Niklasson , Claes G. Granqvist

Electrochromic (EC) materials are able to change their optical properties, reversibly and persistently, by the application of an electrical voltage. These materials can be integrated in multilayer devices capable of … Electrochromic (EC) materials are able to change their optical properties, reversibly and persistently, by the application of an electrical voltage. These materials can be integrated in multilayer devices capable of modulating the optical transmittance between widely separated extrema. We first review the recent literature on inorganic EC materials and point out that today's research is focused on tungsten oxide (colouring under charge insertion) and nickel oxide (colouring under charge extraction). The properties of thin films of these materials are then discussed in detail with foci on recent results from two comprehensive investigations in the authors' laboratory. A logical exposition is obtained by covering, in sequence, structural features, thin film deposition (by sputtering), electronic band structure, and ion diffusion. A novel conceptual model is given for structural characteristics of amorphous W oxide films, based on notions of defects in the ideal amorphous state. It is also shown that the conduction band density of states is obtainable from simple electrochemical chronopotentiometry. Ion intercalation causes the charge-compensating electrons to enter localized states, implying that the optical absorption underlying the electrochromism can be described as ensuing from transitions between occupied and empty localized conduction band states. A fully quantitative theory of such transitions is not available, but the optical absorption can be modeled more phenomenologically as due to a superposition of transitions between different charge states of the W ions (6+, 5+, and 4+). The Ni oxide films were found to have a porous structure comprised of small grains. The data are consistent with EC coloration being a surface phenomenon, most likely confined to the outer parts of the grains. Initial electrochemical cycling was found to transform hydrated Ni oxide into hydroxide and oxy-hydroxide phases on the grain surfaces. Electrochromism in thus stabilized films is consistent with reversible changes between Ni hydroxide and oxy-hydroxide, in accordance with the Bode reaction scheme. An extension of this model is put forward to account for changes of NiO to Ni2O3. It was demonstrated that electrochromism is associated solely with proton transfer. Data on chemical diffusion coefficients are interpreted for polycrystalline W oxide and Ni oxide in terms of the lattice gas model with interaction. The later part of this review is of a more technological and applications oriented character and is based on the fact that EC devices with large optical modulation can be accomplished essentially by connecting W-oxide-based and Ni-oxide-based films through a layer serving as a pure ion conductor. Specifically, we treat methods to enhance the bleached-state transmittance by mixing the Ni oxide with other oxides characterized by wide band gaps, and we also discuss pre-assembly charge insertion and extraction by facile gas treatments of the films, as well as practical device manufacturing and device testing. Here the emphasis is on novel flexible polyester-foil-based devices. The final part deals with applications with emphasis on architectural "smart" windows capable of achieving improved indoor comfort jointly with significant energy savings due to lowered demands for space cooling. Eyewear applications are touched upon as well.

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Electrochromic Systems and the Prospects for Devices

2001-06-01

David R. Rosseinsky , Roger J. Mortimer

Many inorganic and organic materials exhibit redox states with distinct electronic (UV-vis) absorption bands. When the switching of redox states generates new or different visible region bands, the material is … Many inorganic and organic materials exhibit redox states with distinct electronic (UV-vis) absorption bands. When the switching of redox states generates new or different visible region bands, the material is electrochromic. Electrochromic materials are currently attracting much interest in academia and industry for both their fascinating spectroelectrochemical properties and their commercial applications. In this review some of the most important examples from the major classes of electrochromic materials are highlighted. Examples of their use in both prototype and commercial electrochromic devices are illustrated including car mirrors, windows and sun-roofs of cars, windows of buildings, displays (see Figure), printing, and frozen-food monitoring.

Composite Titanium Dioxide Nanomaterials

2014-07-11

Michael Dahl , Yiding Liu , Yadong Yin

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTComposite Titanium Dioxide NanomaterialsMichael Dahl†, Yiding Liu†‡, and Yadong Yin*†‡View Author Information† ‡ †Department of Chemistry and ‡Materials Science and Engineering Program, University of California at Riverside, … ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTComposite Titanium Dioxide NanomaterialsMichael Dahl†, Yiding Liu†‡, and Yadong Yin*†‡View Author Information† ‡ †Department of Chemistry and ‡Materials Science and Engineering Program, University of California at Riverside, Riverside, California 92521, United States*E-mail: [email protected]Cite this: Chem. Rev. 2014, 114, 19, 9853–9889Publication Date (Web):July 11, 2014Publication History Received3 November 2013Published online11 July 2014Published inissue 8 October 2014https://doi.org/10.1021/cr400634pCopyright © 2014 American Chemical SocietyRIGHTS & PERMISSIONSACS AuthorChoiceArticle Views28688Altmetric-Citations504LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (36 MB) Get e-AlertsSUBJECTS:Composites,Degradation,Materials,Oxides,Photocatalysis Get e-Alerts

Next-Generation Multifunctional Electrochromic Devices

2016-07-12

Guofa Cai , Jiangxin Wang , Pooi See Lee

ConspectusThe rational design and exploration of electrochromic devices will find a wide range of applications in smart windows for energy-efficient buildings, low-power displays, self-dimming rear mirrors for automobiles, electrochromic e-skins, … ConspectusThe rational design and exploration of electrochromic devices will find a wide range of applications in smart windows for energy-efficient buildings, low-power displays, self-dimming rear mirrors for automobiles, electrochromic e-skins, and so on. Electrochromic devices generally consist of multilayer structures with transparent conductors, electrochromic films, ion conductors, and ion storage films. Synthetic strategies and new materials for electrochromic films and transparent conductors, comprehensive electrochemical kinetic analysis, and novel device design are areas of active study worldwide. These are believed to be the key factors that will help to significantly improve the electrochromic performance and extend their application areas.In this Account, we present our strategies to design and fabricate electrochromic devices with high performance and multifunctionality. We first describe the synthetic strategies, in which a porous tungsten oxide (WO3) film with nearly ideal optical modulation and fast switching was prepared by a pulsed electrochemical deposition method. Multiple strategies, such as sol–gel/inkjet printing methods, hydrothermal/inkjet printing methods, and a novel hybrid transparent conductor/electrochromic layer have been developed to prepare high-performance electrochromic films. We then summarize the recent advances in transparent conductors and ion conductor layers, which play critial roles in electrochromic devices. Benefiting from the developments of soft transparent conductive substrates, highly deformable electrochromic devices that are flexible, foldable, stretchable, and wearable have been achieved. These emerging devices have great potential in applications such as soft displays, electrochromic e-skins, deformable electrochromic films, and so on. We finally present a concept of multifunctional smart glass, which can change its color to dynamically adjust the daylight and solar heat input of the building or protect the users' privacy during the daytime. Energy can also be stored in the smart windows during the daytime simultaneously and be discharged for use in the evening.These results reveal that the electrochromic devices have potential applications in a wide range of areas. We hope that this Account will promote further efforts toward fundamental research on electrochromic materials and the development of new multifunctional electrochromic devices to meet the growing demands for next-generation electronic systems.

Infrared Regulating Smart Window Based on Organic Materials

2017-03-02

Hitesh Khandelwal , Albertus P. H. J. Schenning , Michael G. Debije

Windows are vital elements in the built environment that have a large impact on the energy consumption in indoor spaces, affecting heating and cooling and artificial lighting requirements. Moreover, they … Windows are vital elements in the built environment that have a large impact on the energy consumption in indoor spaces, affecting heating and cooling and artificial lighting requirements. Moreover, they play an important role in sustaining human health and well‐being. In this review, we discuss the next generation of smart windows based on organic materials which can change their properties by reflecting or transmitting excess solar energy (infrared radiation) in such a way that comfortable indoor temperatures can be maintained throughout the year. Moreover, we place emphasis on windows that maintain transparency in the visible region so that additional energy is not required to retain natural illumination. We discuss a number of ways to fabricate windows which remain as permanent infrared control elements throughout the year as well as windows which can alter transmission properties in presence of external stimuli like electric fields, temperature and incident light intensity. We also show the potential impact of these windows on energy saving in different climate conditions.

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Thermochromic VO2 for Energy-Efficient Smart Windows

2018-07-20

Yuanyuan Cui , Yujie Ke , Chang Liu +7 more

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Three‐Dimensional Battery Architectures

2004-11-23

Jeffrey W. Long , Bruce Dunn , Debra R. Rolison +1 more

Abstract For Abstract see ChemInform Abstract in Full Text. Abstract For Abstract see ChemInform Abstract in Full Text.

Smart Windows: Electro‐, Thermo‐, Mechano‐, Photochromics, and Beyond

2019-09-05

Yujie Ke , Jingwei Chen , Gaojian Lin +5 more

Abstract A smart window that dynamically modulates light transmittance is crucial for building energy efficiently, and promising for on‐demand optical devices. The rapid development of technology brings out different categories … Abstract A smart window that dynamically modulates light transmittance is crucial for building energy efficiently, and promising for on‐demand optical devices. The rapid development of technology brings out different categories that have fundamentally different transmittance modulation mechanisms, including the electro‐, thermo‐, mechano‐, and photochromic smart windows. In this review, recent progress in smart windows of each category is overviewed. The strategies for each smart window are outlined with particular focus on functional materials, device design, and performance enhancement. The advantages and disadvantages of each category are summarized, followed by a discussion of emerging technologies such as dual stimuli triggered smart window and integrated devices toward multifunctionality. These multifunctional devices combine smart window technology with, for example, solar cells, triboelectric nanogenerators, actuators, energy storage devices, and electrothermal devices. Lastly, a perspective is provided on the future development of smart windows.

Metal-insulator transitions

1973-09-01

N. F. Mott

Abstract The valence and conduction bands in semi-conductors normally owe their properties to their crystal structures. Sometimes changes in pressure or composition in mixed crystals can lead to an overlap … Abstract The valence and conduction bands in semi-conductors normally owe their properties to their crystal structures. Sometimes changes in pressure or composition in mixed crystals can lead to an overlap between these bands, which results in a transition to metallic behaviour. Repulsion between electrons can also lead to the formation of two bands, which may or may not overlap; again metal-insulator transitions can occur. The most important and controversial question about these transitions is whether they are accompanied by a discontinuous change in the density of current carriers; the evidence for and against this is described. Applications are to vanadium trioxide and highly doped silicon and germanium.

Raman spectroscopy of molybdenum oxides

2002-01-31

Martin Philipp Dieterle , G. Weinberg , Gerhard Mestl

MoO3−x samples were prepared under different temperature and gas atmosphere conditions. The samples, which are all of the crystallographic MoO3 structure, have been investigated by XRD, SEM, diffuse reflection (DR) … MoO3−x samples were prepared under different temperature and gas atmosphere conditions. The samples, which are all of the crystallographic MoO3 structure, have been investigated by XRD, SEM, diffuse reflection (DR) UV/VIS and Raman spectroscopies to characterize their properties as a function of the different concentrations of oxygen vacancies. The different preparation conditions led to differences in the concentration of oxygen vacancies as well as primary crystallite sizes and morphologies. The UV/VIS spectra of the MoO3−x samples were deconvoluted into Gaussian bands attributed to ligand to metal charge transfer (LMCT), d–d transitions, and intervalence charge transfer (IVCT) transitions of [Mo5+O5] and [Mo5+O6] defect centers. The IVCT band positions at 2 eV were used to determine the sample oxygen stoichiometries. A resonance Raman enhancement was observed for the MoO3−x samples and explained by resonant coupling to the electronic absorption of the type [Mo5+O5]–[Mo6+O6] → [Mo6+O5]–[Mo5+O6] at 2.03 eV. A linear correlation was found between the Raman band intensity ratios I285/I295 and the sample oxygen/metal ratio, and hence this Raman band intensity ratio can be used to determine the oxygen stoichiometry of MoO3−x. The integral intensity of the Raman band at 823 cm−1 was also found to depend on the oxygen stoichiometry. These observed changes of the integral Raman intensities of the band at 823 cm−1 are explained by the interplay of a resonant enhanced Raman scattering and changes of the positions of the IVCT transition to which the resonant Raman scattering is coupled. The intensity ratio of the translational Raman bands at 117 and 130 cm−1, on the other hand, was shown to be a function of the primary crystallite size. The observed resonance Raman effect is discussed in the frame of in situ Raman characterization of operating Mo-based catalysts.

Unlocking the versatility of V2O5 thin films for next-generation batteries: A binder-free approach

2025-06-25

Ananya Bansal , Pramod Kumar , Kushagra Bharadwaj +2 more | Journal of Power Sources

Role of surface oxygen-deficiency on optical and charge storage capacity of frustrated cerium doped zirconium oxides nanoparticles

2025-06-24

Palani Periyasamy , Santhosh Sacratees , Bakkiyaraj Ramanujam +2 more | Materials Science and Engineering B

Mesoporous Amorphous High-Entropy Oxide Films: Unlocking Enhanced Redox Activity

2025-06-24

Qingju Wang , Meijia Li , Kevin M. Siniard +7 more | ACS Catalysis

Thickness-dependent microstructure and metal-insulator transition in vanadium dioxide thin films grown by pulsed laser deposition

2025-06-24

Yong Wook Lee , Bong-Jun Kim , Giwan Seo | Japanese Journal of Applied Physics

Abstract Vanadium dioxide (VO 2 ) thin films with thicknesses of 30, 60, 100, and 230 nm were grown on c-plane sapphire substrates using pulsed laser deposition (PLD). To explore … Abstract Vanadium dioxide (VO 2 ) thin films with thicknesses of 30, 60, 100, and 230 nm were grown on c-plane sapphire substrates using pulsed laser deposition (PLD). To explore the relationship between film thickness and metal-insulator transition behavior, we investigated the microstructural and electrical properties of the VO 2 films. X-ray diffraction (XRD), electron spectroscopy for chemical analysis (ESCA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrical resistance measurements were performed to analyze the fabricated films. XRD patterns confirmed the phase composition of the VO 2 films, while TEM images revealed the epitaxial relationship between the VO 2 films and the c-plane sapphire substrates. Notably, both grain size and transition magnitude near 68°C in the resistivity-temperature (R-T) curve increased with film thickness, highlighting the critical role of film thickness in the electrical characteristics of two-terminal VO 2 -based devices.

Tunable 3D Aerosol Jet Printing of Low‐Power Redox‐Gated Transistors with Multicomponent Inks

2025-06-24

Andrew Erwin , Shiyu Hu , Hua Zhou +6 more | Advanced Materials Technologies

Abstract Printed hybrid electronics (PHE) offer a promising alternative for microelectronics fabrication, addressing some limitations of traditional subtractive manufacturing. Despite the versatility of PHE, particularly in the customization of printing … Abstract Printed hybrid electronics (PHE) offer a promising alternative for microelectronics fabrication, addressing some limitations of traditional subtractive manufacturing. Despite the versatility of PHE, particularly in the customization of printing inks, these devices have not yet matched the performance of silicon‐based electronics due to challenges in gating mechanisms and operational stability. However, the potential of low‐voltage redox‐gating to achieve significant carrier modulations in correlated metal oxides remains unexplored in PHE. This study systematically investigates vanadium dioxide (VO 2 ) nanoparticles and redox inks, linking their organization in solution to their morphology, phase state, and properties in solid films and multilayered structures. Using an aerosol jet printer (AJP), a solid‐state VO 2 transistor is fabricated, operating at just 0.4 V gating voltage. The printed VO 2 films demonstrate redox‐modulated conductivity and consistent transistor behavior. The solid‐state redox gating materials also provide long‐term stability, with the device maintaining performance over 6000 cycles without degradation. These results highlight the potential of redox gating to enhance the application of functional nanoparticles in printed hybrid microelectronics, especially for flexible, low‐voltage, and energy‐efficient devices.

Solar power generation performance of MoO2/Mo4O11 photothermal nanomaterials

2025-06-24

Xu Zhao , Yi Liu , L. S. CHEN +3 more | Solar Energy Materials and Solar Cells

Advancements in Electrochromic Technology for Multifunctional Flexible Devices

2025-06-23

Alice Marciel , Joel Borges , Luiz Pereira +2 more | Materials

The design and investigation of electrochromic devices have advanced significantly, including distinct applications such as self-charged smart windows, aerospace interactive windows, low power flexible and ecofriendly displays, automatic dimming rearview, … The design and investigation of electrochromic devices have advanced significantly, including distinct applications such as self-charged smart windows, aerospace interactive windows, low power flexible and ecofriendly displays, automatic dimming rearview, wearable smart textiles, military and civilian camouflage systems, electrochromic sensors, among others. Although significant progress has been made in related fields, achieving the full potential of electrochromic devices to meet the standards of maturity and practical applications remains a persistent challenge. Electrochromic devices are typically multilayered structures that can be designed as either rigid or flexible systems, depending on the type of substrate employed. Conventional electrochromic devices comprise layered structures that include transparent electrodes, electrochromic materials, ionic conductors, and ion storage materials. On the other hand, multifunctional systems integrate bifunctional materials or distinct functional layers to simultaneously achieve optical modulation and additional capabilities such as energy storage. The development of advanced materials, comprehensive electrochemical kinetic analysis, the optimization and advancement of process techniques and deposition methods, and innovative device designs are active areas of extensive global research. This review focuses on the recent advances in multifunctional electrochromic materials and devices with particular emphasis on the integration of electrochromic technology with other functional technologies. It further identifies current challenges, proposes potential solutions, and outlines future research directions focused on advancing this technology in both niche and scalable applications.

A Thermochromic Hydrated Ionic Polymer with an Adjustable Transition Temperature for Smart Windows and Temperature Monitoring

2025-06-23

Huaiyuan Wang , Qi Tao , Jie Wang +7 more | ACS Applied Materials & Interfaces

Thermochromic materials with customizable transition temperatures are essential for energy-efficient, smart windows and temperature-monitoring applications. This study presents a hydrated ionic polymer featuring Ni2+ as the central ion, where reversible … Thermochromic materials with customizable transition temperatures are essential for energy-efficient, smart windows and temperature-monitoring applications. This study presents a hydrated ionic polymer featuring Ni2+ as the central ion, where reversible transitions between octahedral and tetrahedral coordination enable tunable light absorption. By adjustment of the polyvinylpyrrolidone (PVP)/poly(vinyl alcohol) (PVA) ratio, the hydroxyl content is precisely controlled, achieving a transition temperature range of 30-50 °C. The material exhibits a solar modulation of 8-23% and visible-light modulation of 10-39%, with no phase separation during operation. A two-step ligand exchange mechanism is identified: at low temperatures, H2O coordinates with Ni2+, forming a transparent octahedral structure. As the temperature rises, water desorbs and Cl- partially replaces H2O, producing a blue tetrahedral structure. Further heating triggers -OH dissociation, allowing more Cl- coordination, deepening the blue color. Molecular dynamics simulations reveal that the PVP/PVA ratio controls water diffusion and hydrogen bonding. Practical tests demonstrate that this polymer reduces solar-exposed temperatures by 10 °C in smart windows and serves as an effective temperature-monitoring label with excellent cycling stability over 100 cycles. This study presents a new perspective for designing thermochromic materials with customizable properties, offering new insights for energy-saving and sensing applications.

V2O9Te2 Nanorods for Broadband Visible Light Photoresponse and NLO Applications: An Experimental and Computational Approach

2025-06-23

Prabhukrupa C. Kumar , Jagadish Kumar , C. Sripan +1 more | ACS Applied Electronic Materials

Spontaneous emission controlled by the twisted α-MoO3 bilayers

2025-06-23

Shuting Fu , Yong-qiang Guo , Tongbiao Wang +2 more | Optics & Laser Technology

Pulse laser deposition prepared tin(IV) oxide thin films: effects of gamma radiation doses on their structural and optical characteristics

2025-06-22

Noha H. Harb , Hiba Al-Hameed , Baydaa Taher Sih +1 more | Phosphorus, sulfur, and silicon and the related elements

Synthesis and Characterization of Twin Barrel-Like Tungsten Trioxide Obtained by Hydrothermal Treatment

2025-06-21

S Amokrane , Fahim Hamidouche , Amar Irekti +4 more | Russian Journal of Inorganic Chemistry

Molybdenum‐Doped Nickel Oxide as an Advanced Ion Storage Layer for Highly Stable and Durable Flexible Electrochromic Devices

2025-06-20

Chang‐Shin Park , Kwang‐Mo Kang , Seunghoon Park +5 more | Advanced Optical Materials

Abstract Electrochromic (EC) smart windows, typically consisting of a monolithic transparent conductive oxide (TCO), an EC layer, an electrolyte, and an ion storage layer are promising technologies for improving energy … Abstract Electrochromic (EC) smart windows, typically consisting of a monolithic transparent conductive oxide (TCO), an EC layer, an electrolyte, and an ion storage layer are promising technologies for improving energy efficiency, enhancing environmental sustainability, and regulating solar heat gain, thereby supporting occupant‐centric reductions in carbon emissions. However, the conventional nickel oxide (NiO) ion‐storage layer, faces significant challenges such as rapid cycling degradation and limited mechanical flexibility, hindering its application in flexible devices. In this study, a highly stable and flexible molybdenum‐doped nickel oxide (Mo‐doped NiO, MNO) ion‐storage layer deposited on a polyethylene terephthalate (PET) substrate coated with a TCO layer of indium gallium titanium oxide (IGTO) using a co‐sputtering technique is presented. The MNO thin film exhibits excellent EC performance, transitioning from an initial dark brown state to a transparent state upon applied voltage. The electrical properties of the MNO film exhibits enhanced EC performance compared to pristine NiO. Furthermore, the MNO film demonstrates superior cycling stability, maintaining its performance over 500 operational EC cycles. It also retain electrical stability after inner and outer bending, exhibiting negligible changes in resistance even after 10,000 cycles. A potential Mo‐doping mechanism to explain the enhanced stability of the MNO‐based flexible EC devices is proposed. These findings highlight the potential of MNO as a superior alternative to conventional NiO for advanced EC technology and smart windows.

An Optical Date Flip-Flop Based on the Dynamic Coding of a Layered VO2 Metastructure

2025-06-20

Na Pei , Zhicheng Xu , Jiayuan Zhang +2 more | Photonics

A vanadium dioxide (VO2)-based layered metastructure is proposed that enables dynamic optical encoding in the range of 15.5 GHz to 16 GHz through synergistic temperature and magnetic field modulation. By … A vanadium dioxide (VO2)-based layered metastructure is proposed that enables dynamic optical encoding in the range of 15.5 GHz to 16 GHz through synergistic temperature and magnetic field modulation. By utilizing sequential temperature control, an optical date flip-flop (DFF) functionality can be achieved. The VO2 component of the metastructure exhibits an insulator-to-metal phase transition under thermal regulation, accompanied by significant changes in its optical properties. Furthermore, by optimizing the sequential temperature-control strategy, an optical DFF is successfully implemented whose output state can be dynamically controlled by the data input (D), timing control port (T), and state control port (B). A novel technical approach is provided for programmable photonic devices, dynamic optical information storage, and optical computing systems.

π‐Extended Viologen‐Based Lyotropic Chromonic Liquid Crystal Reactive Mesogen: Uniaxial Orientation and Photopolymerization for Transmittance and Color Controllable Electrochromic Smart Glass

2025-06-20

Huan Huu Pham , Minwoo Rim , Youngjae Wi +7 more | Advanced Materials

Abstract To advance the development of an electrochromic (EC) smart glass, a π ‐extended viologen‐based lyotropic chromonic liquid crystal ( π V‐LCLC) reactive mesogen (RM) is newly designed and successfully … Abstract To advance the development of an electrochromic (EC) smart glass, a π ‐extended viologen‐based lyotropic chromonic liquid crystal ( π V‐LCLC) reactive mesogen (RM) is newly designed and successfully synthesized in this study. By extending the π ‐conjugation length of viologen, the π V‐LCLC RM forms a stable LCLC phase at room temperature and retains its chemical integrity during the EC reactions, exhibiting reversible transitions across three redox states: dication (D), cation‐radical (C), and neutral (N). A uniaxially oriented nanostructure is constructed on the macroscopic scale through shear‐coating and molecular self‐assembly. Subsequent photopolymerization of the uniaxially oriented π V‐LCLC film significantly enhances its mechanical and chemical stability while enabling polarization‐dependent transmittance and distinct color transitions. This newly developed π V‐LCLC RM facilitates the fabrication of energy‐efficient EC optical devices with tunable transmittance and multicolor modulation, and it is operable at a low voltage of 2.5 V.

Low-Cost Thermoelectric Ink Painting of p-BST and n-BS for Power Generation Applications

2025-06-19

Surasak Ruamruk , Bralee Chayasombat , Athorn Vora–ud +4 more | Journal of Electronic Materials

Synergistic Structural-Compositional Modification of V2O5/C Films for Enhanced Multicolor Electrochromic Devices

2025-06-19

Xiaodan Guo , Qing Sui , Ying Lv +5 more | The Journal of Physical Chemistry Letters

The color variations of electrochromic materials originate from the redox reaction triggered by the coinjection of electrons and ions under an applied electric field. Hence, the performance of electrochromic materials … The color variations of electrochromic materials originate from the redox reaction triggered by the coinjection of electrons and ions under an applied electric field. Hence, the performance of electrochromic materials is highly dependent on the ion-electron transport process. However, the simultaneous realization of efficient ion and electron transport remains challenging. Herein, a porous V2O5/C electrochromic film with improved ion/electron transport rates was constructed through a dual structure-composition synergistic strategy. The porous structure of the film was optimized by a facile and economic plasma treatment technology due to the easily etched organic components introduced in the precursor. An optimized small-size pore structure results in outstanding electrolyte affinity and shorter ion transport paths. Furthermore, the residual carbon during the annealing process enhances the conductivity of the material, promoting electron transport. Benefiting from the optimized structure and composition, the plasma-treated V2O5/C film realizes superior ion and electron transport during electrochromic redox reactions. Therefore, the electrochromic performance of the film is significantly improved (18.4% faster switching and 51.9% greater optical modulation than unplasma-treated films), showing promising applications in smart windows and information displays. Such a simple and economical strategy for simultaneously enhancing ion/electron transport kinetics would offer a distinctive pathway for other metal oxide-based electrochemical materials.

Avaliação dos efeitos do tratamento térmico de têmpera no aço hadfield com resfriamento em água e óleo: Estudo com dente de caçamba reaproveitado

2025-06-19

Daniel Chiongo Tchicusse | Research Society and Development

Este artigo tem o objetivo de apresentar a investigação e resultados dos efeitos dos tratamentos térmicos de têmpera no aço manganês austenítico, visando melhorar suas propriedades mecânicas, particularmente a dureza … Este artigo tem o objetivo de apresentar a investigação e resultados dos efeitos dos tratamentos térmicos de têmpera no aço manganês austenítico, visando melhorar suas propriedades mecânicas, particularmente a dureza e a tenacidade, proporcionando mais tempo de vida útil e uma redução nos custos operacionais. Entretanto, o aço manganês é amplamente utilizado em ambientes de alta abrasão devido à sua excelente resistência ao desgaste, mas suas propriedades podem ser otimizadas por meio de tratamentos térmicos adequados. Para alcançar esse objetivo, os corpos de prova de aço manganês foram submetidas a um processo de têmpera a 1100°C com um tempo de permanência no interior do forno de até 1 hora. No entanto, os meios de resfriamento utilizado no processo foram água e óleo. Os resultados mostraram um aumento significativo na dureza após a têmpera com resfriamento a água, e uma redução na têmpera em óleo. As conclusões desta investigação indicam que a têmpera em água é um tratamento térmico eficaz para melhorar a dureza do aço Hadfield, aumentando o tempo de vida útil do material.

Electrochemical Performance Enhancement Mechanism of CTMS Modulating on LLZTO/PEO Composite Solid Electrolyte Interface

2025-06-19

Qian Liu , Jinghua Yin , Jialong Shen +2 more | Journal of Alloys and Compounds

Properties of rich-Nae effect and reversible oxygen redox with a complete solid-solution sodium-storage behavior

2025-06-18

Wei Zhao , Shaohua Luo , Yi-Cheng Lin +7 more | Chemical Engineering Journal

Window view clarity evaluation in electrochromic glazings

2025-06-18

Peiman Pilechiha , Nasim Goli Baghmahyari , Farhad Barahimi | Energy and Buildings

Synthesis of pure V2O5 and V–Mo mixed oxide nanoparticles and their adsorption activity

2025-06-18

Vishva Jain , Santilata Sahoo , Ajay D. Zanpadiya +1 more | International Journal of Modern Physics B

Vanadium pentoxide (V 2 O[Formula: see text] and Vanadium–Molybdenum (V–Mo) mixed oxide nanoparticles are synthesized at 500 ∘ C using a surfactant-free method, with an increase in the atomic percentage … Vanadium pentoxide (V 2 O[Formula: see text] and Vanadium–Molybdenum (V–Mo) mixed oxide nanoparticles are synthesized at 500 ∘ C using a surfactant-free method, with an increase in the atomic percentage of Mo ([Formula: see text], 20%, 30% and 40%) to V. X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM), Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) were used to characterize the synthesized samples. By using the Debye Scherrer technique and WH plot calculations, the average crystallite sizes and lattice strain assessed from XRD data were found to be almost comparable. SEM detects agglomerated nanoparticle morphology in both pure V 2 O 5 and V–Mo mixed oxide nanoparticles. EDAX confirms the prepared sample’s purity and the presence of its constituent parts. According to diffuse reflectance spectroscopy, the energy band gap was reduced as the amount of Mo in mixed oxide V–Mo nanoparticles rose. The strength of the peak diminishes as the amount of Mo in mixed oxide V–Mo increases on the Raman analysis graph. The presence of V–O and Mo–O functional groups, as well as their formation of pure V 2 O 5 and V–Mo mixed oxide nanoparticles, was confirmed by the FT-IR spectra. Adsorption activity was performed for the dye degradation of methylene blue by pure V 2 O 5 and V–Mo mixed oxide nanoparticles; the percentage of dye degradation removal increased as Mo concentration increased in the V–Mo mixed oxide nanoparticles.

Insights into structural, Dielectric, and magnetic properties of Indium oxide composites

2025-06-18

Zainab Bashir , Zohra Nazir Kayani , Hina Nazli +3 more | Solid State Communications

High-performance electrochromic aqueous batteries enabled by Li4Ti5O12 anodes: Bridging Electrochromism and efficient energy storage

2025-06-18

Jinxiao Wang , Zhisheng Wu , Zhen Dong Lian +5 more | Journal of Colloid and Interface Science

Real-space Observation of Metal–Insulator Transition of Individual Anisotropic Nanodomain in VO2/TiO2(110) Thin Films

2025-06-18

Kyungmin Kim , Linfeng Hou , Masayuki Abe +1 more | e-Journal of Surface Science and Nanotechnology

A Bifunctional Electrochromic/Electrofluorochromic Ionic Liquid Enables Displayable Smart Windows with High Energy Efficiency

2025-06-18

Ruonan Huang , Ningzhi Cao , Garrick Gu +2 more | Advanced Functional Materials

Abstract The integration of display functionality into electrochromic (EC) smart windows offers a promising avenue for enhancing energy efficiency, urban aesthetics, and public interaction in modern high‐rise buildings. However, their … Abstract The integration of display functionality into electrochromic (EC) smart windows offers a promising avenue for enhancing energy efficiency, urban aesthetics, and public interaction in modern high‐rise buildings. However, their development has been impeded by the limited choice of electroactive materials with effective solar spectral modulation, high optical contrast, and visible fluorescence. In this study, a bifunctional electrochromic/electrofluorochromic (EC/EFC) ionic liquid containing triphenylamine, carbazole, and imidazole moieties (EEIL) is designed and synthesized. Displayable smart windows are constructed using a pixel confinement strategy and exhibits impressive programmed reflective/emissive dual‐modal display performance with high optical contrast across diverse lighting environments. Notably, the device exhibits exceptional optical/thermal management characteristics within the solar radiation spectrum range, achieving an energy efficiency of 13.44% of the total energy consumption. The synergistic integration of dual‐modal display capabilities with efficient optical and thermal management has contributed to the development of sustainable and interactive urban environments.

PVP-Engineered WO3/TiO2 Heterostructures for High-Performance Electrochromic Applications with Enhanced Optical Modulation and Stability

2025-06-17

Pritam J. Morankar , Rutuja U. Amate , Mrunal Bhosale +1 more | Polymers

In response to escalating global energy demands and environmental challenges, electrochromic (EC) smart windows have emerged as a transformative technology for adaptive solar modulation. Herein, we report the rational design … In response to escalating global energy demands and environmental challenges, electrochromic (EC) smart windows have emerged as a transformative technology for adaptive solar modulation. Herein, we report the rational design and fabrication of a bilayer WO3/TiO2 heterostructure via a synergistic two-step strategy involving the electrochemical deposition of amorphous WO3 and the controlled hydrothermal crystallization of TiO2. Structural and morphological analyses confirm the formation of phase-pure heterostructures with a tunable TiO2 crystallinity governed by reaction time. The optimized WTi-5 configuration exhibits a hierarchically organized nanostructure that couples the fast ion intercalation dynamics of amorphous WO3 with the interfacial stability and electrochemical modulation capability of crystalline TiO2. Electrochromic characterization reveals pronounced redox activity, a high charge reversibility (98.48%), and superior coloration efficiency (128.93 cm2/C). Optical analysis confirms an exceptional transmittance modulation (ΔT = 82.16% at 600 nm) and rapid switching kinetics (coloration/bleaching times of 15.4 s and 6.2 s, respectively). A large-area EC device constructed with the WTi-5 electrode delivers durable performance, with only a 3.13% degradation over extended cycling. This study establishes interface-engineered WO3/TiO2 bilayers as a scalable platform for next-generation smart windows, highlighting the pivotal role of a heterostructure design in uniting a high contrast, speed, and longevity within a single EC architecture.

High-Performance Electrochromic Energy Storage Devices Based on Hexagonal WO3 and SnO2/PB Composite Films

2025-06-17

Yi Wang , Zilong Zhang , Ze Wang +3 more | Materials

Electrochromic devices have garnered significant interest owing to their promising applications in smart multifunctional electrochromic energy storage systems (EESDs) and their emerging next-generation electronic technologies. Tungsten oxide (WO3), possessing both … Electrochromic devices have garnered significant interest owing to their promising applications in smart multifunctional electrochromic energy storage systems (EESDs) and their emerging next-generation electronic technologies. Tungsten oxide (WO3), possessing both electrochromic and pseudocapacitive characteristics, offers great potential for developing multifunctional devices with enhanced performance. However, achieving an efficient and straightforward synthesis of WO3 electrochromic films, while simultaneously ensuring high coloration efficiency and energy storage capability, remains a significant challenge. In this work, a low-temperature hydrothermal approach is employed to directly grow hexagonal-phase WO3 films on FTO substrates. This process utilizes sorbitol to promote nucleation and rubidium sulfate to regulate crystal growth, enabling a one-step in situ fabrication strategy. To complement the high-performance WO3 cathode, a composite PB/SnO2 film was designed as the anode, offering improved electrochromic properties and enhanced stability. The assembled EESD exhibited fast bleaching/coloration response and a high coloration efficiency of 101.2 cm2 C-1. Furthermore, it exhibited a clear and reversible change in optical properties, shifting from a transparent state to a deep blue color, with a transmittance modulation reaching 81.47%.

Influence of Compactness and Crystallinity on Hole Transfer Ability of Nickel Oxide Layer in Modal Coupling Regime

2025-06-17

Tomoya Oshikiri , Takashi Katsurahara , Naoyoshi Kubota +7 more | Chemistry - A European Journal

This study investigates how structural properties influence the hole migration behavior of nickel oxide (NiOx) by evaluating its photoelectrochemical performance. Two fabrication methods were employed for preparing NiOx layers. One … This study investigates how structural properties influence the hole migration behavior of nickel oxide (NiOx) by evaluating its photoelectrochemical performance. Two fabrication methods were employed for preparing NiOx layers. One is a sol‐gel wet process, which allows wide‐area coating without the need for specialized equipment. The other is atomic layer deposition, which enables uniform and conformal coverage on three‐dimensional surfaces with the compact oxide layer by leveraging a self‐limiting, layer‐by‐layer growth mechanism. Our findings reveal that both crystallinity and compactness significantly affect the hole transport capability of NiOx layers. We further integrated the NiOx layer as a hole transport layer in an Au‐NPs/NiOx/Pt‐film photocathode operating under a modal coupling regime. This photocathode exhibited cathodic photocurrent at wavelengths below 800 nm, with a maximum incident photon‐to‐current efficiency of 0.16% at 600 nm. These results demonstrate that not only the hole injection process but also hole migration properties of the NiOx layer influence the charge separation under modal coupling conditions.

High-frequency electrical behavior in V3O5 thin films

2025-06-17

Camilo Verbel , Alexander Bartenev , Manuel Lozano +3 more | Journal of Applied Physics

Vanadium oxides are known for their metal–insulator transition (MIT), with V3O5 being notable for its transition temperature exceeding room temperature. At about 430 K, this material shows a change in … Vanadium oxides are known for their metal–insulator transition (MIT), with V3O5 being notable for its transition temperature exceeding room temperature. At about 430 K, this material shows a change in crystal symmetry accompanied with one order of magnitude increase in its electrical conductivity and alterations in its optical properties. Although the property changes during the MIT in V3O5 are less pronounced than those observed in VO2, its transition temperature is 90 K higher, making it appealing for applications requiring elevated temperatures. In this article, the high-frequency characteristics were determined in a V3O5 two-terminal device in the range from 5 to 35 GHz. The S-parameters showed that the return loss at room temperature was close to −1.5 dB, and the isolation between ports was approximately −50 dB. At temperatures above the metal–insulator transition, the isolation decreased to around −40 dB at 35 GHz. For S11 and S22, similar behavior was observed at room temperature, with a notable change in the S-parameter phase of the device. This behavior suggests that V3O5 may function well as a capacitor because the considerable change in phase could control the flow of electrical signals in devices. This property also may be used for matching purposes, especially considering its response to temperature changes. Additionally, conductivity calculation from S-parameters shows a decrease of approximately two orders of magnitude at 500 K and one order of magnitude at 300 K compared to DC values. These findings highlight V3O5 potential for integration into radio frequency devices that demand consistent performance in high-temperature environments.

Thickness-Dependent Structural, Morphological, Optical and Photoluminescence Properties of Spin-coated NiO Thin Films

2025-06-16

Srinivasa Nakkalagadda Venkatakrishna , Basavaraj Angadi , Mahesh Hampapatna Matt | Transactions of the Indian Ceramic Society

Investigating the effects of Hg doping on WO3 nanoflakes: a hydrothermal route to tailored properties

2025-06-15

S. Saranya , L. Balakrishnan , D. Sangeetha +1 more | Digest Journal of Nanomaterials and Biostructures

This study employed hydrothermal technique to synthesize tungsten oxide (WO3) and mercury doped WO3 (Hg:WO3) nanoparticles (NPs). X-ray diffraction results confirmed the monoclinic phase of all NPs. Field emission scanning … This study employed hydrothermal technique to synthesize tungsten oxide (WO3) and mercury doped WO3 (Hg:WO3) nanoparticles (NPs). X-ray diffraction results confirmed the monoclinic phase of all NPs. Field emission scanning electron microscopy verified the nanoflake morphology, while energy dispersive X-ray analysis and X-ray photoelectron spectroscopy confirmed the presence and +2 oxidization state of Hg in doped NPs. Raman spectroscopy provided insights into the chemical structure and phase crystallinity. The optical properties were improved by Hg doping, as evident from ultraviolet-visible diffuse reflectance spectroscopy which showed enhanced visible-light absorption. The bandgap of WO3 reduced from 2.84 to 2.57 eV after Hg doping. The photoluminescence spectroscopy shows decreased emission peak intensity for Hg:WO3. These results indicate that Hg:WO3 NPs are suitable for visible light-driven applications.

Temperature deposition impact on structure and optical properties of NiO: CdO nanostructure thin films

2025-06-15

R. S. Abdul-Sarrar , Raghad S. Mohammed , Lena Hassan +1 more | Journal of Ovonic Research

Nickel and cadmium thin films were spray pyrolysed on glass substrates at temperatures between 200°C and 400°C. The impact of these temperatures on the films' growth mechanism and physical characteristics … Nickel and cadmium thin films were spray pyrolysed on glass substrates at temperatures between 200°C and 400°C. The impact of these temperatures on the films' growth mechanism and physical characteristics was investigated with a view to their potential use in optical applications. Irrespective of the substrate temperature, the films were characterized as having a polycrystalline structure with a cubic orientation predominantly at the (1 1 1) plane. With higher substrate temperatures, there was a notable increase in film transparency. Furthermore, as the substrate temperature increased, the optical band gap decreased between 3.45 eV and 2.48 eV. The results of the study demonstrated the potential for using these films in modern applications such as solar cells.

Synthesis and characterization of aluminum-doped tin oxide nanoparticles for aerospace applications

2025-06-15

Swati Sharma , K S Yamuna , Savita Rani +4 more | Digest Journal of Nanomaterials and Biostructures

Aluminium doped Tin Oxide (ATO) nanoparticles were synthesized using the sol-gel method and analysed for structural, morphological and optical properties. X-ray diffraction (XRD) confirmed the successful incorporation of Al3+ ions … Aluminium doped Tin Oxide (ATO) nanoparticles were synthesized using the sol-gel method and analysed for structural, morphological and optical properties. X-ray diffraction (XRD) confirmed the successful incorporation of Al3+ ions into the SnO2 lattice, retaining its tetragonal rutile structure. The shifts in diffraction peaks to higher 2θ values indicated lattice contraction due to the smaller ionic radius of Al3+ compared to Sn4+. Scanning electron microscopy (SEM) revealed a uniform particle distribution with reduced agglomeration. UV-Visible spectroscopy exhibited a hypsochromic shift in the absorption edge, attributed to bandgap widening caused by aluminium doping. Fourier Transform Infrared (FTIR) spectroscopy identified characteristic vibrational modes of functional groups, confirming chemical bonding. Photoluminescence (PL) studies showed enhanced emission intensities due to oxygen vacancies and electronic interactions between Al dopants and the SnO2 lattice, suggesting defect state creation. The tailored structural and optical properties enhance ATO’s potential in gas sensors utilised in aerospace engines.

Synergistic Enhancement of Near-Infrared Electrochromic Performance in W18O49 Nanowire Thin Films via Copper Doping and Langmuir–Blodgett Assembly

2025-06-14

Yueyang Wu , Honglong Ning , Rongrong Luo +7 more | Inorganics

The development of high-performance electrochromic materials demands innovative approaches to simultaneously control the nanoscale architecture and the electronic structure. We present a dual-modification strategy that synergistically combines copper doping with … The development of high-performance electrochromic materials demands innovative approaches to simultaneously control the nanoscale architecture and the electronic structure. We present a dual-modification strategy that synergistically combines copper doping with the Langmuir–Blodgett (LB) assembly to overcome the traditional performance trade-offs in tungsten oxide-based electrochromic systems. Cu-doped W18O49 nanowires with varying Cu concentrations (0–12 mol%) were synthesized hydrothermally and assembled into thin films via the LB technique, with LB precursors characterized by contact angle, surface tension, viscosity, and thermogravimetric-differential scanning calorimetry (TG-DSC) analyses. The films were systematically evaluated using scanning electron microscopy, X-ray photoelectron spectroscopy, chronoamperometry, and transmittance spectroscopy. Experimental results reveal an optimal Cu-doping concentration of 8 mol%, achieving a near-infrared optical modulation amplitude of 76.24% at 1066 nm, rapid switching kinetics (coloring/bleaching: 5.0/3.0 s), and a coloration efficiency of 133.00 cm2/C. This performance is speculated to be a balance between Cu-induced improvements in ion intercalation kinetics and LB-ordering degradation caused by lattice strain and interfacial charge redistribution, while mitigating excessive doping effects such as structural deterioration and thermodynamic instability. The work establishes a dual-modification framework for designing high-performance electrochromic interfaces, emphasizing the critical role of surface chemistry and nanoscale assembly in advancing adaptive optoelectronic devices like smart windows.

From micro to subnano scale: Insights into the dielectric properties of BiOI nanoplates

2025-06-13

Adrian Radoń , Agnieszka Ciuraszkiewicz , Dariusz Łukowiec +4 more | Materials Today Nano

Synthesis and characterization of V2O5/rGO hybrid nanowire composites as electrode materials for energy storage applications

2025-06-13

Niaz Ahmad Niaz , Abdul Shakoor Khan , Fayyaz Hussain +7 more | Research Square (Research Square)

<title>Abstract</title> Vanadium pentoxide V2O5 a more recent candidate has gained much attention as an electrode material in the field of electrochemical energy storage devices. This work presents V2O5 nanowires (NWs), … <title>Abstract</title> Vanadium pentoxide V2O5 a more recent candidate has gained much attention as an electrode material in the field of electrochemical energy storage devices. This work presents V2O5 nanowires (NWs), synthesized by using a simple and efficient hydrothermal method. The nanowires composite rGO doped V2O5 (V2O5/rGO) was also prepared by hydrothermal method. The DFT-based structural parameters of V₂O₅ and the V₂O₅/rGO composite indicate negative ground state energies, confirming the thermodynamic stability of both systems. Furthermore, the energy–volume (E–V) curve analysis reveals that the V₂O₅/rGO composite attains a lower minimum energy compared to pristine V₂O₅, suggesting enhanced structural stability upon the incorporation of rGO. The structural analysis and morphology of both V2O5 NWs and V2O5/rGO were investigated and compared using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), the electrochemical properties were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and GCD (Galvanostatic Charge-Discharge) techniques. The quasi-rectangular shape-like curves with redox peaks were obtained by the cyclic voltammetry (CV), exhibiting that both the samples V2O5(NWs) and V2O5/rGO have pseudo-capacitive nature. Electrochemical Impedance Spectroscopy (EIS) revealed that there is an enhanced conductivity of V2O5/rGO than pure V2O5 due to the low resistivity of V2O5/rGO nanocomposites. The specific capacitance of V2O5 NWs was found to be 110.3 F/g at 10mv/s scan rate whereas for compositeV2O5/rGO the enhanced specific capacitance was 216.5 F/g at 10 mV/s scan rate. Similarly, results obtained from GCD (galvanostatic charge-discharge) indicate that charge/discharge time, as well as the specific capacitance of composite (V2O5/rGO), is much more enhanced than pure V2O5 NWs electrode. The enhanced characteristics of V2O5/rGO are because of rGO nanosheets as they provide short diffusion distance for ions of electrolyte, high surface area, and large transfer of electrons.

Exploitation of plasma treatment-assisted monocarboxylic cobalt phthalocyanine nanorod growth for high-efficiency photodetection applications

2025-06-13

Ahmed M. El-Mahalawy , M.A. Abd El‐Ghaffar , W. Abbas +1 more | Surfaces and Interfaces

Study on thermophysical properties of Cu-doped PANI nanofluid

2025-06-13

Krishanu Saha , Uttam Kumar Mandal , Monisha Mridha Mandal | Journal of Dispersion Science and Technology

Role of hydrogen dynamics and deposition conditions in photochromic YHO/MoO3 bilayer films

2025-06-13

Edvards Strods , Ma̅rtiņš Zubkins , V. Vibornijs +6 more | Solar Energy Materials and Solar Cells

Large Area Low‐Cost Functional Ceramic Films with High Second Harmonic and Third Harmonic Light Absorption by Two‐Step Fabrication

2025-06-12

Jiaheng Yin , Yaowen Cui , Qiang Gao +6 more | Advanced Engineering Materials

Functional ceramic films with high absorption are of crucial importance for application like eliminating stray light inside the inertial confinement fusion (ICF) devices. A key point for this application is … Functional ceramic films with high absorption are of crucial importance for application like eliminating stray light inside the inertial confinement fusion (ICF) devices. A key point for this application is high absorption rate with low‐cost and relatively easy fabrication process, which largely enables to minimize the effect of stray light of ICF devices. Functional ceramic films (total thickness of 4 μm) are reported in this study with alumina, dielectric plasmonic nanocomposite (Cadmium selenide (CdSe) embedded in alumina (Al 2 O 3 )), and sealing layer (silicon dioxide (SiO 2 )). It can be fabricated by low‐cost two‐step electrochemical machining in huge area ( for demonstration) on many alloy substrates, including curved aluminum alloy 5083 and aluminum alloy 6061 substrates. However, it cannot be fabricated on flexible material substrates. The average absorption rate of functional ceramic films is over 90% in the wavelength range of 300–750 nm. As a results, functional ceramic films are used in the inner frame of ICF devices to eliminate the frequency‐tripled and double‐frequency nanosecond laser stray light with wavelength of 355 and 532 nm, which prevents the optical assembly from secondary damage caused by light remarkably.

A Transparent Semicrystalline Polymer Used in Thermally Responsive Smart Window Application

2025-06-12

Jiacheng Fan , Thomas Wakuta , HyeonJi Hong +7 more | Advanced Functional Materials

Abstract Thermally responsive smart windows based on phase‐changing polymers usually face challenges such as low transmittance at room temperature and limited solar modulation when demanded. A clear poly(SA) or CPSA … Abstract Thermally responsive smart windows based on phase‐changing polymers usually face challenges such as low transmittance at room temperature and limited solar modulation when demanded. A clear poly(SA) or CPSA composed of poly(stearyl acrylate) (poly(SA)) and ethoxylated trimethylolpropane triacrylate is introduced. High optical transparency and high crystallinity at ambient temperature are achieved by ultraviolet curing at a high temperature to suppress the crystallite domain size to the nanometer range. Adding poly(hydroxyethyl methacrylate) (poly(HEMA)) in the formula produces a micrometer‐size phase‐separated terpolymer system where the CPSA phase retains its crystallinity. The refractive index of the poly(HEMA) phase is tuned to match that of the CPSA phase, and the terpolymer film is transparent at 20 °C with visible transmittance up to 91.4%. Above the transition temperature of 42 to 46 °C, CPSA crystal melting leads to light scattering at the phase boundaries, creating an opaque appearance. The transmittance modulation is 81.4%, 87.7%, and 76.5% for solar (300–2500 nm), visible (380–780 nm), and near‐infrared (780–2500 nm) spectrum, respectively. Furthermore, a styrofoam chamber covered with the terpolymer smart window can effectively reduce the chamber interior temperature increase by 8.5 °C compared to the reference glass window.

Hybrid Plasmonic Nanorods/VO2 Photodetectors Sensitive to Short‐Wave Infrared Photons with Fast Response

2025-06-12

Zhuoqun Fang , A. Zimmers , Ke Li +6 more | Advanced Electronic Materials

Abstract Thermal detectors, such as bolometers functioning by detecting the radiation‐induced temperature changes, represent a promising route to achieve infrared detection and imaging. In this context, vanadium dioxide (VO 2 … Abstract Thermal detectors, such as bolometers functioning by detecting the radiation‐induced temperature changes, represent a promising route to achieve infrared detection and imaging. In this context, vanadium dioxide (VO 2 ), a narrow bandgap ( E g ) semiconductor ( E g ≈0.6–0.7 eV) with a unique near‐room‐temperature reversible metal‐to‐insulator transition (MIT), has emerged as one of the key materials for uncooled bolometer‐type short‐wave infrared (SWIR) photodetectors. In this work, photodetectors sensitive to the SWIR spectrum are fabricated to function at room‐temperature by coupling solution‐processed tungsten (W 6+ )‐doped VO 2 thin films to colloidal plasmonic gold (Au) nanorods (NRs). Due to the dual beneficial roles of the NRs as both the photothermal heating and plasmonic antenna effects, the hybrid Au NR/VO 2 devices exhibit significant advantages in terms of photosensitivity and detection range in comparison to the control devices without plasmonics. Together with the low external DC bias required (0.5 V) and the fast response speed ( t rise down to 14 ms), the present hybrid plasmonic‐VO 2 thin film devices suggest a viable approach toward the development of future cost‐effective SWIR photodetectors.

Charge Transport and Noise Characteristics in WO3 Hybrid Nanowire–Nanoparticle Networks: Insights into Conduction Mechanisms and Trap Dynamics

2025-06-11

Charu Singh , Nirat Ray | The Journal of Physical Chemistry C