Materials Science › Materials Chemistry

Luminescence Properties of Advanced Materials

Works Count: 95538

Wikipedia

Description

This cluster of papers covers a wide range of research on upconversion nanoparticles, including their synthesis, applications in biological imaging and theranostics, enhancement of solar cell efficiency, temperature sensing capabilities, utilization of rare earth ions, and their role in photon upconversion for solid-state lighting.

Keywords

Upconversion Nanoparticles; Luminescent Materials; Nanocrystal Synthesis; Biological Imaging; Theranostics; Solar Cell Efficiency; Temperature Sensing; Rare Earth Ions; Photon Upconversion; Solid-State Lighting

Theory of Concentration Quenching in Inorganic Phosphors

1954-06-01

D. L. Dexter , James H. Schulman

A theory is presented for concentration quenching in solid systems, based on the migration of excitation energy from one activator center to another and eventually to an imperfection which may … A theory is presented for concentration quenching in solid systems, based on the migration of excitation energy from one activator center to another and eventually to an imperfection which may act as an energy sink. Calculations are made on the dependence of the fluorescence yield on concentration, and to indicate typical activator concentrations at which appreciable quenching may be expected to occur. If the transition in the activator is of the electric dipole or electric quadrupole type, appreciable quenching may arise when the activator concentration is 10-3 to 10-2; if it is a magnetic dipole transition, transfer will occur by exchange, rather than by overlapping of magnetic dipole fields, and the critical concentration will be of the order of a few percent. The implications of transfer phenomena upon the observed absence of luminescence in most ``pure'' inorganic crystals are discussed, and it is concluded that transfer rates are so high in strongly absorbing crystals that the energy can easily migrate to a very few sinks dispersed throughout the lattice.

A New Long Phosphorescent Phosphor with High Brightness, SrAl2 O 4 : Eu2 + , Dy3 +

1996-08-01

T. Matsuzawa , Yohta Aoki , Nobuyuki Takeuchi +1 more

A green emitting phosphor with very bright and long lasting phosphorescence has been newly developed. The incorporation of ion into the system as an auxiliary activator dominates the phosphorescence, thermoluminescence, … A green emitting phosphor with very bright and long lasting phosphorescence has been newly developed. The incorporation of ion into the system as an auxiliary activator dominates the phosphorescence, thermoluminescence, and photoconductivity characteristics of the phosphor to a large extent. Evidence is presented for the mechanism that the phosphorescence is ascribed to the photoconductivity due to holes, and to the trapping and thermal release of the holes by ions in the system. The incorporation of the ion forms a highly dense trapping level located at a suitable depth in relation to the thermal release rate at room temperature, thus producing the very bright and long phosphorescence.

Inorganic Luminescent Materials: 100 Years of Research and Application

2003-07-01

Claus Feldmann , Thomas Jüstel , Cees Ronda +1 more

Abstract Up until approximately 80 years ago, only black‐body radiation (including natural sources) was available to illuminate our environment. To realise state‐of‐the‐art lamps, TV sets, monitors, and medical scanners, took … Abstract Up until approximately 80 years ago, only black‐body radiation (including natural sources) was available to illuminate our environment. To realise state‐of‐the‐art lamps, TV sets, monitors, and medical scanners, took an enormous scientific and technical effort. Inorganic luminescent materials are key components, which were, are, and will be prerequisite to the functionality and success of many lighting and display systems. In this Highlight, a hundred years of inorganic luminescent material research are reviewed.

Highly efficient non-rare-earth red emitting phosphor for warm white light-emitting diodes

2014-07-08

Haomiao Zhu , Chun Che Lin , Wenqin Luo +7 more

View PDF Chat

Recent Developments in the Field of Inorganic Phosphors

2009-04-06

Henning A. Höppe

Because fossil fuels are becoming scarce and because of the expected climate change, our standard of living can only be maintained by a significant increase in energy efficiency. Large amounts … Because fossil fuels are becoming scarce and because of the expected climate change, our standard of living can only be maintained by a significant increase in energy efficiency. Large amounts of energy are consumed for lighting and during operation of displays. Thus, the targets are the development of economical light sources like white-light-emitting diodes and display panels with enhanced efficiency. Solar energy is converted into electricity by solar cells, and their efficiency must be improved considerably. A possible contribution might be delivered by phosphors which allow the conversion of thermal radiation into electrical energy. Although the target of energy efficiency is very important, we must not overlook that medical imaging diagnostic methods require efficient and sensitive detectors. For the solution of these central questions, inorganic solid-state materials doped with rare-earth ions are very promising and are therefore in the focus of current research activities.

The superposition model of crystal fields

1989-06-01

D J Newman , Benjamin Ng

The superposition model was originally developed to separate the geometrical and physical information in crystal field parameters. Its success in the analysis of lanthanide spectra has been paralleled by the … The superposition model was originally developed to separate the geometrical and physical information in crystal field parameters. Its success in the analysis of lanthanide spectra has been paralleled by the success of the related angular overlap model in the analysis of d-electron spectra. The basic ideas, method of application and reliability of the superposition model are discussed and its relationship with the angular overlap model is clarified. Developments described are the application of the superposition model to the ground (L=0) multiplet splittings of d5 and f7 ions, orbit-lattice interactions, transition intensities and correlation crystal fields. Special attention is paid to work which has been claimed to support or disprove the postulates of the model.

Spectral Intensities of the Trivalent Lanthanides and Actinides in Solution. II. Pm3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, and Ho3+

1968-11-15

W. T. Carnall , P. R. Fields , K. Rajnak

We have correlated the experimentally determined band intensities in the solution absorption spectra of the trivalent lanthanides with a theoretical expression derived by Judd. The spectra were measured in a … We have correlated the experimentally determined band intensities in the solution absorption spectra of the trivalent lanthanides with a theoretical expression derived by Judd. The spectra were measured in a single medium, dilute acid solution, and, in most cases, in the range ≈6000–50 000 cm−1. In general, the correlation between calculated and observed intensities was very good, even at higher energies. The variation of the intensity parameters over the series is discussed as is the somewhat unexpected degree of correlation obtained in the ultraviolet region.

Power dependence of upconversion luminescence in lanthanide and transition-metal-ion systems

2000-02-01

Markus Pollnau , Daniel R. Gamelin , Stefan R. Lüthi +2 more

We show theoretically with the simplest possible model that the intensity of an upconversion luminescence that is excited by the sequential absorption of n photons has a dependence on absorbed … We show theoretically with the simplest possible model that the intensity of an upconversion luminescence that is excited by the sequential absorption of n photons has a dependence on absorbed pump power P, which may range from the limit of ${P}^{n}$ down to the limit of ${P}^{1}$ for the upper state and less than ${P}^{1}$ for the intermediate states. The two limits are identified as the cases of infinitely small and infinitely large upconversion rates, respectively. In the latter case, the dependence of luminescence intensities from intermediate excited states on pump power changes with the underlying upconversion and decay mechanisms. In certain situations, energy-transfer upconversion and excited-state absorption can be distinguished by the measured slopes. The competition between linear decay and upconversion in the individual excitation steps of sequential upconversion can be analyzed. The influence of nonuniform distributions of absorbed pump power or of a subset of ions participating in energy-transfer upconversion is investigated. These results are of importance for the interpretation of excitation mechanisms of luminescent and laser materials. We verify our theoretical results by experimental examples of multiphoton-excited luminescence in ${\mathrm{Cs}}_{3}{\mathrm{Lu}}_{2}{\mathrm{Cl}}_{9}{:\mathrm{E}\mathrm{r}}^{3+},$ ${\mathrm{Ba}}_{2}{\mathrm{YCl}}_{7}{:\mathrm{E}\mathrm{r}}^{3+},$ ${\mathrm{LiYF}}_{4}{:\mathrm{N}\mathrm{d}}^{3+},$ and ${\mathrm{Cs}}_{2}{\mathrm{ZrCl}}_{6}{:\mathrm{R}\mathrm{e}}^{4+}.$

View PDF Chat

Energy transfer in oxidic phosphors

1968-12-01

G. Blasse

Correlation between photoluminescence and oxygen vacancies in ZnO phosphors

1996-01-15

K. Vanheusden , C. H. Seager , W. L. Warren +2 more

By combining electron paramagnetic resonance (EPR), optical absorption, and photoluminescence (PL) spectroscopy, a strong correlation is observed between the green 510 nm emission, the free-carrier concentration, and the density of … By combining electron paramagnetic resonance (EPR), optical absorption, and photoluminescence (PL) spectroscopy, a strong correlation is observed between the green 510 nm emission, the free-carrier concentration, and the density of singly ionized oxygen vacancies in commercial ZnO phosphor powders. From these results, we demonstrate that free-carrier depletion at the particle surface, and its effect on the ionization state of the oxygen vacancy, can strongly impact the green emission intensity. The relevance of these observations with respect to low-voltage field emission displays is discussed.

Thermoluminescence of solids

1985-12-01

S. W. S. McKeever

Simultaneous phase and size control of upconversion nanocrystals through lanthanide doping

2010-02-01

Feng Wang , Yu Han , Chin Seong Lim +7 more

Energy transfer between inequivalent Eu2+ ions

1986-04-01

G. Blasse

Temperature Sensing Using Fluorescent Nanothermometers

2010-05-04

Fiorenzo Vetrone , Rafik Naccache , Alicia Zamarrón +7 more

Acquiring the temperature of a single living cell is not a trivial task. In this paper, we devise a novel nanothermometer, capable of accurately determining the temperature of solutions as … Acquiring the temperature of a single living cell is not a trivial task. In this paper, we devise a novel nanothermometer, capable of accurately determining the temperature of solutions as well as biological systems such as HeLa cancer cells. The nanothermometer is based on the temperature-sensitive fluorescence of NaYF(4):Er(3+),Yb(3+) nanoparticles, where the intensity ratio of the green fluorescence bands of the Er(3+) dopant ions ((2)H(11/2) --> (4)I(15/2) and (4)S(3/2) --> (4)I(15/2)) changes with temperature. The nanothermometers were first used to obtain thermal profiles created when heating a colloidal solution of NaYF(4):Er(3+),Yb(3+) nanoparticles in water using a pump-probe experiment. Following incubation of the nanoparticles with HeLa cervical cancer cells and their subsequent uptake, the fluorescent nanothermometers measured the internal temperature of the living cell from 25 degrees C to its thermally induced death at 45 degrees C.

A Theory of Sensitized Luminescence in Solids

1953-05-01

D. L. Dexter

The term ``sensitized luminescence'' in crystalline phosphors refers to the phenomenon whereby an impurity (activator, or emitter) is enabled to luminesce upon the absorption of light in a different type … The term ``sensitized luminescence'' in crystalline phosphors refers to the phenomenon whereby an impurity (activator, or emitter) is enabled to luminesce upon the absorption of light in a different type of center (sensitizer, or absorber) and upon the subsequent radiationless transfer of energy from the sensitizer to the activator. The resonance theory of Förster, which involves only allowed transitions, is extended to include transfer by means of forbidden transitions which, it is concluded, are responsible for the transfer in all inorganic systems yet investigated. The transfer mechanisms of importance are, in order of decreasing strength, the overlapping of the electric dipole fields of the sensitizer and the activator, the overlapping of the dipole field of the sensitizer with the quadrupole field of the activator, and exchange effects. These mechanisms will give rise to ``sensitization'' of about 103−104, 102, and 30 lattice sites surrounding each sensitizer in typical systems. The dependence of transfer efficiency upon sensitizer and activator concentrations and on temperature are discussed. Application is made of the theory to experimental results on inorganic phosphors, and further experiments are suggested.

Upconversion and Anti-Stokes Processes with f and d Ions in Solids

2003-11-18

F. Auzel

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUpconversion and Anti-Stokes Processes with f and d Ions in SolidsFrançois AuzelView Author Information GOTR, UMR 7574-CNRS, 1, Place A-Briand, 92195 Meudon Cedex, France Cite this: Chem. … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUpconversion and Anti-Stokes Processes with f and d Ions in SolidsFrançois AuzelView Author Information GOTR, UMR 7574-CNRS, 1, Place A-Briand, 92195 Meudon Cedex, France Cite this: Chem. Rev. 2004, 104, 1, 139–174Publication Date (Web):November 18, 2003Publication History Received25 February 2003Published online18 November 2003Published inissue 1 January 2004https://pubs.acs.org/doi/10.1021/cr020357ghttps://doi.org/10.1021/cr020357gresearch-articleACS PublicationsCopyright © 2004 American Chemical SocietyRequest reuse permissionsArticle Views32334Altmetric-Citations4309LEARN 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:Energy,Energy transfer,Ions,Lasers,Luminescence Get e-Alerts

Phosphors in phosphor-converted white light-emitting diodes: Recent advances in materials, techniques and properties

2010-08-10

Shi Ye , Fen Xiao , Yu Pan +2 more

Narrow-band red-emitting Sr[LiAl3N4]:Eu2+ as a next-generation LED-phosphor material

2014-06-20

Philipp Pust , Volker Weiler , Cora Hecht +7 more

The Electron Trap Mechanism of Luminescence in Sulphide and Silicate Phosphors

1948-06-01

G. F. J. Garlick , A F Gibson

Phosphorescence and thermoluminescence emission from photoconducting impurity activated phosphors have been satisfactorily explained by the storage of electrons, freed from luminescence centres or other atoms of the solid, in metastable … Phosphorescence and thermoluminescence emission from photoconducting impurity activated phosphors have been satisfactorily explained by the storage of electrons, freed from luminescence centres or other atoms of the solid, in metastable energy levels known as electron traps. Electrons escaping from these traps give rise to emission when they recombine with luminescence centres but there is a probability that they may be retrapped in empty electron traps before their final recombination with centres. The present theoretical and experimental studies attempt to determine the extent to which retrapping does occur and what effects it will have in modifying the phosphorescence and thermoluminescence characteristics. Theoretical treatment shows that there are marked differences in these characteristics for conditions when the retrapping process is present and for those when it is negligible. Experimental investigations of the characteristics of specimens of zinc sulphide, zinc silicate and strontium silicate phosphors indicate that, except under special conditions, retrapping of electrons is negligible. These results together with other work can be explained theoretically if it is assumed that electron traps operative in the luminescence process are spatially associated with the immediate neighbourhood of the luminescence centres formed by activating impurities. This new concept is also supported by the relations found between the luminescence characteristics and the dielectric changes in phosphors of the zinc sulphide type.

Sunlight-activated long-persistent luminescence in the near-infrared from Cr3+-doped zinc gallogermanates

2011-11-20

Zhengwei Pan , Yi-Ying Lu , Feng Liu

Electronic Energy Levels in the Trivalent Lanthanide Aquo Ions. I. Pr3+, Nd3+, Pm3+, Sm3+, Dy3+, Ho3+, Er3+, and Tm3+

1968-11-15

W. T. Carnall , P. R. Fields , K. Rajnak

The free-ion energy-level schemes of the Pr3+, Nd3+, Pm3+, Sm3+, Dy3+, Ho3+, Er3+, and Tm3+ aquo ions have been determined from their absorption spectra in dilute acid solution at 25°. … The free-ion energy-level schemes of the Pr3+, Nd3+, Pm3+, Sm3+, Dy3+, Ho3+, Er3+, and Tm3+ aquo ions have been determined from their absorption spectra in dilute acid solution at 25°. Energy-level assignments were made by comparison with crystal spectra, and on the basis of correlations between calculated and observed band intensities. For most of the ions, it was possible to identify several transitions giving rise to bands at energies as high as 45 000–50 000 cm−1. Sufficient numbers of assignments were made to justify inclusion of the effects of configuration interaction in the calculation of the energy-level parameters. Variation of the electrostatic, spin–orbit coupling, and configuration-interaction parameters across the lanthanide series is examined.

Upconversion nanoparticles in biological labeling, imaging, and therapy

2010-01-01

Feng Wang , Debapriya Banerjee , Yongsheng Liu +2 more

Upconversion refers to non-linear optical processes that convert two or more low-energy pump photons to a higher-energy output photon. After being recognized in the mid-1960s, upconversion has attracted significant research … Upconversion refers to non-linear optical processes that convert two or more low-energy pump photons to a higher-energy output photon. After being recognized in the mid-1960s, upconversion has attracted significant research interest for its applications in optical devices such as infrared quantum counter detectors and compact solid-state lasers. Over the past decade, upconversion has become more prominent in biological sciences as the preparation of high-quality lanthanide-doped nanoparticles has become increasingly routine. Owing to their small physical dimensions and biocompatibility, upconversion nanoparticles can be easily coupled to proteins or other biological macromolecular systems and used in a variety of assay formats ranging from bio-detection to cancer therapy. In addition, intense visible emission from these nanoparticles under near-infrared excitation, which is less harmful to biological samples and has greater sample penetration depths than conventional ultraviolet excitation, enhances their prospects as luminescent stains in bio-imaging. In this article, we review recent developments in optical biolabeling and bio-imaging involving upconversion nanoparticles, simultaneously bringing to the forefront the desirable characteristics, strengths and weaknesses of these luminescent nanomaterials.

Upconversion Nanoparticles: Design, Nanochemistry, and Applications in Theranostics

2014-03-10

Guanying Chen , Hailong Qiu , Paras N. Prasad +1 more

ADVERTISEMENT RETURN TO ISSUEReviewNEXTUpconversion Nanoparticles: Design, Nanochemistry, and Applications in TheranosticsGuanying Chen*†‡, Hailong Qiu†‡, Paras N. Prasad*‡§, and Xiaoyuan Chen*∥View Author Information† School of Chemical Engineering and Technology, Harbin Institute … ADVERTISEMENT RETURN TO ISSUEReviewNEXTUpconversion Nanoparticles: Design, Nanochemistry, and Applications in TheranosticsGuanying Chen*†‡, Hailong Qiu†‡, Paras N. Prasad*‡§, and Xiaoyuan Chen*∥View Author Information† School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin, Heilongjiang 150001, China‡ Department of Chemistry and the Institute for Lasers, Photonics, and Biophotonics, University at Buffalo, State University of New York, Buffalo, New York 14260, United States§ Department of Chemistry, Korea University, Seoul 136-701, Korea∥ Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland 20892-2281, United States*E-mail: [email protected]*E-mail: [email protected]*E-mail: [email protected]Cite this: Chem. Rev. 2014, 114, 10, 5161–5214Publication Date (Web):March 10, 2014Publication History Received5 August 2013Published online10 March 2014Published inissue 28 May 2014https://doi.org/10.1021/cr400425hCopyright © 2014 American Chemical SocietyRIGHTS & PERMISSIONSACS AuthorChoiceArticle Views75082Altmetric-Citations1907LEARN 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 (60 MB) Get e-AlertsSUBJECTS:Biological imaging,Ions,Lanthanides,Luminescence,Nanoparticles Get e-Alerts

View PDF Chat

Highly Efficient Multicolour Upconversion Emission in Transparent Colloids of Lanthanide‐Doped NaYF4 Nanocrystals

2004-12-16

Stephan Heer , Karsten Kömpe , H. U. Güdel +1 more

Highly efficient photon upconversion in solution is demonstrated for the first time. Transparent colloidal solutions of Yb/Er and Yb/Tm doped NaYF4 nanocrystals show bright upconversion emission in the red, green, … Highly efficient photon upconversion in solution is demonstrated for the first time. Transparent colloidal solutions of Yb/Er and Yb/Tm doped NaYF4 nanocrystals show bright upconversion emission in the red, green, and blue spectral region by excitation around 1 μm with a laser of moderate power (see Figure). These new systems show a substantial improvement on the order of 108 compared to previously reported systems. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2089/2004/c0772_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.

Hexagonal Sodium Yttrium Fluoride Based Green and Blue Emitting Upconversion Phosphors

2004-03-02

Karl W. Krämer , Daniel Biner , G. Frei +3 more

Hexagonal sodium yttrium fluoride, NaYF4, is the most efficient host material to date for green (Yb3+/Er3+ doped) and blue (Yb3+/Tm3+ doped) upconversion (UC) phosphors, i.e., phosphors which emit visible light … Hexagonal sodium yttrium fluoride, NaYF4, is the most efficient host material to date for green (Yb3+/Er3+ doped) and blue (Yb3+/Tm3+ doped) upconversion (UC) phosphors, i.e., phosphors which emit visible light upon infrared (IR) excitation. The structure of the hexagonal phase gives rise to controversy about the cation sites and distribution. The X-ray diffraction patterns of our phosphors do not fit well with the crystal structure reported for NaNdF4 (space group P6̄, Z = 1.5). The Na:M ratio (M = Y, Nd, Er, Tm, Yb) of the hexagonal phase deviates significantly from 1:1, and it depends on M and the preparation temperature. It is proposed that the hexagonal phase is isostructural to the chlorides Na3xM2-xCl6 with M = La−Sm. This structure (space group P63/m, Z = 1) contains only one M3+ site which is partially occupied by Na+, and the formula Na3xM2-xF6 (x ≈ 0.45) accounts for the nonstoichiometry. The model was derived from powder X-ray diffraction on the green and blue phosphor materials as well as the pure Nd, Y, and Yb compounds. The light emission properties of the material crucially depend on the phase purity, doping ratio, Na:M ratio, and preparation temperature. Because earlier spectroscopic investigations generally suffered from impure materials which reduced the UC efficiency, a new, reproducible preparation route was developed. Its key features are an excess of NaF in the synthesis, i.e., a 2:1 ratio of Na:M, the use of HF gas for fluorination, and a process temperature lower than the melting point of the respective NaF/MF3 eutecticum. It yields the pure hexagonal phase without admixture of the cubic phase or other impurities except for minor inclusions of NaF. Upon IR excitation at 10 245 cm-1, the samples doped with 18% Yb + 2% Er and 25% Yb + 0.3% Tm showed the highest UC efficiencies for green and blue emission, respectively. Relative UC efficiencies were measured with a powder test setup in a standard procedure. The doping ratios and all steps of the synthesis were optimized with respect to the UC efficiency. The obtained phosphor materials show no degradation under high-power IR laser excitation.

Visible Quantum Cutting in LiGdF 4 :Eu 3+ Through Downconversion

1999-01-29

R. T. Wegh , H. Donker , K.D Oskam +1 more

For mercury-free fluorescent lamps and plasma display panels, alternative luminescent materials are required for the efficient conversion of vacuum ultraviolet radiation to visible light. Quantum cutting involving the emission of … For mercury-free fluorescent lamps and plasma display panels, alternative luminescent materials are required for the efficient conversion of vacuum ultraviolet radiation to visible light. Quantum cutting involving the emission of two visible photons for each vacuum ultraviolet photon absorbed is demonstrated in Eu3+-doped LiGdF4 with the concept of downconversion. Upon excitation of Gd3+ with a high-energy photon, two visible photons can be emitted by Eu3+ through an efficient two-step energy transfer from Gd3+ to Eu3+, with a quantum efficiency that approaches 200 percent.

Upconversion Multicolor Fine-Tuning: Visible to Near-Infrared Emission from Lanthanide-Doped NaYF4 Nanoparticles

2008-04-01

Feng Wang , Xiaogang Liu

A general approach to fine-tuning the upconversion emission colors, based upon a single host source of NaYF4 nanoparticles doped with Yb3+, Tm3+, and Er3+, is presented. The emission intensity balance … A general approach to fine-tuning the upconversion emission colors, based upon a single host source of NaYF4 nanoparticles doped with Yb3+, Tm3+, and Er3+, is presented. The emission intensity balance can be precisely controlled using different host−activator systems and dopant concentrations. The approach allows access to a wide range of luminescence emission from visible to near-infrared by single-wavelength excitation.

Recent advances in the chemistry of lanthanide-doped upconversion nanocrystals

2009-01-01

Feng Wang , Xiaogang Liu

Lanthanide ions exhibit unique luminescent properties, including the ability to convert near infrared long-wavelength excitation radiation into shorter visible wavelengths through a process known as photon upconversion. In recent years … Lanthanide ions exhibit unique luminescent properties, including the ability to convert near infrared long-wavelength excitation radiation into shorter visible wavelengths through a process known as photon upconversion. In recent years lanthanide-doped upconversion nanocrystals have been developed as a new class of luminescent optical labels that have become promising alternatives to organic fluorophores and quantum dots for applications in biological assays and medical imaging. These techniques offer low autofluorescence background, large anti-Stokes shifts, sharp emission bandwidths, high resistance to photobleaching, and high penetration depth and temporal resolution. Such techniques also show potential for improving the selectivity and sensitivity of conventional methods. They also pave the way for high throughput screening and miniaturization. This tutorial review focuses on the recent development of various synthetic approaches and possibilities for chemical tuning of upconversion properties, as well as giving an overview of biological applications of these luminescent nanocrystals.

Upconversion nanophosphors for small-animal imaging

2011-10-19

Jing Zhou , Zhuang Liu , Fuyou Li

Rare-earth upconversion nanophosphors (UCNPs), when excited by continuous-wave near-infrared light, exhibit a unique narrow photoluminescence with higher energy. Such special upconversion luminescence makes UCNPs promising as bioimaging probes with attractive … Rare-earth upconversion nanophosphors (UCNPs), when excited by continuous-wave near-infrared light, exhibit a unique narrow photoluminescence with higher energy. Such special upconversion luminescence makes UCNPs promising as bioimaging probes with attractive features, such as no auto-fluorescence from biological samples and a large penetration depth. As a result, UCNPs have emerged as novel imaging agents for small animals. In this critical review, recent reports regarding the synthesis of water-soluble UCNPs and their surface modification and bioconjugation chemistry are summarized. The applications of UCNPs for small-animal imaging, including tumor-targeted imaging, lymphatic imaging, vascular imaging and cell tracking are reviewed in detail. The exploration of UCNPs as multifunctional nanoscale carriers for integrated imaging and therapy is also presented. The biodistribution and toxicology of UCNPs are further described. Finally, we discuss the challenges and opportunities in the development of UCNP-based nanoplatforms for small-animal imaging (276 references).

Thermometry at the nanoscale

2012-01-01

Carlos D. S. Brites , Patrícia P. Lima , Nuno J. O. Silva +4 more

Non-invasive precise thermometers working at the nanoscale with high spatial resolution, where the conventional methods are ineffective, have emerged over the last couple of years as a very active field … Non-invasive precise thermometers working at the nanoscale with high spatial resolution, where the conventional methods are ineffective, have emerged over the last couple of years as a very active field of research. This has been strongly stimulated by the numerous challenging requests arising from nanotechnology and biomedicine. This critical review offers a general overview of recent examples of luminescent and non-luminescent thermometers working at nanometric scale. Luminescent thermometers encompass organic dyes, QDs and Ln3+ions as thermal probes, as well as more complex thermometric systems formed by polymer and organic–inorganic hybrid matrices encapsulating these emitting centres. Non-luminescent thermometers comprise of scanning thermal microscopy, nanolithography thermometry, carbon nanotube thermometry and biomaterials thermometry. Emphasis has been put on ratiometric examples reporting spatial resolution lower than 1 micron, as, for instance, intracellular thermometers based on organic dyes, thermoresponsive polymers, mesoporous silica NPs, QDs, and Ln3+-based up-converting NPs and β-diketonate complexes. Finally, we discuss the challenges and opportunities in the development for highly sensitive ratiometric thermometers operating at the physiological temperature range with submicron spatial resolution.

View PDF Chat

Tuning upconversion through energy migration in core–shell nanoparticles

2011-10-23

Feng Wang , Renren Deng , Juan Wang +5 more

A systematic analysis of the spectra of the lanthanides doped into single crystal LaF3

1989-04-01

W. T. Carnall , G. L. Goodman , K. Rajnak +1 more

The optical spectra of the lanthanides doped into single crystal LaF3 have been interpreted in terms of transitions within 4f N configurations. Energy matrices combining free-ion terms with a crystal … The optical spectra of the lanthanides doped into single crystal LaF3 have been interpreted in terms of transitions within 4f N configurations. Energy matrices combining free-ion terms with a crystal field for an approximate model which assumes C2v instead of the actual C2 site symmetry were diagonalized. Excellent correlations were obtained between experimental transition energies and the computed level structures. We also report the results of previously unpublished experimental spectroscopic investigations of Nd3+ and Sm3+:LaF3, as well as predicted energy levels for Pm3+:LaF3. The spectroscopic data for each ion were independently interpreted using an effective-operator model, then the model parameters were intercompared. Systematic trends have been identified, and a comprehensive energy level diagram is presented.

How to produce white light in a single-phase host?

2013-12-17

Mengmeng Shang , Chunxia Li , Jun Lin

White light-emitting diodes (WLEDs) as new solid-state light sources have a greatly promising application in the field of lighting and display. So far much effort has been devoted to exploring … White light-emitting diodes (WLEDs) as new solid-state light sources have a greatly promising application in the field of lighting and display. So far much effort has been devoted to exploring novel luminescent materials for WLEDs. Currently the major challenges in WLEDs are to achieve high luminous efficacy, high chromatic stability, brilliant color-rending properties, and price competitiveness against fluorescent lamps, which rely critically on the phosphor properties. In recent years, numerous efforts have been made to develop single-phase white-light-emitting phosphors for near-ultraviolet or ultraviolet excitation to solve the above challenges with certain achievements. This review article highlights the current methods to realize the white light emission in a single-phase host, including: (1) doping a single rare earth ion (Eu(3+), Eu(2+) or Dy(3+)) into appropriate single-phase hosts; (2) co-doping various luminescent ions with different emissions into a single matrix simultaneously, such as Tm(3+)/Tb(3+)/Eu(3+), Tm(3+)/Dy(3+), Yb(3+)/Er(3+)/Tm(3+)etc.; (3) codoping different ions in one host to control emission color via energy transfer processes; and (4) controlling the concentration of the defect and reaction conditions of defect-related luminescent materials.

Temperature Quenching of Yellow Ce3+ Luminescence in YAG:Ce

2009-05-04

V. Bachmann , Cees Ronda , Andries Meijerink

Yttrium aluminum garnet (YAG) doped with Ce3+ is the phosphor of choice for the conversion of blue to yellow light in the rapidly expanding market of white light LEDs, but … Yttrium aluminum garnet (YAG) doped with Ce3+ is the phosphor of choice for the conversion of blue to yellow light in the rapidly expanding market of white light LEDs, but it is generally thought to suffer from a low luminescence quenching temperature. The luminescence quenching temperature is an important parameter, especially in high-power LEDs, but surprisingly no systematic research has been done to measure and understand the temperature quenching of the yellow Ce luminescence in YAG:Ce. Here we report on the luminescence temperature quenching in YAG:Ce. For a wide range of Ce concentrations (between 0.033% and 3.3%) the temperature dependence of the emission intensity and the luminescence lifetimes are reported. The intrinsic quenching temperature of the Ce luminescence is shown to be very high (>700 K). The lower quenching temperatures reported in the literature are explained by thermally activated concentration quenching (for highly doped systems) and the temperature dependence of the oscillator strength (for low doping concentrations). In addition, high-resolution spectra are reported, which provide insight into the position of the zero-phonon transition (20450 cm−1), the Stokes shift (2400 cm−1), the energy of the dominant phonon mode (200 cm−1), and the Huang−Rhys parameter (S = 6). These parameters are compared with ab initio calculations on the position of and relaxation in the excited 5d state of Ce3+ in YAG, which can aid in providing a better theoretical understanding of the temperature quenching.

Characterization of Energy Transfer Interactions between Rare Earth Ions

1967-01-01

L. G. Van Uitert

Energy transfer studies employing the sodium rare earth tungstates (scheelite structure) indicate a number of modes of, and requirements for, nonradiative interaction. Direct dipole‐dipole interactions are prevalent. However, dipole‐quadrupole interactions … Energy transfer studies employing the sodium rare earth tungstates (scheelite structure) indicate a number of modes of, and requirements for, nonradiative interaction. Direct dipole‐dipole interactions are prevalent. However, dipole‐quadrupole interactions are observed for the states of the larger rare earth ions that lie high in energy. The relation of lifetime to intensity changes with the mode of transfer. Phonon assisted transfer is enhanced by exchange coupling between rare earth ions in nearest or next nearest neighbor positions. Excitation may migrate between Tb ions in such positions when thermally activated and provided a suitable quenching center (e.g., Nd, Eu) is present. Such migration appears to be directional in comparison to transfer by radiation reabsorption. The latter is essentially random. Methods for analyzing lifetime data for transfer interactions are also discussed.

The Spectra of the Doubly and Triply Ionized Rare Earths

1963-07-01

G. H. Dieke , H. M. Crosswhite

The present status of our knowledge of the structure of the spectra of the doubly and triply ionized spectra of the rare earths is derived partly from experimental data of … The present status of our knowledge of the structure of the spectra of the doubly and triply ionized spectra of the rare earths is derived partly from experimental data of the emission spectra of the free ions which provide the energy level scheme in great detail but are difficult and laborious to analyze. For the lower levels knowledge of the structure comes from the crystal absorption and fluoresence spectra. In all cases approximate theoretical calculations of the energies are essential.

Enhancing solar cell efficiency: the search for luminescent materials as spectral converters

2012-10-16

Xiaoyong Huang , Sanyang Han , Wei Huang +1 more

Photovoltaic (PV) technologies for solar energy conversion represent promising routes to green and renewable energy generation. Despite relevant PV technologies being available for more than half a century, the production … Photovoltaic (PV) technologies for solar energy conversion represent promising routes to green and renewable energy generation. Despite relevant PV technologies being available for more than half a century, the production of solar energy remains costly, largely owing to low power conversion efficiencies of solar cells. The main difficulty in improving the efficiency of PV energy conversion lies in the spectral mismatch between the energy distribution of photons in the incident solar spectrum and the bandgap of a semiconductor material. In recent years, luminescent materials, which are capable of converting a broad spectrum of light into photons of a particular wavelength, have been synthesized and used to minimize the losses in the solar-cell-based energy conversion process. In this review, we will survey recent progress in the development of spectral converters, with a particular emphasis on lanthanide-based upconversion, quantum-cutting and down-shifting materials, for PV applications. In addition, we will also present technical challenges that arise in developing cost-effective high-performance solar cells based on these luminescent materials.

Controlling upconversion nanocrystals for emerging applications

2015-11-01

Bo Zhou , Bingyang Shi , Dayong Jin +1 more

Effects of crystallization and dopant concentration on the emission behavior of TiO2:Eu nanophosphors

2012-01-03

Mou Pal , Umapada Pal , Justo Miguel Gracia Jiménez +1 more

Uniform, spherical-shaped TiO2:Eu nanoparticles with different doping concentrations have been synthesized through controlled hydrolysis of titanium tetrabutoxide under appropriate pH and temperature in the presence of EuCl3·6H2O. Through air annealing … Uniform, spherical-shaped TiO2:Eu nanoparticles with different doping concentrations have been synthesized through controlled hydrolysis of titanium tetrabutoxide under appropriate pH and temperature in the presence of EuCl3·6H2O. Through air annealing at 500°C for 2 h, the amorphous, as-grown nanoparticles could be converted to a pure anatase phase. The morphology, structural, and optical properties of the annealed nanostructures were studied using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy [EDS], and UV-Visible diffuse reflectance spectroscopy techniques. Optoelectronic behaviors of the nanostructures were studied using micro-Raman and photoluminescence [PL] spectroscopies at room temperature. EDS results confirmed a systematic increase of Eu content in the as-prepared samples with the increase of nominal europium content in the reaction solution. With the increasing dopant concentration, crystallinity and crystallite size of the titania particles decreased gradually. Incorporation of europium in the titania particles induced a structural deformation and a blueshift of their absorption edge. While the room-temperature PL emission of the as-grown samples is dominated by the 5D0 - 7Fj transition of Eu+3 ions, the emission intensity reduced drastically after thermal annealing due to outwards segregation of dopant ions.

View PDF Chat

Long persistent phosphors—from fundamentals to applications

2016-01-01

Yang Li , Mindaugas Gecevičius , Jianrong Qiu

We present multidisciplinary research on synthetic methods, afterglow mechanisms, characterization techniques, material kinds, and applications of long persistent phosphors. We present multidisciplinary research on synthetic methods, afterglow mechanisms, characterization techniques, material kinds, and applications of long persistent phosphors.

Recent Progress in Rare Earth Micro/Nanocrystals: Soft Chemical Synthesis, Luminescent Properties, and Biomedical Applications

2013-12-18

Shili Gai , Chunxia Li , Piaoping Yang +1 more

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTRecent Progress in Rare Earth Micro/Nanocrystals: Soft Chemical Synthesis, Luminescent Properties, and Biomedical ApplicationsShili Gai†‡, Chunxia Li†, Piaoping Yang*‡, and Jun Lin*†View Author Information† State Key Laboratory … ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTRecent Progress in Rare Earth Micro/Nanocrystals: Soft Chemical Synthesis, Luminescent Properties, and Biomedical ApplicationsShili Gai†‡, Chunxia Li†, Piaoping Yang*‡, and Jun Lin*†View Author Information† State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China‡ Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, Harbin Engineering University, Harbin, 150001, P. R. China*E-mail: [email protected]*E-mail: [email protected]Cite this: Chem. Rev. 2014, 114, 4, 2343–2389Publication Date (Web):December 18, 2013Publication History Received13 March 2013Published online18 December 2013Published inissue 26 February 2014https://pubs.acs.org/doi/10.1021/cr4001594https://doi.org/10.1021/cr4001594review-articleACS PublicationsCopyright © 2013 American Chemical SocietyRequest reuse permissionsArticle Views25384Altmetric-Citations1232LEARN 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:Biological imaging,Ions,Luminescence,Precursors,Solvents Get e-Alerts

Upconversion Luminescent Materials: Advances and Applications

2014-12-10

Jing Zhou , Qian Liu , Wei Feng +2 more

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTUpconversion Luminescent Materials: Advances and ApplicationsJing Zhou, Qian Liu, Wei Feng, Yun Sun, and Fuyou Li*View Author Information Department of Chemistry & State Key Laboratory of Molecular … ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTUpconversion Luminescent Materials: Advances and ApplicationsJing Zhou, Qian Liu, Wei Feng, Yun Sun, and Fuyou Li*View Author Information Department of Chemistry & State Key Laboratory of Molecular Engineering of Polymers & Collaborative Innovation Center of Chemistry for Energy Materials, Fudan University, Shanghai 200433, P. R. China*Fax: 86-21-55664621. Tel: 86-21-55664185. E-mail: [email protected]Cite this: Chem. Rev. 2015, 115, 1, 395–465Publication Date (Web):December 10, 2014Publication History Received1 September 2013Published online10 December 2014Published inissue 14 January 2015https://pubs.acs.org/doi/10.1021/cr400478fhttps://doi.org/10.1021/cr400478freview-articleACS PublicationsCopyright © 2014 American Chemical SocietyRequest reuse permissionsArticle Views47956Altmetric-Citations1809LEARN 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-AlertscloseSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Absorption,Biological imaging,Lanthanides,Luminescence,Nanoparticles Get e-Alerts

Advances in Phosphors for Light-emitting Diodes

2011-05-11

Chun Che Lin , Ru‐Shi Liu

Light-emitting diodes (LEDs) are excellent candidates for general lighting because of their rapidly improving efficiency, durability, and reliability, their usability in products of various sizes, and their environmentally friendly constituents. … Light-emitting diodes (LEDs) are excellent candidates for general lighting because of their rapidly improving efficiency, durability, and reliability, their usability in products of various sizes, and their environmentally friendly constituents. Effective lighting devices can be realized by combining one or more phosphor materials with chips. Accordingly, it is very important that the architecture of phosphors be developed. Although numerous phosphors have been proposed in the past several years, the range of phosphors that are suitable for LEDs is limited. This work describes recent progress in our understanding of the prescription, morphology, structure, spectrum, and packaging of such phosphors. It suggests avenues for further development and the scientific challenges that must be overcome before phosphors can be practically applied in LEDs.

View PDF Chat

Two-Photon Excitation in Ca<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">F</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>:<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Eu</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>

1961-09-15

W. Kaiser , C. G. B. Garrett

Upconverting Nanoparticles

2011-05-30

Markus Haase , Helmut Schäfer

Abstract Upconversion (UC) refers to nonlinear optical processes in which the sequential absorption of two or more photons leads to the emission of light at shorter wavelength than the excitation … Abstract Upconversion (UC) refers to nonlinear optical processes in which the sequential absorption of two or more photons leads to the emission of light at shorter wavelength than the excitation wavelength (anti‐Stokes type emission). In contrast to other emission processes based on multiphoton absorption, upconversion can be efficiently excited even at low excitation densities. The most efficient UC mechanisms are present in solid‐state materials doped with rare‐earth ions. The development of nanocrystal research has evoked increasing interest in the development of synthesis routes which allow the synthesis of highly efficient, small UC particles with narrow size distribution able to form transparent solutions in a wide range of solvents. Meanwhile, high‐quality UC nanocrystals can be routinely synthesized and their solubility, particle size, crystallographic phase, optical properties and shape can be controlled. In recent years, these particles have been discussed as promising alternatives to organic fluorophosphors and quantum dots in the field of medical imaging.

Optical Spectroscopy of Inorganic Solids

1990-10-01

B. E. Henderson , G. F. Imbusch

1. Spectroscopy and Electronic Structure of Inorganic Solids 2. Energy Levels of Free Atoms and of Optical Centres in Crystals 3. Symmetry and Group Representation Theory 4. Radiative Transition Rates … 1. Spectroscopy and Electronic Structure of Inorganic Solids 2. Energy Levels of Free Atoms and of Optical Centres in Crystals 3. Symmetry and Group Representation Theory 4. Radiative Transition Rates and Selection Rules 5. Electronic Centres in a Vibrating Crystalline Environment 6. Experimental Techniques 7. Colour Centres in Ionic Crystals 8. Spectroscopy of Lanthanide (rare-earth) and Actinide Ions in Solids 9. Optical Streptroscopy of Transition Metal Ions in Solids 10. Spectroscopy at High Dopant Concentrations 11. Solid State Lasers 12. Optical Detection of Magnetic Resonance

Photon Correlations

1963-02-01

Roy J. Glauber

Received 27 December 1962DOI:https://doi.org/10.1103/PhysRevLett.10.84©1963 American Physical Society Received 27 December 1962DOI:https://doi.org/10.1103/PhysRevLett.10.84©1963 American Physical Society

Luminescence nanothermometry

2012-01-01

Daniel Jaque , Fiorenzo Vetrone

The current status of luminescence nanothermometry is reviewed in detail. Based on the main parameters of luminescence including intensity, bandwidth, bandshape, polarization, spectral shift and lifetime, we initially describe and … The current status of luminescence nanothermometry is reviewed in detail. Based on the main parameters of luminescence including intensity, bandwidth, bandshape, polarization, spectral shift and lifetime, we initially describe and compare the different classes of luminescence nanothermometry. Subsequently, the various luminescent materials used in each case are discussed and the mechanisms at the root of the luminescence thermal sensitivity are described. The most important results obtained in each case are summarized and the advantages and disadvantages of these approaches are discussed.

Mechanical metallurgy

1962-04-01

Preparation and performance analysis of GdInO3:Eu3+ phosphor for solid state lighting applications

2025-06-25

Yuanyuan Lu , Zhao Li , Yan Zhang +3 more | Chemical Papers

Novel Cerium- and Terbium-Doped Gadolinium Fluoride Nanoparticles as Radiosensitizers with Pronounced Radiocatalytic Activity

2025-06-24

Nikita A. Pivovarov , Danil D. Kolmanovich , Nikita N. Chukavin +7 more | Biomedicines

Background: The use of nanoradiosensitizers is a promising strategy for the precision enhancement of tumor tissue damage during radiotherapy. Methods: Here, we propose a novel biocompatible theranostic agent based on … Background: The use of nanoradiosensitizers is a promising strategy for the precision enhancement of tumor tissue damage during radiotherapy. Methods: Here, we propose a novel biocompatible theranostic agent based on gadolinium fluoride doped with cerium and terbium (Gd0.7Ce0.2Tb0.1F3 NPs), which showed pronounced radiocatalytic activity when exposed to photon or proton beam irradiation, as well as remarkable MRI contrast ability. A scheme for the production of biocompatible colloidally stable Gd0.7Ce0.2Tb0.1F3 NPs was developed. Comprehensive physicochemical characterization of these NPs was carried out, including TEM, SEM, XRD, DLS, and EDX analyses, as well as UV–vis spectroscopy and MRI relaxation assays. Results: Cytotoxicity analysis of Gd0.7Ce0.2Tb0.1F3 NPs in vitro and in vivo revealed a high level of biocompatibility. It was shown that Gd0.7Ce0.2Tb0.1F3 NPs effectively accumulate in MCF-7 tumor cells. A study of their radiosensitizing activity demonstrated that the combined effect of Gd0.7Ce0.2Tb0.1F3 NPs and X-ray irradiation leads to a dose-dependent decrease in mitochondrial membrane potential, a sharp increase in the level of intracellular ROS, and the subsequent development of radiation-induced apoptosis. Conclusions: This outstanding radiosensitizing effect is explained by the radiocatalytic generation of reactive oxygen species by the nanoparticles, which goes beyond direct physical dose enhancement. It emphasizes the importance of evaluating the molecular mechanisms underlying the sensitizing effectiveness of potential nanoradiosensitizers before choosing conditions for their testing in in vivo models.

Sensitive Thermometry through Upconversion of Er3+, Yb3+ Codoped Silicate KLaSiO4

2025-06-24

Bartosz Bondzior , Nadiia Rebrova | The Journal of Physical Chemistry C

Simultaneous Tailoring of Robust Anti‐Thermal Quenching and High Thermometric Sensitivity in Lanthanide‐Doped Cs2NaYF6 Double Perovskites

2025-06-24

Kejie Li , Mochen Jia , Jiaqi Zhao +4 more | Laser & Photonics Review

Abstract Lanthanide‐doped double perovskites have emerged as promising candidates for remote optical thermometry owing to their pronounced thermally quenched photoluminescence. However, substantial emission attenuation at elevated temperatures poses a challenge … Abstract Lanthanide‐doped double perovskites have emerged as promising candidates for remote optical thermometry owing to their pronounced thermally quenched photoluminescence. However, substantial emission attenuation at elevated temperatures poses a challenge to achieving high measurement precision. Herein, a facile solid‐state synthesis of efficient lanthanide‐doped fluoride double perovskites Cs 2 NaYF 6 , is reported presenting robust anti‐thermal quenching behavior while maintaining enhanced thermal sensitivity through partial substitution of Na + with Li + . Li + doping induces lattice contraction and increased stiffness, reducing phonon energy and suppressing electron–phonon coupling, thereby enhancing emission intensity and mitigating the thermal quenching of Er 3+ . Meanwhile, Li + ‐induced local symmetry distortion around Er 3+ leads to further Stark splitting of 2 H 11/2 , promoting the thermally assisted population of green‐emitting levels, which retain 84% of their initial intensity at 523 K. In contrast, the red emission remains unaffected due to the large energy gap between adjacent levels. Consequently, both thermally coupled and non‐thermally coupled thermometric sensitivity are enhanced, with a maximum improvement of up to 6‐fold, leading to a substantial reduction in temperature uncertainty at high temperatures. Furthermore, the practical applicability of flexible polydimethylsiloxane‐based optical fiber and thin‐film temperature sensors is demonstrated. This provides insights into simultaneously optimizing the intensity and sensitivity of luminescent thermometers.

Radiative association of the magnesium sulfide (MgS) molecule

2025-06-23

Qiuping Wei , Yang Chen , Lidan Xiao +3 more | Astronomy and Astrophysics

Addressing the formation for MgS, a relevant astrophysical problem for carbon rich stars, we have employed quantum mechanical ab initio calculations to predict the radiative association cross section and association … Addressing the formation for MgS, a relevant astrophysical problem for carbon rich stars, we have employed quantum mechanical ab initio calculations to predict the radiative association cross section and association rate coefficient of magnesium and sulfur atoms forming the magnesium sulfide molecule. This was accomplished by accounting for the emissive 1^1Π to X^1Σ^+, 1^1Δ to 1^1Π, and 1^3Σ^-toa^3Π transitions that make significant contributions to the radiative association process. The atomic ground state, Mg(^1S), and the metastable excited state, S(^1D), represent the lowest singlet dissociation limit common for the studied radiative association channels, whereas the ground states Mg(^1S) and S(^3P) represent the lowest triplet dissociation limit for these channels. The computational results show that in the temperature range of 10-10000 K, the 1^1Π to X^1Σ^+ transition dominates the formation of MgS through radiative association in the collision of Mg(^1S) and S(^1D) atoms, while the 1^1Δ to 1^1Π transition plays an important role at higher temperatures. The total rate coefficient for the singlet-singlet transitions ranges from 3.78 times 10^-^1^8 cm^3s^-^1 to 4.79 times 10^-^1^7 cm^3s^-^1, while that for the triplet-triplet transition ranges from 2.02 times 10^-^2^2 cm^3s^-^1 to 6.79 times 10^-^1^8 cm^3s^-^1. These total rate coefficients were fit using the three-parameter fit Arrhenius-Kooij function, which is expected to be helpful for the celestial modeling.

Twitching inherent properties of Sm3+ ions doped BaZrO3 nanophosphors for optoelectronic application

2025-06-23

J. Abimalar , S. Adline Benila , V. Anslin Ferby | Materials Science in Semiconductor Processing

Ion emission efficiency of Ag+ ions from silver ion-conducting glass under atmospheric pressure

2025-06-23

Daigo Ito , Daisuke Urushihara , Yusuke Daiko | Solid State Ionics

Effect of Al3+ ion on photoluminescence of Y2WO6:Nd3+ phosphor for near infra-red applications

2025-06-23

Ashvini Pusdekar , Nilesh S. Ugemuge , P. K. Singh +3 more | Emergent Materials

Europium(II) Activated Blue–Cyan Aluminosilicate Phosphors with Zero Thermal Quenching

2025-06-23

Xinzhe Zhou , Mingyu Yao , Zixuan Li +4 more | Inorganic Chemistry

The ″cyan gap″ is the bottleneck of full-visible-spectrum white light-emitting diodes (WLEDs), and the development of high thermal stability blue-cyan phosphors plays a decisive role in compensating for the cyan … The ″cyan gap″ is the bottleneck of full-visible-spectrum white light-emitting diodes (WLEDs), and the development of high thermal stability blue-cyan phosphors plays a decisive role in compensating for the cyan gap. Herein, we report a blue-cyan-emitting celsian phosphor prepared using Ba2+-doped LTA/FAUX zeolite. Excited by UV light, celsian phosphors show a super broad emission at the blue-cyan range with a full width at half-maximum (fwhm) more than 100 nm, the broadband emission effectively eliminates the cyan gap and has excellent thermal quenching resistance (120% @ 25 °C). A full-visible-spectrum WLED device prepared using the phosphor exhibits a color rendering index as high as 93, exhibiting great advantages in WLEDs. These studies not only show great promise of celsian phosphor as a blue-cyan emitter but also open the way for the preparation of suitable phosphors in zeolite materials.

Temperature-dependent luminescence and defect centre analysis of thermally stable cerium-doped aluminosilicate phosphors

2025-06-23

Vidya Saraswathi A , N. Karunakara , Vikash Mishra +5 more | Chemical Papers

Recent advances in lanthanide-doped upconversion nanoparticles for optical anticounterfeiting: Challenges and opportunities toward practical implementation

2025-06-23

S. Rajkumar , Zhuoya Zhao , Cong Liu +2 more | Coordination Chemistry Reviews

Electronic and dielectric properties of rare‐earth oxides in visible and near‐infrared range: A first‐principles study

2025-06-22

Juan Wang , Yixiu Luo , Zhen Tong +3 more | Journal of the American Ceramic Society

Abstract The widespread application of laser technology has increased the demand for laser‐protective materials, and rare‐earth oxides are potential materials in laser protection research due to their unique physical and … Abstract The widespread application of laser technology has increased the demand for laser‐protective materials, and rare‐earth oxides are potential materials in laser protection research due to their unique physical and optical properties. This study investigates the electronic structure, dielectric, and optical properties of a series of cubic rare‐earth sesquioxides (RE 2 O 3 , RE = Gd, Dy, Er, Yb, Lu, Sc, and Y) using first‐principles calculations. The dielectric and optical properties of RE 2 O 3 materials in the visible‐to‐near‐infrared (VIS‒NIR) wavelength range are clarified to be governed by electronic transitions. Despite similar spectral characteristics, the peaks in the spectra of dielectric function, complex refractive index, reflectance, and absorption coefficient systematically exhibit blue shifts with increasing RE 3+ cationic radius in the same group, or decreasing RE 3+ cationic radius in the same period, which is inherited from the variation in band gap size. And, a guideline to search for RE 2 O 3 materials with high reflectance in the NIR wavelength range is proposed to be correlated with high refractive index and low band gap. These findings elucidate the fundamental mechanisms governing the dielectric and optical properties of rare‐earth oxides within the VIS‒NIR range, and provide useful guidelines for the screening and optimizing RE 2 O 3 ‐based materials for laser‐protective applications.

Bir Gama Spektrometresinde Farklı Sintilator ve Ana Yükseltici Kullanımının Dedeksiyon Performansına Etkisinin Araştırılması

2025-06-21

Buket Canbaz Öztürk , C. Çeliktaş | Kırklareli Üniversitesi Mühendislik ve Fen Bilimleri Dergisi

Bu çalışmada, hızlı cevap süresine ve yüksek ışık verimine sahip CsI(Tl) sintilasyon kristali, yeni nesil bir fotoçoğaltıcı tüpe montajlanarak yeni bir radyasyon dedektör sistemi tasarlanmıştır. Söz konusu dedektör, gama spektroskopisi … Bu çalışmada, hızlı cevap süresine ve yüksek ışık verimine sahip CsI(Tl) sintilasyon kristali, yeni nesil bir fotoçoğaltıcı tüpe montajlanarak yeni bir radyasyon dedektör sistemi tasarlanmıştır. Söz konusu dedektör, gama spektroskopisi uygulamalarında kullanılmak üzere bir spektrometre sistemine entegre edilmiştir. Dedeksiyon performansının karşılaştırmalı analizini gerçekleştirmek amacıyla, NaI(Tl) sintilasyon dedektörü de aynı spektrometre altyapısında ve aynı fiziksel ortam koşullarında test edilmiştir. Deneysel çalışmalarda, farklı enerjilerde gama fotonları yayan iki farklı standart radyasyon kaynağı, (Cs-137 ve Co-60) kullanılarak her iki dedektörün net enerji spektrumları elde edilmiştir. Spektral çözünürlükleri optimize etmek amacıyla, iki farklı ana yükseltici modeli (ORTEC 451 ve 485) tasarlanan spektrometre sisteminde kullanılmış ve bu yükselticilerin enerji spektrumu üzerindeki etkileri incelenmiştir. Elde edilen spektrumlar, enerji çözünürlüğü ve dedeksiyon verimliliği gibi temel nicelikler açısından karşılaştırılmıştır. Sonuçlar, 451 model ana yükseltici ve CsI(Tl) kristalli kullanılarak oluşturulan spektrometrenin, özellikle yüksek sayım oranı gerektiren uygulamalarda alternatif bir çözüm potansiyeline sahip olduğunu göstermiştir.

Illuminating Innovations: A Comprehensive Review of Rare Earth-Doped Phosphors and Their Applications in LEDs

2025-06-21

Dinesh Kumar Patel , Vipin Kumar Sharma | Transactions of the Indian Institute of Metals

Ultrahigh Efficiency LiAlGa4O8: Cr3+, Ni2+ Near-Infrared Phosphor with an External Photoluminescence Quantum Yield Exceeding 70% via Cr3+–Ni2+ Energy Transfer

2025-06-20

Wendong Nie , Sisi Liang , Dejian Chen +7 more | ACS Applied Materials & Interfaces

Ni2+-doped inorganic crystals are promising for generating broadband emissions from 1000 to 1700 nm, which are crucial for advancing NIR light sources. However, their commercial applications have been hindered due … Ni2+-doped inorganic crystals are promising for generating broadband emissions from 1000 to 1700 nm, which are crucial for advancing NIR light sources. However, their commercial applications have been hindered due to their weak absorption. Herein, the LiAl5O8 crystal is present as the host for Cr3+ and Ni2+ ions due to its high density of available doping sites (Al3+) per unit volume (0.048/Å3) for Cr3+ sensitizers. By heavily increasing the doping concentration of Cr3+, an unprecedented broad emission band peaking at 773 nm emerges, enhancing the spectral overlap between the emission of Cr3+ and absorption of Ni2+, thus boosting the energy transfer efficiency from Cr3+ to Ni2+. This accelerated energy transfer rate competes favorably against nonradiative processes, allowing higher concentrations of Cr3+ without any photoluminescence quenching. Moreover, by substituting Ga3+ for Al3+, the excitation peak is successfully tuned from 405 to 445 nm, aligning perfectly with commercial blue diode chips. As a result, the optimal LiAlGa4O8: 0.26Cr3+, 0.1Ni2+ phosphor exhibits a broadband emission ranging from 950 to 1600 nm, achieving internal/external photoluminescence quantum yields up to 94.12 and 72.62%, respectively. The application demonstration of packaged lighting devices shows its great potential in the fields of poultry farming and life science.

Enhanced Visualization of Erythrocytes Through Photoluminescence Using NaYbF4:Yb3+,Er3+ Nanoparticles

2025-06-20

Vivian Torres Vera , Lorena Coronado , Ana Patricia Valencia +6 more | Biosensors

Rare-earth nanoparticles (RE-NPs), particularly NaYF4:Yb3+,Er3+, have emerged as a promising class of photoluminescent probes for bioimaging and sensing applications. These nanomaterials are characterized by their ability to absorb low-energy photons … Rare-earth nanoparticles (RE-NPs), particularly NaYF4:Yb3+,Er3+, have emerged as a promising class of photoluminescent probes for bioimaging and sensing applications. These nanomaterials are characterized by their ability to absorb low-energy photons and emit higher-energy photons through an upconversion luminescence process. This process can be triggered by continuous-wave (CW) light excitation, providing a unique optical feature that is not exhibited by native biomolecules. However, the application of upconversion nanoparticles (UCNPs) in bioimaging requires systematic optimization to maximize the signal and ensure biological compatibility. In this work, we synthesized hexagonal-phase UCNPs (average diameter: 29 ± 3 nm) coated with polyacrylic acid (PAA) and established the optimal conditions for imaging human erythrocytes. The best results were obtained after a 4-h incubation in 100 mM HEPES buffer, using a nanoparticle concentration of 0.01 mg/mL and a laser current intensity of 250–300 mA. Under these conditions, the UCNPs exhibited minimal cytotoxicity and were found to predominantly localize at the erythrocyte membrane periphery, indicating surface adsorption rather than internalization. Additionally, a machine learning model (Random Forest) was implemented that classified the photoluminescent signal with 80% accuracy and 83% precision, with the signal intensity identified as the most relevant feature. This study establishes a quantitative and validated protocol that balances signal strength with cell integrity, enabling robust and automated image analysis.

Effect of CaO Content on the Photoluminescence Excitation and Emission Properties of Bi2O3 and ZnO-Co-Doped Ca2+xGa4O8+x Phosphors

2025-06-20

Shu-Han Liao , Xiaoyu Cheng , F.-L. Hsu +2 more | Photonics

The synthesis process employed solid-state reaction methods to produce phosphors with varying CaO contents, specifically at x values of 0, 0.2, 0.4, 0.6, 0.8, and 1.0. As the CaO content … The synthesis process employed solid-state reaction methods to produce phosphors with varying CaO contents, specifically at x values of 0, 0.2, 0.4, 0.6, 0.8, and 1.0. As the CaO content (represented by the x value) increases, the crystalline structure of Ca2+xGa4O8+x + 0.01 Bi2O3 + 0.07 ZnO compositions underwent notable transformations. X-ray diffraction was used to characterize these structural changes, and we found that CaGa2O4, CaO, Ga2O3, and Ca3Ga4O9 were clearly identified. The diffraction intensities of CaGa2O4 and CaO phases increased and those of Ga2O3 and Ca3Ga4O9 decreased with the x value. Our findings revealed that the photoluminescence excitation (PLE) spectra consistently peak around 340 nm across all samples, while the photoluminescence emission (PL) spectra exhibited slight variations within the range of 474–477 nm. Most notably, the intensity of both PLE and PL spectra demonstrated a non-linear relationship with CaO content, initially increasing with higher CaO concentration, reaching maximum intensity at x = 0.4, and subsequently decreasing as the x value continued to rise. This research provides valuable insights into the relationship between composition, crystal structure, and luminescent behavior in Ca2+xGa4O8+x phosphor systems, and the theoretical mechanisms underlying these observed trends were thoroughly discussed.

Modulation of up-conversion luminescence properties by poling and Er3+ doping of KNN-based ceramics

2025-06-20

Kexin Zhao , Xin Wang , Weixuan Luo +3 more | Journal of Advanced Dielectrics

Near-unity quantum efficiency and remarkable anti-thermal quenching of Cr3+-activated Gd3AlGa4O12 garnet emitter for advanced broadband NIR light source

2025-06-19

Di Qian , Yahong Jin , Haoyi Wu +1 more | Journal of Luminescence

Mn-Doped Ag2S Quantum Dots-Fluoride Hybrid Nanostructure for High-Sensitivity NIR-II Ratiometric Thermometry

2025-06-19

Hongliang Zhu , Zhengying Du , Denghao Li +6 more | Journal of Luminescence

Exploring the thermoluminescence properties of terbium doped Mg5(BO3)3F phosphors for gamma dosimetry

2025-06-18

Preeti Padhye Kulkarni , Kishor H. Gavhane , Sandhya Deshmukh +3 more | Journal of Radioanalytical and Nuclear Chemistry

Quantum cutting tuned by Mo/W content in Er3+/Yb3+ co-doped continuous solid solution NaY(Mo W1-O4)2

2025-06-18

Xuezhu Sha , Xin Chen , Xizhen Zhang +7 more | Journal of Alloys and Compounds

Optical nonlinearities in excess of 500 through sublattice reconstruction

2025-06-18

Jiaye Chen , Chang Liu , Shibo Xi +4 more | Nature

Blue light-excited zero-thermal-quenching near-infrared garnet CaY2Sc2Al2SiO12:Cr3+/Yb3+ phosphors for pc-LED application

2025-06-18

Zhichao Ren , Hongquan Yu , Xin Tong +5 more | Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy

Insights about defects in rare earth-doped Sr4Al14O25 via a classical computational modelling approach.

2025-06-18

Giordano Frederico da Cunha Bispo , Adriano B. Andrade , Eduily Benvindo Vaz Freire +4 more | Physica B Condensed Matter

Thermoluminescence characteristics of Mn doped SrAl2O4 phosphor

2025-06-17

N.R. Thejavathi , H.S. Lokesha , K.R. Nagabhushana +2 more | Physica Scripta

Abstract The structure and thermoluminescence (TL) characteristics of beta-irradiated Mn (1%)-doped SrAl2O4 have been investigated. The sample was synthesized by the solution combustion method. Rietveld refined X-ray diffraction pattern of … Abstract The structure and thermoluminescence (TL) characteristics of beta-irradiated Mn (1%)-doped SrAl2O4 have been investigated. The sample was synthesized by the solution combustion method. Rietveld refined X-ray diffraction pattern of SrAl2O4:Mn reveals that the sample is predominantly in monoclinic phase with space group P21. The average crystallite size is 27 nm, estimated from the size-strain plot (SSP) method. Electron paramagnetic resonance showed that valence state Mn ions in SrAl2O4 are 2+. TL glow curve of beta irradiated (50 Gy) SrAl2O4:Mn shows two prominent peaks reproducible at 120 ± 1 C and 350 ± 2 C. The peaks overlapped in the TL glow curve is assessed using Tm-Tstop method. Here, kinetic parameters of the prominent peak (120 C) were estimated from the whole glow peak, variable heating rate (VHR) and glow curve deconvolution methods. The activation energy of the peak at 120 C is 0.89 eV calculated using the VHR method. The activation energy of thermal quenching of the peak at 120 C is found to be 1.12 ± 0.05 eV. This report educates the TL properties of SrAl2O4:Mn and its kinetic analysis.

Blue Light Fluorescence in Marine Sediments

2025-06-17

Emily Carter Jones , Kelsey A. Williams , Ervan G. Garrison +1 more | Geosciences

Mineral fluorescence under different portions of the visible and invisible light spectrum has a long history of scientific study. In our study of marine sediments from the Georgia Bight, we … Mineral fluorescence under different portions of the visible and invisible light spectrum has a long history of scientific study. In our study of marine sediments from the Georgia Bight, we have utilized the blue portion of the light spectrum in the 445 nanometer (nm) range. The use of fluorescence has proven very useful in microscopic analyses of carbonate minerals. While the sediment prism of the inner-to-mid continental shelf in the southeastern Atlantic is predominantly siliceous, the dissolution and deterioration of marine shell contribute a significant amount to the fabric of any sediment sample. Together with carbonate minerals such as dolomite, eroded from basement rock and redeposited on the shelf, a potentially robust fluorescent response was expected and observed in samples. In marine sediments, blue light illumination has produced an easily observed fluorescent response in both underwater and in laboratory settings. This fluorescence can be attributed to carbonate minerals—calcite/aragonite. Feldspars are major accessory minerals in the sediment prism of the Georgia Bight, and much of the observed fluorescence in our samples can be attributed to their presence. To identify specific minerals responsible for any observed fluorescence, X-ray diffraction and energy dispersive spectroscopy were utilized. This combined methodology of luminescent excitation, X-ray diffractometry and spectroscopy has produced the results reported herein.

Cationic Substitution-Enabled Green-Emitting Gd2–yYyLuAl4GaO12: Ce3+ Garnet Phosphors with High Quantum Efficiency and Superior Thermal Stability for Advanced WLEDs

2025-06-17

Dan Zhang , Taifang Zhang , Mekhrdod Kurboniyon +2 more | Inorganic Chemistry

A novel garnet-type phosphor, Gd2-yYyLuAl4GaO12: Ce3+, was synthesized via a high-temperature solid-state reaction to address the demand for efficient green-emitting materials in solid-state lighting. By employing a cation substitution strategy … A novel garnet-type phosphor, Gd2-yYyLuAl4GaO12: Ce3+, was synthesized via a high-temperature solid-state reaction to address the demand for efficient green-emitting materials in solid-state lighting. By employing a cation substitution strategy (Y3+/Gd3+ codoping), the photoluminescence performance was significantly enhanced: the quantum efficiency increased from 86.79 to 96.86%, accompanied by a tunable emission shift from yellow to green (560-520 nm). Moreover, the thermal stability at 423 K improved dramatically from 40.79 to 92.98%, surpassing those of commercial green phosphors. Structural and spectral analyses revealed that the optimized crystal field splitting and enhanced lattice rigidity, induced by cation substitution, effectively suppressed nonradiative transitions, thereby boosting both quantum efficiency and thermal stability. A prototype white light-emitting diode (WLED) fabricated with Y2LuAl4GaO12: Ce3+ phosphor exhibited excellent performance, including a high color rendering index (Ra = 91), low correlated color temperature (CCT = 3043 K), and good color stability under varying driving currents. These findings highlight the significant promise of Gd2-yYyLuAl4GaO12: Ce3+ as a superior green-emitting phosphor for advanced WLED systems, providing a feasible pathway for designing outstanding thermal stability and color-tunable luminescent materials via cationic engineering.

Ultra‐Sensitive Low‐Temperature Upconversion via Interfacial Energy Transfer Toward Visual Cryogenic Nanothermometry

2025-06-17

Haopeng Wei , Zhiyuan Cai , Haozhang Huang +2 more | Advanced Functional Materials

Abstract Nanothermometry with high resolution and sensitivity shows significant potential for both fundamental research and frontier applications. However, achieving real‐time high‐sensitivity temperature sensing in low‐temperature regions at the single nanoparticle … Abstract Nanothermometry with high resolution and sensitivity shows significant potential for both fundamental research and frontier applications. However, achieving real‐time high‐sensitivity temperature sensing in low‐temperature regions at the single nanoparticle level has remained challenging. Here a conceptual strategy is reported to realize the ultra‐sensitive low‐temperature thermoresponsive upconversion by interfacial energy transfer in a core‐shell nanostructure. The nanoscale spatial separation of the sensitizer Yb 3+ and activator Ho 3+ contributes to a remarkable enhancement of the upconversion by suppressing back energy transfer channels in addition to a temporal control of upconversion dynamics. Moreover, the design of non‐thermally coupled upconverting system results in highly sensitive thermochromic upconversion emissions with a contrast red‐to‐green color change and the relative sensitivity is raised up to 15.1% K −1 at 50 K. Furthermore, the sensing limit can be extend above room temperature to 443 K by incorporating another temperature‐responsive Yb 3+ /Tm 3+ layer through a multi‐layer core‐shell architecture design. These findings gain a deep insight into the thermoresponsive upconversion in nanoparticles but also provide a new way for the development of ultrasensitive real‐time visual nanothermometry and other thermoresponsive devices.

Effects of Geometric Isomerism and Crystal Size on Ultra-Narrowband Near Infrared Emission from Organic Crystals

2025-06-16

Hao Zhang , Linfeng Lan , Baolei Tang +3 more | CCS Chemistry

Charge Transfer State: A New Sensitization Route for Blue‐LED‐Excitable Near‐Infrared Phosphors

2025-06-16

Limin Wei , Jindou Huang , Hong Wang +6 more | Laser & Photonics Review

Abstract Blue‐LED‐excitable Near‐infrared (NIR) phosphors doped with transition metal or rare‐earth ions hold great promise for next‐generation NIR light sources in phosphor‐converted LEDs (pc‐LEDs). However, current blue‐excitable NIR phosphors mainly … Abstract Blue‐LED‐excitable Near‐infrared (NIR) phosphors doped with transition metal or rare‐earth ions hold great promise for next‐generation NIR light sources in phosphor‐converted LEDs (pc‐LEDs). However, current blue‐excitable NIR phosphors mainly rely on Cr 3+ ion absorption, which involves forbidden transitions with limited efficiency. Here an allowed charge‐transfer (CT) transition is proposed as a novel sensitization route for blue‐LED‐excitable NIR phosphors. The broad sensitization band arising from the S 2− →Yb 3+ CT in NaLaS 2 :Yb 3+ fully covers the entire blue wavelength region. Under 450 nm excitation, it exhibits intense NIR emission centered at 994 nm, with an internal quantum efficiency of 64%. This allows CT transition, with high absorption efficiency, leads to a notable external quantum efficiency of 45%. At 420 K, the emission intensity maintains 88.7% of that at room temperature. Coupled with a blue chip, a high‐performance NIR pc‐LED is fabricated with a photoelectric conversion efficiency of 15.5% and demonstrates its potential applications. These findings open new and efficient sensitization avenues for blue‐LED‐excitable phosphors.

High-Purity Deep Red Emission of Cr3+-Doped YAlO3 Solid Solution with Perovskite Structure for Plant Growth

2025-06-16

Mengyu Zhang , Chong Li , Wenzhi Su +6 more | ACS Applied Optical Materials

NH4+‐Induced Formation of Hexagonal‐K1.5(NH4+)0.5SiF6:Mn4+ with Polarized Zero‐Phonon Line Emission

2025-06-16

Zeyu Lyu , Hongbin Zhao , Hao Dong +6 more | Laser & Photonics Review

Abstract Polarized luminescence is extensively applied in many cutting‐edge areas, implying the practical significance of exploring the polarization behavior of various emitters. Herein, for the first time, the polarized emission … Abstract Polarized luminescence is extensively applied in many cutting‐edge areas, implying the practical significance of exploring the polarization behavior of various emitters. Herein, for the first time, the polarized emission of Mn 4+ ion is disclosed in a hexagonal K 2 SiF 6 matrix, which is obtained through the NH 4 + ‐induced phase transition from the cubic counterpart. The exact component of the hexagonal matrix is determined to be K 1.5 (NH 4 ) 0.5 SiF 6 . After doping Mn 4+ , the K 1.5 (NH 4 ) 0.5 SiF 6 :Mn 4+ exhibits intensive zero‐phonon line (ZPL) emission. Importantly, the ZPL emission shows a linear polarization with a degree of polarization (DOP) of 0.65, and its polarization direction is aligned with the c ‐axis of the crystal. The polarization behavior arises from the Mn 4+ ions occupying lattice sites with anisotropic structure along the c ‐axis. The rest of Mn 4+ ‐emissions, which incorporate phonons, show the same polarization direction but with much weaker polarization (DOP ≈ 0.1). Moreover, when excited by the 488 nm light propagating perpendicularly to the crystal c ‐axis, all the emissions show a periodic fluctuation with the polarized angle of excitation. This work conducts a pioneering and detailed study of the polarization behavior of Mn 4+ ‐emission in a newly established hexagonal fluoride, opening up the research of polarized luminescence in the abundant Mn 4+ ‐doped phosphors.

The Temperature Imaging Study Based on the Time‐Resolved Luminescence Measurement of Mn4+‐Doped Lu3Al5O12 Phosphor

2025-06-16

Liting Qiu , Qian Zhang , Zhicheng Liao +3 more | Laser & Photonics Review

Abstract Nowadays, optical thermometry with a non‐contact operation mode and fast response is crucial in micro/nano electronics. However, the existing temperature measurement methods have the problem of low sensitivity. Herein, … Abstract Nowadays, optical thermometry with a non‐contact operation mode and fast response is crucial in micro/nano electronics. However, the existing temperature measurement methods have the problem of low sensitivity. Herein, a temperature sensing method based on time‐resolved integrated intensity ratio (TRIIR) of Mn 4+ ‐doped Lu 3 Al 5 O 12 (LuAG) phosphor is proposed for the purpose of improving the temperature sensitivity of optical temperature measurement. Compared with the thermometry based on fluorescence lifetime of LuAG: Mn 4+ , the relative sensitivity () is significantly improved. Furthermore, the is further boosted by changing the experimental condition. Specifically, under the experimental condition of and , the value reaches 11.86% K −1 at 325 K, and the temperature resolution can reach 0.07 K at 310 K. At the same time, the shift of the optimal temperature measurement range toward the high‐temperature zone can be achieved by reducing . Finally, with the help of a fluorescence microscope and an ICCD camera, the temperature imaging capability of LuAG: Mn 4+ phosphor based on the TRIIR method with a high spatial resolution (2.7 µm) is verified on a nickel circuit. These results reveal that the LuAG: Mn 4+ phosphor based on the temperature sensing method of TRIIR is very promising for future temperature imaging applications.

Laser‐Induced Rare Earth Up‐Conversion Luminescent Plastics

2025-06-15

Dale Xie , Chenqi Yi , Zongsong Gan | Laser & Photonics Review

Abstract Rare earth elements‐doped glass‐ceramics have been widely studied in recent decades due to their excellent up‐conversion luminescence properties. However, the preparation method of glass‐ceramics limits its application, and it … Abstract Rare earth elements‐doped glass‐ceramics have been widely studied in recent decades due to their excellent up‐conversion luminescence properties. However, the preparation method of glass‐ceramics limits its application, and it is difficult to realize up‐conversion luminescence by laser lithography in a glass medium. Therefore, it is necessary to find new materials to replace the up‐conversion glass‐ceramics to realize in situ up‐conversion luminescence. Here, up‐conversion nanocrystals (NaYF 4 ) have been successfully in situ generated with different crystal phases in transparent plastics by using a femtosecond laser, and realize the precise tuning of the fluorescence intensity of up‐conversion luminescence. Furthermore, up‐conversion luminescence at different excitation wavelengths is realized by doping with rare earth elements such as Er, Tm, and Ho. The stability test shows that the laser‐generated up‐conversion nanocrystals inside the plastics can maintain stable up‐conversion luminescence in solvents and high temperatures. This breakthrough technology has led to the development of a variety of precisely controllable up‐conversion luminescent plastics, which provides a practical technical route for the application of new luminescent solid media.

Tunneling in Persistent Luminescence

2025-06-14

Hei‐Yui Kai , Ka‐Leung Wong , Peter A. Tanner | Advanced Optical Materials

Abstract An overview of some key points in persistent luminescence (PersL) is provided with an emphasis on tunneling phenomena. Notably, key experimental criteria are provided that can substantiate the occurrence … Abstract An overview of some key points in persistent luminescence (PersL) is provided with an emphasis on tunneling phenomena. Notably, key experimental criteria are provided that can substantiate the occurrence of thermal and athermal tunneling and localized transitions. These are elucidated by reference to a Case Study and to some other relevant works. Many experimental studies of PersL have assigned the mechanism to be tunneling on the basis of the linear relationship of PersL decay between intensity, I , and time, t −k , where k is a constant, or I −1 versus t . However, this relation also applies to the case where there is a uniform distribution of trap levels, which may be evident from the breadth of the TL peak. The key measurement for the assignment of below‐conduction band processes is the absence of thermal conductivity.

High‐Contrast Fluorescent Electrophoretic Display Based on Upconversion Fluorescent Electrophoretic Particles for Multifunctional Dynamic Anticounterfeiting Applications

2025-06-14

Feng Xiong , Guangyou Liu , Junjie He +4 more | Advanced Optical Materials

Abstract Fluorescence‐based anti‐counterfeiting (AC) technology, typically achieved through static printed images, is vulnerable to lower security and easier replication. Therefore, developing multifunctional and dynamic AC devices is crucial. The application … Abstract Fluorescence‐based anti‐counterfeiting (AC) technology, typically achieved through static printed images, is vulnerable to lower security and easier replication. Therefore, developing multifunctional and dynamic AC devices is crucial. The application of upconversion fluorescent materials to electrophoretic displays offers a promising approach to creating dynamic, multifunctional AC devices. In this work, a multifunctional AC device based on a fluorescent electrophoretic display (FEPD) is designed. By surface‐modifying commercial infrared fluorescent powder, an upconversion fluorescent electrophoretic particle (UCEP) is developed which can be driven under an electric field and emit green fluorescence under infrared light excitation. The UCEP is incorporated into black‐and‐white electrophoretic ink to fabricate the FEPD. This device exhibits a high ambient contrast ratio of 56, a fast response time of 175 ms, and the ability to switch from a white reflective state to a green luminous state under 980 nm light. These results demonstrate the potential application of the FEPD in dynamic, high‐security, and multifunctional AC devices.

Unlocking NIR‐II Photoluminescence in 2D Copper Tetrasilicate Nanosheets through Flame Spray Synthesis

2025-06-13

Robert Nißler , Quanyu Zhou , Björn Hill +7 more | Advanced Materials

Abstract Expanding fluorescence bioimaging into the second near‐infrared spectrum (NIR‐II, 1000–1700 nm) unlocks advanced possibilities for diagnostics and therapeutics, offering superior tissue penetration and resolution. 2D copper tetrasilicate (CTS) pigments … Abstract Expanding fluorescence bioimaging into the second near‐infrared spectrum (NIR‐II, 1000–1700 nm) unlocks advanced possibilities for diagnostics and therapeutics, offering superior tissue penetration and resolution. 2D copper tetrasilicate (CTS) pigments ( M CuSi 4 O 10 , M = Ca, Sr, Ba) are known for their brightness and stability, yet synthetic challenges have curbed their integration into bioimaging. Here, flame‐spray‐pyrolysis (FSP) is introduced as a versatile and scalable synthesis approach to produce ultra‐bright, metastable CTS nanosheets (NS) by annealing multi‐element metal oxide nanoparticles into 2D crystals through calcination or laser irradiation. Group‐II ion incorporation shifts emission into the NIR‐II range, with Ba 0.33 Sr 0.33 Ca 0.33 CuSi 4 O 10 peaking at 1007 nm, while minor Mg‐doping induces a hypsochromic shift and extends fluorescence lifetimes. The engineered CTS achieves quantum yields of up to 34%, supporting NS high‐frame‐rate imaging (> 200 fps). These unique properties enable CTS‐NS to serve as powerful contrast agents for super‐resolution NIR bioimaging, demonstrated in vivo through transcranial microcirculation mapping and macrophage tracking in mice using diffuse optical localization imaging (DOLI). This pioneering synthesis strategy unlocks wavelength‐tunable NS for advanced NIR‐II bioimaging applications.

Temperature‐Dependent Phase Evolution of LaVO4 via Solid‐State Synthesis Route

2025-06-13

A. K. Sivadasan , Geetha Aravindkrishna , V. Narayanan +5 more | physica status solidi (b)

Lanthanum ortho ‐vanadate (LaVO 4 ) is a wide bandgap semiconducting material suitable for various applications especially for photocatalytic activities. In most cases, the synthesis of LaVO 4 involves concentrated … Lanthanum ortho ‐vanadate (LaVO 4 ) is a wide bandgap semiconducting material suitable for various applications especially for photocatalytic activities. In most cases, the synthesis of LaVO 4 involves concentrated acidic treatments and very high reaction temperatures for long durations. The present work establishes an easy route to synthesize LaVO 4 at a relatively lower temperature and short dwelling time via solid‐state reaction of the precursors of lanthanum acetate hydrate and vanadium acetylacetonate. The thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC) analyses of the precursor mixture indicate a phase transition above 415 °C. The Rietveld structure refinement of the X‐ray diffraction data of the precursor mixture, obtained after heat treatment at 500 °C, confirms the formation of the monoclinic ( m ‐) phase of LaVO 4 corroborating the predictions from the TGA‐DSC analysis. The occurrence of internal vibrational modes related to the VO 4 tetrahedron in the Raman spectra suggests the onset of the nucleation of the m ‐LaVO 4 phase at a lower temperature. The external modes representing the vibrations of the molecule as a whole are profound at higher temperatures. The coexistence of LaO as well as VO bond vibrations observed in the Fourier transform infrared spectroscopy further confirmed the formation of bonding between the atoms of the molecule.

Eu2+/Eu3+ doped Al2O3 coatings formed on tungsten by plasma electrolytic oxidation: photoluminescent properties and application in luminescence thermometry

2025-06-13

Stevan Stojadinović , Pedro Nelson , Sanja Kuzman +3 more | Optical Materials

Flowcytometric apoptotic studies on MCF-7 human breast cancer cells by the induction of Y2O3:Er3+ nanophosphor

2025-06-12

T. S. Sreejaya , Drisya Mottammal , Deepthi N. Rajendran | Advances in Natural Sciences Nanoscience and Nanotechnology

Abstract Lanthanide doped upconverting nanomaterials have high luminescent efficiency and comparable cytotoxicity. Therefore, they are frequently employed in the biomedical imaging field. The upconverting nanomaterials are primarily utilized for imaging … Abstract Lanthanide doped upconverting nanomaterials have high luminescent efficiency and comparable cytotoxicity. Therefore, they are frequently employed in the biomedical imaging field. The upconverting nanomaterials are primarily utilized for imaging applications since their excitation occurs in the Near Infra-Red spectrum. Er 3+ in different concentrations such as 0.01, 0.02 and 0.03 were doped into Yttrium oxide were prepared by sol citrate gel method. The samples were annealed for 2 h at 600 °C. The synthesized materials’ x-ray diffraction analyses revealed a cubic phase with crystallite sizes of 6.1, 6.4, and 7.2 nm for x = 0.01, 0.02, and 0.03, respectively. Flake like morphology was obtained from the scanning electron micrographic images. transmission electron microscopic studies confirmed the structural properties. Chemical compositions were examined, and the findings demonstrated a good agreement between the calculated and experimental values. Studies using flow cytometry and double staining were performed to determine whether Y 2 O 3 : x Er 3+ induced apoptosis in MCF 7-human breast cancer cells. The findings of our investigation promote the notion that necrosis can be successfully treated with a sample at a higher concentration.

Multimode Ultrasensitive Optical Temperature Sensing Based on Upconversion Luminescence in BaNb2O6 Phosphor

2025-06-12

Xi Chen , Jing Li , Li Chen +5 more | ACS Applied Optical Materials

Optical Properties of Near-Infrared Phosphor and Its Application in the Fabrication of Broadband Wavelength Emitters

2025-06-12

Vũ Thị Hạnh Thu , Trong-Nam Tran , Quang‐Khoi Nguyen | Photonics

Herein, we study a method for developing a broad-emission emitter that can emit radiation from the visible light to NIR regions. Firstly, an NIR phosphor’s optical properties (e.g., scattering vs. … Herein, we study a method for developing a broad-emission emitter that can emit radiation from the visible light to NIR regions. Firstly, an NIR phosphor’s optical properties (e.g., scattering vs. weight concentration, conversion efficiency, and emission spectra under blue and red light excitation) are investigated. Then, pcW-LEDs encapsulated with NIR down-conversion phosphor samples are prepared to test these optical properties. The results show that pcW-LEDs encapsulated with the NIR phosphor at different weight concentrations of 10.0%, 12.5%, and 15.5%, respectively, emit a broadband emission from 400 nm to 900 nm. The EQE values of the pcW-LEDs encapsulated with NIR phosphor at weight concentrations of 10%, 12.5%, and 15.0% are 26%, 23%, and 19%, respectively. The correlated color temperatures of these samples are 5767 K, 5940 K, and 6068 K, respectively. The obtained radiant fluxes of the samples are 26 mW, 22 mW, and 18 mW, respectively, at an injection current of 50 mA.

Unusual Single Band 803 nm Persistent Luminescence of Tm-Doped Calcium Titanate Charged in the Near-Infrared Bio-Imaging Window

2025-06-12

Gulizhabaier Abulipizi , Juanjuan Zhou , Chaomin Qu +7 more | ACS Applied Materials & Interfaces

Lanthanide-doped materials were developed with interesting near-infrared (NIR) persistent luminescence (PersL) properties after X-ray irradiation but are limited by poor charging ability based upon biocompatible red light. In this study, … Lanthanide-doped materials were developed with interesting near-infrared (NIR) persistent luminescence (PersL) properties after X-ray irradiation but are limited by poor charging ability based upon biocompatible red light. In this study, CaTiO3:Tm (CTT) was found to emit an unusual single band PersL at ∼800 nm, which was rechargeable by red-NIR light excitation (∼650 to 720 nm). Moreover, blue or deep red light could charge more intense PersL than UV light in CTT, which was quite different from all the other known lanthanide-activated NIR PersL materials. An upconverting-energy transfer PersL mechanism was proposed based on the upconverting property of Tm3+ and its energy transfer to Ti3+ in the CaTiO3 matrix. The interaction of Tm3+ and Ti3+ in CaTiO3 quite possibly played an important role in the unusual PersL process of CTT, which avoided the band-pass transition of the CaTiO3 matrix. By comparison with a series of Tm-doped phosphors, CaTiO3 was found to be an optimal PersL matrix to generate the unique PersL properties of Tm3+. The in situ charged NIR PersL imaging of a medical stent implant in the neck of a chicken model was demonstrated. This study reveals the unusual PersL properties of CTT and will promote advanced biomedical applications of rare-earth-doped PersL biomaterials.

An Efficient Broadband Cyan Phosphor for Full‐Spectrum pc‐WLEDs

2025-06-11

Hang Gao , Huajun Wu , Liangliang Zhang +4 more | Laser & Photonics Review

Abstract Current phosphor‐converted white light‐emitting diodes (WLEDs) exhibit an unexpected gap in the cyan spectral range (480–520 nm), which hinders the realization of high color rendering index (CRI > 90) … Abstract Current phosphor‐converted white light‐emitting diodes (WLEDs) exhibit an unexpected gap in the cyan spectral range (480–520 nm), which hinders the realization of high color rendering index (CRI > 90) at high correlated color temperatures (CCT > 4500 K). To address this issue, the existing cyan phosphors have to be blended with at least two phosphors (yellow and red) for producing full‐spectrum WLEDs, which, however, mostly offer luminous efficiencies below 100 lm W −1 for high CRI at high CCT. In this work, a broadband cyan Lu 2 SrAl 2 Ga 2 SiO 12 : Ce 3+ garnet phosphor is developed by shifting the efficient green emission of Lu 2 SrAl 4 SiO 12 : Ce 3+ toward the blue side via 2Ga 3+ substitution for 2Al 3+ . The new cyan phosphor shows an emission band peaked at 489 nm with a bandwidth of 80 nm and internal/external quantum efficiencies of 81%/63%. More crucially, the new phosphor can be used to produce full‐spectrum pc‐WLEDs via blending with only a red phosphor. By adjusting the cyan/red phosphor ratio, full‐spectrum pc‐WLEDs with tunable CCT ranging from 3500 to 6837 K and simultaneous high CRI (>90) and high luminous efficiencies (113.7–127.3 lm W −1 ) are achieved. This research furnishes a promising cyan phosphor for applications in efficient full‐spectrum LED lighting.