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The development of high-tech anti-counterfeiting inks to detect counterfeit products is a crucial task for almost every aspect of modern life around the world. Herein, we report the synthesis of photoluminescent x Y 2 O 3 :Eu3+@PVA (x = 0, 1, 2.5, 5, 10, 15, and 20 wt%) composite dispersions and films and demonstrate their potential for anti-counterfeiting inks applications. Laser-synthesized m -Y 2 O 3 :Eu3+ nanoparticles (d aver = 20.3 ± 6.9 nm) with strong red luminescence due to 5D 0 → 7F 0-4 transitions of Eu3+ were used as a pigment to create luminescent composites. Detailed photoluminescence properties of the obtained composite dispersions and films as a function of m -Y 2 O 3 :Eu3+ content were investigated in combination with SEM, EDX, UV–Vis and IR spectroscopy data. Tuning of the CIE coordinates of x Y 2 O 3 :Eu3+@PVA is observed by changing the excitation wavelength. The results of SEM showed that the photoluminescent nanoparticles were uniformly distributed in the PVA film. Photoluminescent m -Y 2 O 3 :Eu3+-doped PVA composite inks can be applied via spray, brush, and screen-printing techniques to create security features on various surfaces, including glass, ceramics, paper, plastics, and currency notes. These inks remain stable for at least four months and offer a distinctive luminescent signature that is challenging to replicate, owing to the unique photoluminescence spectrum of Eu3+ in the monoclinic Y 2 O 3 polymorph. • Luminescent Y 2 O 3 :Eu3+@PVA composite dispersions and films were synthesized. • Laser-synthesized m -Y 2 O 3 :Eu3+ nanoparticles were used as a luminescent pigment. • The m -Y 2 O 3 :Eu3+ nanophosphor exhibits strong red emission at λ ex = 250, 365, 395 nm. • Tuning of the CIE coordinates is observed by changing the excitation wavelength. • Y 2 O 3 :Eu3+@PVA composites have potential to be used as anti-counterfeiting inks applications. [ABSTRACT FROM AUTHOR]

Near-infrared (NIR) spectroscopy technology has demonstrated unparalleled efficacy in night vision, iris authentication, plant illumination, food inspection, and various other domains. Nonetheless, the quest for novel phosphors exhibiting superior luminescent efficiency and enduring thermal stability persists as a formidable obstacle. In this study, phosphors MgGaBO 4 : Cr3+, Al3+ were successfully synthesized by high-temperature solid-phase reaction method. Firstly, starting from MgGaBO 4 : Cr3+, the crystal field environment around Cr3+ ions was modulated by replacing Ga3+ with Al3+ to further improve the luminescence performance of the phosphor. The emission peak wavelength of MgGaBO 4 : 0.0075Cr3+,0.005Al3+ phosphor was about 756 nm, the full width at half-maximum (FWHM) was about 174 nm under the blue light excitation of 440 nm. In addition, the luminescence intensity at 100 °C remains at 77.41 % of that at room temperature. Finally, the excellent moisture resistance of this phosphor was demonstrated. This work not only introduces a novel broadband NIR phosphor with promising application potential in advanced agricultural lighting but also proposes a synergistic enhancement strategy for effectively improving the performance of broadband NIR phosphor-converted LED light sources. • A novel broadband-emitting MgGaBO 4 phosphor has been synthesized. • The luminescence performance of phosphor was enhanced via a co-doping strategy and the synergistic effect of flux agents. • The broadband emission characteristic of MgGaBO 4 phosphor renders it potentially applicable in plant lighting technology. [ABSTRACT FROM AUTHOR]

Spinel-type aluminate (ZnAl 2 O 4) doped with europium (Eu) ions has garnered considerable attention in the field of luminescence. This study explores a series of Zn/BaAl 2 O 4 :0.2%Eu phosphors (x = 0∼0.25, x is for the mole fraction of BaAl 2 O 4), fabricated through a high temperature solid-phase reaction method in air or reduction environment. In the case of phosphors synthesized in air, the photoluminescence emission (PL) spectra show a series of sharp emission peaks at 570 nm, 589 nm, 620 nm, 660 nm, and 710 nm, which are generated by the 5D 0 -7F J (J = 0, 1, 2, 3, 4) level transitions in Eu3+. Time-resolved photoluminescence and X-ray photoelectron spectroscopy (XPS) characteristics also validate the presence of Eu3+ in samples synthesized in air. An intriguing observation is the abnormally strong emission peak at 570 nm under 346 nm excitation, originating from the Eu3+5D 0 -7F 0 level transition. For x = 0.15, the corresponding CIE color coordinate is (0.3246, 0.3449), suggesting its potential application as a mono-doped and uni-matrix white phosphor. On the other hand, phosphors synthesized in reduction environment exhibit PL spectra with a wide emission band spanning from 400 nm to 550 nm, resulting from the electric-dipole-allowed transition of f-d state of Eu2+. The partial substitution of Zn2+ with Ba2+ significantly enhances the Eu2+ luminescence intensity. Moreover, an elevation of the mole fraction of Zn/BaAl 2 O 4 :0.2%Eu leads to a notable redshift (450 nm→500 nm) in the emission peaks of Eu2+ caused by lattice expansion, providing the adjustability of emitting color. • An abnormally strong emission at 570 nm originating from Eu3+5D 0 -7F 0 transition was observed for phosphors prepared in air. • Corresponding CIE color coordinate is (0.3246, 0.3449) under 346 nm excitation for the phosphor (x = 0.15) prepared in air. • Notable redshift (450 nm→500 nm) in Eu2+ emission appears with elevation of x for phosphors prepared in reduction environment. • Internal quantum yield achieves 77.34% for phosphor (x = 0.15) prepared in reduction environment. [ABSTRACT FROM AUTHOR]

The intensity of upconversion luminescence (UCL) poses a significant challenge for oxides characterized by high phonon energy. Herein, a significant enhancement of red UCL is achieved through the introduction of an intermediate band (IB) in α-Ba 2 ScAlO 5 : Yb3+/Er3+ by Ca2+ ions doping. The absorption spectra verify the existence of the IB. The IB of α-Ba 2 ScAlO 5 : Yb3+/Er3+/Ca2+ increases the host's absorption of excited photons, provides more electrons for the excitation of Er3+, and realizes the enhancement of UCL emission. The optimal concentration of Ca2+ in α-Ba 2 ScAlO 5 : 0.2Yb3+, 0.03Er3+ is 0.15. Compared with undoped Ca2+ samples, the red and green UCL intensity of α-Ba 2 ScAlO 5 : Yb3+, Er3+, 0.15Ca2+ increased by 48.2 and 10.6 times, respectively. The mechanism of Ca2+ enhanced UCL was investigated by analyzing the UCL spectra, absorption spectra and lifetime decay curves of α-Ba 2 ScAlO 5 : Yb3+/Er3+/Ca2+. The temperature-dependent UCL properties of α-Ba 2 ScAlO 5 : Yb3+/Er3+/Ca2+ were also studied by the 2H 11/2 (525 nm) and 4F 9/2 (667 nm) energy level radiation transitions. The observed linear correlation between luminescence intensity and temperature, coupled with its high sensitivity, indicates the promising potential for temperature sensing applications. This study not only opens a new avenue for enhancing UCL but also holds significant implications for sparking widespread interest in non-contact temperature sensing applications leveraging UCL. [Display omitted] • α-Ba 2 ScAlO 5 :Yb3+/Er3+/Ca2+ with strong upconversion red emission was prepared by high temperature solid phase method. • A significant enhancement of UCL red is achieved through the introduction of an intermediate band. • α-Ba 2 ScAlO 5 :Yb3+/Er3+ phosphor enhances red light by 48.2 times and green light by 10.6 times after doping with Ca2+. • α-Ba 2 ScAlO 5 :Yb3+/Er3+/Ca2+ phosphor have broad application in non-contact temperature sensing applications. [ABSTRACT FROM AUTHOR]

Green syntheses employing aqueous solutions of lanthanide chloride, NaOH, and pentafluorobenzoic acid were successfully developed and produced pure dinuclear α-Ln compounds, [Ln(L) 3 (H 2 O) 4 ] 2 ·2H 2 O (L: pentafluorobenzoate) and new ones: η-Ln, Na[Ln(L) 3 (H 2 O) 4 ]·L·2H 2 O, and θ-Ln, with Ln: Eu(III), Gd(III), and Tb(III). The synthesis becomes even greener when mechanochemistry is employed because it is quantitative, solvent-free, fast (30 min), and energy efficient. The θ-Ln compounds still have unknown composition and structure, so its description and properties are not explored. The η-Ln compounds are 1-D coordination polymer with only one bridging L, which leads to a large Ln···Ln distance (6.865 Å). Heteronuclear α- Ln 0.50 Ln 0.50 ′ and η- Ln x Ln 1 − x ′ compounds, with x = 0.05, 0.25, 0.50, and 0.75, Ln, Ln ′ : Eu, Tb, and Gd, have been synthesized by mixing the proper proportion of the lanthanide chlorides in the initial solution. The η-Eu x Tb 1−x materials present Tb(III) → Eu(III) energy transfer, which confers interesting luminescent and photophysical properties with relevant potential applications. The color of the emission under UV irradiation can be tuned by the composition of the η-Eu x Tb 1−x materials as well as by the excitation wavelength. In addition, it was observed a significant increase (ca. 35–260 %) of the D 0 5 Eu(III) emission lifetime in the η-Eu x Tb 1−x compounds by varying the excitation wavelength. [Display omitted] • Green syntheses of new luminescent materials. • Pure and quantitative mechanosynthesis. • Easy control of heterometallic composition. • Energy transfer Tb(III).→Eu(III) with emission color tuning for sensors [ABSTRACT FROM AUTHOR]

Bismuth-based composite fluoride upconversion luminescent materials exhibit uniform size and excellent upconversion properties. These materials have potential applications in photodynamic therapy, anti-counterfeiting technology, and bio-imaging. Thus, bismuth-based composite fluoride luminescent materials have been the subject of extensive study in recent years. This paper focuses on the design and synthesis of bismuth-based composite fluorides, specifically Yb3+/Er3+ co-doped Ba 0.6 Bi 0.4 F 2.4 and its heterostructured Ca 0.6 Bi 0.4 F 2.4 upconversion luminescent materials. The study involves measuring room temperature fluorescence spectra, fluorescence lifetime, and quantum yield, demonstrating the exceptional luminescence performance of Ca 0.6 Bi 0.4 F 2.4 :Yb3+/Er3+. More importantly, we successfully obtained transparent lanthanide-doped Ca 0.6 Bi 0.4 F 2.4 thermoplastic polyurethane (TPU) luminescent films and upconversion luminescent inks. This work highlights the great potential of upconversion nanomaterials in anti-counterfeiting fields. • The Ba 0.6 Bi 0.4 F 2.4 :Yb3+/Er3+ and its heterostructured Ca 0.6 Bi 0.4 F 2.4 :Yb3+/Er3+ upconversion luminescent materials were synthesized by solvothermal method. • The luminescence intensity is Ca 0.6 Bi 0.4 F 2.4 :Yb3+/Er3+ > Ba 0.6 Bi 0.4 F 2.4 :Yb3+/Er3+. • We have produced TPU luminescent films and a green fluorescent ink of Ca 0.6 Bi 0.4 F 2.4 :Yb3+/Er3+. [ABSTRACT FROM AUTHOR]

This work explores a novel ceramic glaze formulation, which incorporates unique anti-counterfeiting features and demonstrates versatile luminescence characteristics that vary with time and excitation conditions. Departing from conventional fluorescent materials employed in anti-counterfeiting measures, the phosphors utilized in this investigation showcase a remarkable ability to emit multiple colors under diverse excitation wavelengths, offering enhanced security and complexity. The key components of the multimode fluorescent glazes are three primary color phosphors: red phosphor (Y 2 O 3 : 0.05Eu3+), green phosphor (SrAl 2 O 4 : 0.01Eu2+, 0.02Dy3+), and blue phosphor (CaAl 2 O 4 : 0.012Eu2+, 0.06Nd3+, 0.036Gd3+). Employing the high-temperature solid-state approach, the synthesis of these luminescent materials was successfully achieved. The phosphors, glazes, and xanthan gum were mixed and ground together. The multimode ceramic fluorescent glazes were obtained by adjusting the ratios of red (R), green (G), and blue (B) phosphors, adding the mixed powders into n-butanol, thoroughly mixing them, and then applying the glazes onto skeleton boards. The glazes were then placed in muffle furnaces at high temperatures after static drying to achieve the desired multimode ceramic fluorescent glazes. This simple process results in low production costs, making it feasible to produce advanced anti-counterfeiting fluorescent glazes at a low cost. The glaze paste was applied to the ceramic sheet using a skeleton plate and watercolor chalk, and an anti-counterfeiting logo in the form of a "butterfly" was created. The logo exhibited dynamic luminescence, with the luminescent effect varying depending on the excitation wavelength and duration. The anti-counterfeiting effect of the pattern demonstrates the promising potential for further development and practical application of the multimode fluorescent glaze. [Display omitted] • Multi-mode luminescent ceramic glaze was synthesized. • The luminescent ceramic glaze exhibited dynamic luminescence. • The luminescent signals are dependent on the excitation wavelength and duration. • This work paves a novel way for ceramic glaze. [ABSTRACT FROM AUTHOR]

Gd3+ co-doping is effective to enhance the photoluminescence of rare earth activators in various host due to energy transfer, however, it is rarely reported via such strategy to regulate persistent luminescence properties. In this work, Gd3+ was co-doped into the SrLaAlO 4 : Tb persistent luminescence phosphors, and it is found that the photoluminescence and persistent luminescence of the products can be simultaneously improved. The results indicate that as the doping concentration of Gd3+ increases, the particle diameters increase which contributes the increased luminescence. Additionally, an energy transfer process from Gd3+ to Tb3+ ions was observed, which enhances the emission of Tb3+ ions. Furthermore, the persistent luminescence properties of the synthesized phosphors were improved. When the UV light source is turned off, the persistent luminescence of SrLaAlO 4 : 0.03Tb3+, x Gd3+ (x = 0.00–0.97) can last for more than 2 h, which is 100 % enhanced compared to SrLaAlO 4 : 0.03Tb3+. The trap distribution of SrLaAlO 4 : 0.03Tb3+, x Gd3+ (x = 0.00–0.97) phosphors was analyzed by thermoluminescence. It is found that after the substitution of La3+ with Gd3+, the trap position shifted towards higher temperatures and the trap concentration increased. The initial intensity of the persistent luminescence was also enhanced after Gd3+ co-doping. Based on the experimental findings, the luminescence and persistent luminescence mechanism of SrLaAlO 4 : 0.03Tb3+, x Gd3+ (x = 0.00–0.97) phosphors were described and discussed. • The photoluminescence and persistent luminescence were simultaneously enhanced via Gd3+ doping. • The trap depth was effectively regulated via Gd3+ doping. • The persistent luminescence of SrLaAlO 4 : Tb, Gd is twice longer than that of SrLaAlO 4 : Tb. [ABSTRACT FROM AUTHOR]

Single doped Mg 0.388 Al 2 O 3.408 O 4 phosphor was prepared and multivalent Mn ion (Mn2+ and Mn4+) emission was achieved in a single host. The structure, morphology, and luminescence characteristics of Mn ions in Mg 0.388 Al 2 O 3.408 O 4 were discussed in detail, especially the temperature dependent emission characteristics of Mn ions. Based on the fluorescence intensity ratio (FIR) of Mn2+ versus Mn4+ and the decay lifetime of Mn4+ emission as the temperature readout, a dual-mode optical temperature-sensing mechanism was proposed and studied in the temperature range of 293–473 K. The maximum relative sensitivities (S r) are derived as 2.83 % K−1 (at 373 K based on FIR) and 3.40 % K−1 (at 473 K based on decay lifetime), respectively. The temperature sensing characteristics of Mg 0.388 Al 2.408 O 4 : Mn2+/Mn4+ powders in a full fiber system were studied, which can provide thermal-sensitive emissions at dual-wavelengths for stable ratiometric temperature sensing with good precision and repeatability. The constructed all fiber temperature sensing system has been applied in the on-line monitoring of CPU temperature. • Emission of multivalent Mn ions (Mn2+ and Mn4+) phosphor in Mg 0.388 Al 2 O 3.408 O 4 host. • A dual-mode optical temperature sensing based on FIR and the decay lifetime as the temperature readout. • Optical thermometry with high relative sensitivity based on FIR (2.83 % K−1) and decay lifetime (3.40 % K−1). • The constructed all fiber temperature sensing system for the on-line monitoring of CPU temperature. [ABSTRACT FROM AUTHOR]

The two-dimensional organic-inorganic hybrid perovskites demonstrate significant potential for use in photodetectors and white light-emitting diodes. In this study, we successfully synthesized pure and Mn2+-doped (PEA) 2 PbBr 4 perovskite via rapid crystallization. The morphology, structure, magnetic properties, and optical characteristics of them were comprehensively characterized. The unusual behavior of free exciton emission is mainly attributed to electron-phonon coupling and negative thermal quenching effects. The self-trapped exciton emission results from self-trapped excited states and electron-phonon coupling. Moreover, energy transfer phenomena are observed between free exciton emission, self-trapped exciton emission, and Mn2+ emission. These findings offer valuable insights into the luminescence mechanism of two-dimensional layered perovskites. [Display omitted] • The pure and Mn: (PEA) 2 PbBr 4 perovskites were synthesized at room temperature. • The free exciton emission exhibits abnormal behavior depending on temperature. • The Mn emission has a weak temperature dependence. • The self-trapped exciton emission becomes visible at low temperatures. • There is energy transfer between free exciton emission, self-trapped exciton emission, and Mn emission. [ABSTRACT FROM AUTHOR]

Solar spectral conversion by a low-cost luminescent coating for greenhouse applications increases crop yield and can contribute to addressing the food crisis. A luminescent coating based on cheap SiO 2 particles doped with Eu2+ and Al3+ demonstrated extra photosynthetic active radiation (PAR) in this work. To optimize the efficiency of this phosphor for greenhouse applications, three phosphor series with varying Al/Eu content in SiO 2 were synthesized via a sol–gel approach and characterized by luminescence decay time, absorption, luminescent excitation, emission, and quantum yield measurements. With increasing the Eu%, at a fixed Al%, the decay time and quantum yield decreased while the emission shifted to the red. The effect can be explained by a more and more efficient resonance energy transfer to lower energy Eu2+ ions and quenching sites. While increasing the Al% at a fixed Eu%, the decay time and quantum yield increased, and the red-shift was reduced. Both effects can be explained by an enhanced Eu2+ solubility (reduced Eu clustering) through the Al3+ co-doping, causing the average Eu2+-Eu2+ distance to be longer and the onset of concentration quenching to shift to a higher Eu%. Specifically, we found that for 1 mol% Eu2+, a minimum of 4 mol% Al3+ was required to avoid concentration quenching. Two indicators were developed to quantify the UV to PAR converting efficiency and to quantify the PAR transmission enhancement. Both indicators were determined in a real coating sample based on the optimized phosphor. The result showed an additional PAR was provided by our luminescent coating. A general discussion about all factors that can bring the conversion efficiency of a phosphor coating closer to the theoretical maximum will be presented. • 4:1 molar ratio of Al:Eu in SiO 2 prevents concentration quenching. • SiO 2 :Al,Eu phosphor achieves the highest quantum efficiency of 74%. • Resonance energy transfer causes the drop of QE and the red shift of emission. • A PAR enhancement metric developed to evaluate greenhouse coatings. • SiO 2 :Al,Eu coating raises 0.34% extra PAR, boosting potentially 0.34% crop yield. [ABSTRACT FROM AUTHOR]

As a new display mode, laser display is becoming popular in the industry, and it has served our lives. In addition, a new material, perovskite quantum dots(QDs) is more capable of energizing laser displays with a narrow half-peak width, tunable emission and high color purity. Here, by incorporating perovskite CsPb(Br x I 1-x) 3 quantum dots into the glass, we explored the performance of large-size glass in laser display. It is demonstrated that the sheet of CsPbBr 3 and CsPb(Br 0.25 I 0.75) 3 glasses has good wavelength uniformity, and the phosphor wheel with the sheets yields a wide color gamut (its color gamut reaches 124.3 % of NTSC and 91.3 % of Rec.2020), which will play a significant advantage in the field of laser projection. • Large-size green CsPbBr 3 and red CsPb(Br 0.25 I 0.75) 3 QDs embedded glasses were successfully prepared. • The optical uniformity of the QDs glass exhibit extremely high luminescence wavelength consistency. • The phosphor wheel yields a wide color gamut with 124.3 % of NTSC and 91.3 % of Rec.2020. • We demonstrate that this material can be used for laser display application. [ABSTRACT FROM AUTHOR]

We report on the crystal growth, polarized spectroscopy, and laser operation of monoclinic Tm3+, Na+(Li+) codoped zinc monotungstate (ZnWO 4) crystals. The Li+ codoping with an optimized Tm/Li ratio enables almost complete local charge compensation leading to better crystal quality, higher Tm segregation coefficient, and longer luminescence lifetime and ultimately the demonstration of laser operation. The modified Judd-Ofelt theory was employed to calculate the Tm3+ transition probabilities yielding a radiative lifetime of the 3F 4 state of 2.59 ms. The corresponding intensity parameters are Ω 2 = 5.194, Ω 4 = 0.658, Ω 6 = 0.471 [10−20 cm2] and α = 0.110 [10−4 cm]. Tm,Li:ZnWO 4 features strongly polarized emission spectra extending beyond 2 μm owing to a large total Stark splitting of the ground-state, Δ E (3H 6) = 644 cm−1. The stimulated-emission cross-section in this spectral range reaches 0.47 × 10−20 cm2 at 2015 nm for light polarization E || N p. The continuous-wave Tm,Li:ZnWO 4 laser generated 282 mW at 1.98 μm with a slope efficiency of 14.7 %, and laser emission at 2.03 μm was also achieved. • Czochralski growth of monoclinic Tm3+, Na+(Li+) codoped zinc monotungstate (ZnWO 4). • Li + codoping provides higher Tm3+ segregation and longer luminescence lifetime. • Tm,Li:ZnWO 4 features strongly polarized emission spectra extending beyond 2 μm. • The stimulated-emission cross-section is 0.47 × 10−20 cm2 at 2015 nm. • First continuous-wave laser operation of Tm,Li:ZnWO 4 crystal at 2 μm is demonstrated. [ABSTRACT FROM AUTHOR]

In this study, a series of Eu3+ doped novel Gd 7 O 6 (BO 3) (PO 4) 2 phosphors has been successful created using a high-temperature solid-state method. The crystal structure, morphology and luminescence properties were under investigation. The samples were tested for photoluminescence (PL) spectra, and the results indicated that the Gd 7 O 6 (BO 3) (PO 4) 2 : Eu3+ phosphors emitted strong reddish-orange light upon excitation at 393 nm. Meanwhile, the strongest peak of the emission peak was located at 614 nm, signifying that the optimal doping concentration of Eu3+ is x = 1.4. The quantum yield of Gd 7 O 6 (BO 3) (PO 4) 2 : 1.4Eu3+ is measured to be 26.26 %. In addition, at 423 K, the luminous intensity of Gd 7 O 6 (BO 3) (PO 4) 2 : 1.4Eu3+ under 393 nm excitation is 85 % of its strength at 298 K, indicating excellent thermal stability. Lastly, a white light-emitting diode (WLED) device was successfully fabricated, boasting a correlated color temperature (CCT) of 3374 K and a Ra value of 86.7. The results suggest that the prepared phosphor, in conjunction with a near-ultraviolet (NUV) light-emitting diode (LED) chip, it holds significant potential for utilization in white light-emitting diodes (WLEDs). • GBPO: 1.4Eu3+ phosphors were firstly synthesized via a high-temperature solid-state. • GBPO: 1.4Eu3+ phosphor can be excited 393 nm, and emit reddish-orange light and exhibits good thermal stability (85%@423 K). • The fabricated WLEDs using the phosphor show excellent performance. [ABSTRACT FROM AUTHOR]

The luminescence stability of carbon quantum dots (CQDs) in air impedes their extensive applications. Ample –NH 2 groups on the surface of a green carbon quantum dots (GCQDs) had high organic reactivity, the surface of GCQDs was modified with allyl functional groups through a simple surface substitution reaction (named as GCQD-A). The surface of the GCQD-A was continuously formed a thin organic shell by free radical copolymerization reaction with methyl methacrylate and styrene respectively, and they were named as GCQD@PMMA and GCQD@PS respectively. The allyl functional groups on the surface of GCQD-A, the shell composition of GCQD@PMMA and GCQD@PS were characterized by their 1H nuclear magnetic resonance (1H NMR) data and infrared adsorption spectra. The luminescence stabilities for GCQD@PMMA and GCQD@PS in air were greatly improved compared with that for the GCQDs. The work can provide a novel method to get stable luminescence of CQDs in air, and it will extend their application areas in solid state. The luminescence stabilities in air for GCQDs were greatly enhanced by coating a very thin organic polymer shells on the surfaces of GCQDs. [Display omitted] • The luminescence stability of GCQDs in air was greatly enhanced. • Very thin organic polymer shells were successfully coted on the surfaces of GCQDs. • A new method to protect the surface excited states of carbon quantum dots. [ABSTRACT FROM AUTHOR]

Trivalent-doped tetragonal xenotime yttrium orthophosphate phosphors have attracted significant attention as promising materials for deep ultraviolet (DUV) luminescence. In this study, we achieved DUV electroluminescence (EL) using Bi3+-doped bi-phase yttrium phosphate (YPB) phosphor under an AC-driven sinusoidal waveform. Phosphor powder was synthesized via a solid-state reaction with an optimal Bi3+ concentration. The phosphor exhibited a mixed phase of xenotime tetragonal YPO 4 and monoclinic Y(PO 3). We suggest that the mixed phase within the phosphor particles plays a crucial role in enhancing light generation via a bipolar field emission mechanism in the developed powder-based EL device. It emitted a narrow-band DUV emission spectrum peaking at 243 nm, which was attributed to the 3P 1 → 1S 0 transition of the Bi3+ ions within the mixed host lattices. Moreover, it has a lower voltage application than the excimer lamp DUV sources. The application of the YPB phosphor in EL devices presents an appealing outlook for future advancements in the development of DUV sources. • Deep-ultraviolet electroluminescent (DUV-EL) device is presented utilizing Bi3+-doped yttrium phosphate (YPB) phosphor. • The optimum dopant concentration, phase-morphological, and electro-optical properties are investigated. • Under AC-driven sinusoidal waveform, the EL emits a narrowband DUV spectrum peaking at 243 nm. [ABSTRACT FROM AUTHOR]

The possibility of YAG:Ce3+ coatings phosphor formation by reactive magnetron deposition during sputtering of metal targets in an atmosphere of argon and oxygen activated by a radio-frequency source of inductively coupled plasma has been studied. The installation consists of three middle-frequency magnetrons with Y, Al and Ce targets with power of 1000, 1570 and 150 W, respectively. The (Y–Al–O):Ce coatings were deposited in metal and oxide sputtering modes of yttrium and aluminium targets. The coating deposition rate on the planetary rotating substrates in the metallic sputtering mode reaches of 0.67 nm/s. This is about an order of magnitude higher compared to the oxide sputtering mode and the method of radio-frequency magnetron sputtering of ceramic targets commonly used to deposit such coatings. Characterization of the elemental and phase composition of the coatings showed the YAG:Ce crystal structure formation during annealing both in air at 1100 °C and in a nitrogen atmosphere at 1200 °C. Cathodo- and photoluminescent spectroscopy was used for study of YAG:Ce thin films emission properties. The emission properties of YAG:Ce correspond to the radiation transition in Ce3+ ions. It was found that the intensity of both types of luminescence turned out to be slightly higher for samples annealed in air. It enhanced with increasing coating thickness in the considered range from 1.8 to 7.0 μm. The suggested approach could be potentially used for luminescent coatings formation with high level of the emission properties. • The rate of (Y–Al–O):Ce deposition in the metallic mode of MF magnetron sputtering is 20 times higher than in the oxide one. • MF magnetron sputtering in metallic mode and subsequent annealing at 1100 °C create YAG: Ce phosphor. • Luminescence intensity of the YAG:Ce coatings the higher, the greater their thickness and crystallites size. [ABSTRACT FROM AUTHOR]

This study extensively analyzes the concentration effect of cadmium in the chosen Barium boro-phosphate glass host for the fabrication of optoelectronic devices. The impact of substitution of Zn2+ ions with Cd2+ ions on the luminescent features of Eu3+ ions in the glass host was analyzed using NIR-Vis-UV absorption, luminescence, and fluorescence decay spectrum probes along with the Judd-Ofelt analysis at ambient temperature. Nephelauxetic and bonding parameters (β and δ) were evaluated through the reported relations, and it suggests that the present host glass offers ionic bonding with the doped Eu3+ ions. The pure Zn2+ and Cd2+ contained glasses exhibit stronger ionic bonds with the doped Eu3+ ions. The Judd-Ofelt model of investigation is used to estimate the radiative and further lasing properties of every emission found in the glasses that were created, and the outcomes were contrasted with the pertinent literature. The estimated phonon energy of the present glasses is found to be 753 cm−1. The increase in concentration of Cd2+ ions increases the fluorescence intensity. Using the CIE 1931 model, the color chromaticity parameters and correlated color temperature (CCT) were derived from the fluorescence spectra. It was found that the CCT values are between 1650 and 1925 K. The luminescence decay reveals the lack of non-radiative phonon-assisted transition in the produced glasses, which fits the single exponential decay model rather well. All the parameters, such as experimental lifetime and quantum efficiency (38.6 %) appropriate to the BPBZC 10 :Eu glass, suggest its potential utilization as a laser gain medium and related optoelectronic applications. • Presiding of higher amount of Cd2+ cations increase the asymmetry aroundthe Eu3+ ions ligand sites. • Quantum efficiency of Eu3+ ions in the present host is 38.6 %. • Color the purity of the red emission is 68 %. • The glass with equal proportion of Zn2+ and Cd2+ exhibits a weaker ionic-bond in Eu−O linkages. [ABSTRACT FROM AUTHOR]

In this study, we examine the impact of optical and scintillation properties on needle-shaped bis(butylammonium) lead bromide [(BA) 2 PbBr 4 ] crystals (average length of 12.7 mm and average width of 1.3 mm), considering different growth methods and dimensions. Needle-shaped crystals with a length-to-width aspect ratio greater than 10 are essential for cutting-edge radiation imaging technology. Through X-ray diffraction characterization, we observe lattice expansion in the needle-shaped crystals compared to previous single crystals. This expansion leads to a stronger overlap between absorption and photoluminescence (PL) spectra, resulting in a smaller Stokes shift of 26 meV. Time-resolved PL analysis reveals a fast decay component of 0.8 ns, which is 68 % faster than the previously reported best value of 2.0 ns, with an average decay time of 3.6 ns, 48 % faster than the best reported value of 7.0 ns. Although our measured sample exhibits a comparatively low light yield (LY) of 7.8 ph/keV due to strong self-absorption, the best energy resolution is observed with a value of 11.5 %, similar to the best reported value of 10.9 %. Despite this, the LY is notably superior to that of previously reported benzylammonium lead bromide [(BZA) 2 PbBr 4 ] crystals (3.7 ph/keV). Additionally, scintillation decay shows a fast component of 9.4 ns and an average decay time of 119 ns. These characteristics make two-dimensional-(BA) 2 PbBr 4 needle-shaped crystals promising candidates for cost-effective and scalable applications in radiation imaging technology. • Solution process 2D-(BA) 2 PbBr 4 needle-shaped crystals was successfully synthesized with an aspect ratio of length to width exceeding 10. • Time-resolved photoluminescence analysis reveals ultra-fast decay component of 0.8 ns, which is 68 % faster than the reported value of 2.0 ns. • Solution grown needle-shaped 2D perovskites are an interesting and versatile class of materials for cost-effective and scalable in cutting-edge radiation imaging technology. [ABSTRACT FROM AUTHOR]

The development of dynamic multi-color luminescence is a tremendous challenge for anti-counterfeiting. Herein, we have successfully synthesized Cr3+ activated gallium-silicate base material systems as the effective luminescent materials responsive to multiple field stimulation, exhibiting sextuplet luminescence including photoluminescence, strong red persistent luminescence (PersL), photo/thermo stimulated luminescence (PSL/TSL), photo-stimulated PersL and up-conversion luminescence (UCL). The luminescence quenching temperature is also improved in Cr3+,Yb3+,Er3+ co-doping sample relatives to Cr3+ single-doping phosphor. Especially, when Er3+ and Yb3+ are co-doped into Cr3+ activated phosphor system, UV preirradiated phosphor not only demonstrates an additional UCL from Er3+ ions accompanied with red PSL from the Cr3+ under NIR laser irradiation, but also leads to a dynamic change in color/brightness under the extension of NIR laser irradiation time. The multimode luminescence mechanisms are also proposed. Based on excellent luminescence characteristics, multi-color and multi-mode anti-counterfeiting patterns have been designed, especially appearing of dynamic anti-counterfeiting on luminescent color/brightness, which provides new dimensions for anti-counterfeiting technologies. • ZGGSO:Cr,Yb,Er phosphor demonstrates new UCL modes and enhanced red PersL. • Luminescence quenching temperature is improved in Cr3+,Yb3+,Er3+ co-doped sample relative to Cr3+ single-doped phosphor. • Quintuplets-mode luminescence including PL, red PersL, PSL/TSL, PSPL and UCL can be detected. • A PersL enhancement mechanism of Cr3+ is proposed based on the formation of electron-hole pair traps. [ABSTRACT FROM AUTHOR]

Water-dispersed red upconversion nanoparticles (UCNPs) have great application prospects in the biomedical field. Thus, a series of Er3+-based upconversion nanoparticles (Er-UCNPs) with excellent red upconversion luminescence under three-wavelength NIR excitation (808/980/1550 nm) were prepared by a simple thermal decomposition method, and then further functionalized by PAA to achieve good water dispersibility. Compared with NaErF 4 bare core, the emission intensity of Er-UCNPs samples doping of 0.5%Tm3+ and 0.5%Ho3+ as energy capture centers was significantly enhanced, and further improved after coating with NaYF 4 inert shell. Meanwhile, among all Er-UCNPs@NaYF 4 samples, NaErF 4 @NaYF 4 exhibited the highest emission intensity and longest luminescence lifetime due to the efficient suppression of luminescence quenching effect, while NaErF 4 :0.5%Tm3+@NaYF 4 showed highest red luminescence purity owing to the energy transfer process between Tm3+(3H 5) and Er3+(4I 13/2). The hydrophilic Er-UCNPs@NaYF 4 @PAA samples still maintained good red luminescence under multi-wavelength excitation. The luminescence enhancement mechanism in Er-UCNPs@NaYF 4 was discussed in detail based on spectral characteristics. The as-prepared water-dispersed Er-UCNPs@NaYF 4 @PAA with bright red luminescence under multi-wavelength NIR excitation will have potential applications in targeted therapy and deep tissue imaging. • All Er-UCNPs@NaYF 4 nanorods exhibits excellent red luminescence under multi-wavelength excitation at 808/980/1550 nm. • Doping Tm3+/Ho3+ ions into Er-UCNPs as energy capture centers can improve red luminescence intensity. • The luminescence quenching effect can be effectively inhibited by coating NaYF 4 shell on Er-UCNPs surface. • The highest R/G value is obtained in the NaErF 4 :0.5%Tm3+@NaYF 4. • Water-dispersed Er-UCNPs@NaYF 4 @PAA sample maintains good red emission. [ABSTRACT FROM AUTHOR]

KSrGd(PO 4) 2 :Ln3+ (Ln = Ce, Sm, Eu, Tb, Dy, Dy/Eu, Yb/Ho, Yb/Er, Yb/Tm) phosphors were synthesized by high temperature solid state method. Doping the KSrGd(PO 4) 2 matrix with 5%Dy3+ ions resulted in white light emission under 345 nm excitation. The calculated color temperature (CCT) of this white light is 5523 K, indicating as positive white light. It was found that the luminous intensity of the obtained KSrGd(PO 4) 2 :5%Dy3+ at 200 °C was 76.80 % of that at room temperature, showing good thermal stability as well as possibility of application in white LED. Under the excitation at 392 nm, the fluorescence quantum yield of KSrGd(PO 4) 2 :10%Eu3+ is 79.92 %. Energy transfer between Dy3+ and Eu3+ is observed in KSrGd(PO 4) 2 :Dy3+/Eu3+ samples, with identified mechanism as the quadrupole-quadrupole interaction. Tunable luminescence ranging from white to yellow then to orange-red is achieved by adjusting the doping concentration of Eu3+ in KSrGd(PO 4) 2 :5%Dy3+, x%Eu3+. Under the excitation of 980 nm near-infrared light, the prepared KSrGd(PO 4) 2 :Yb3+/Ho3+, KSrGd(PO 4) 2 :Yb3+/Er3+ and KSrGd(PO 4) 2 :Yb3+/Tm3+ samples showed up-conversion emissions of red, yellow and blue, respectively, with two-photon processes. In KSrGd(PO 4) 2 matrix, multi-color and multi-security marks were successfully prepared by utilizing up/down conversion luminescence characteristics, which obtained good anti-counterfeiting effect and improved anti-counterfeiting security. Therefore, the obtained KSrGd(PO 4) 2 : Ln3+ phosphors exhibit promising application prospects in the fields of WLED and multiple anti-counterfeiting. • The luminous intensity of the obtained KSGP: 5%Dy3+at 200 °C was close to that at room temperature, showing excellent thermal stability. And the activation energy value of KSGP:5%Dy3+ sample is 0.245 eV. • Doping the KSrGd(PO 4) 2 matrix with 5%Dy3+ ions resulted in white light emission under 345 nm excitation, indicating as positive white light. • The obtained KSGP:10%Eu3+ red phosphor exhibits a fluorescence quantum yield as high as 79.92 %. • The photoluminescent multi-color anti-counterfeiting materials with high security were prepared by using the polychromatic luminescence characteristics of the synthesized KSGP: Ln3+ phosphors. [ABSTRACT FROM AUTHOR]

Advanced optical materials inspired by natural minerals and non-toxic light elements, such as the Hackmanites (Na 8 Al 6 Si 6 O 24 (Cl,S) 2), find vast possibilities of applications as they can simultaneously perform photochromism and persistent luminescence (PersL). In this work, we have explored a rapid and energy-efficient microwave-assisted (MASS) methodology for the synthesis of PersL and photochromic hackmanites. In addition, we have prepared hackmanite materials using a zeolite-free precursor to control the Na–Al–Si ratio and study its influence on the materials photoluminescent properties. The PersL hackmanites showed a white-bluish emission color, with up to 2 h of emission time. Zeolite-free photochromic materials were able to change the color from white to purple/blue efficiently with a few seconds of 254 nm excitation, but the usage of zeolite precursors enhanced the overall optical performance. Microwave synthesis times of 10–40 min were demonstrated to be optimal, as longer times boosted the formation of nepheline spurious phase, which decreases luminescence efficiency. In this way, the MASS method led to a reduction of reaction time up to 98 %, yielding hackmanite materials with similar photoluminescent or photochromic properties compared to those obtained by a 24 h conventional solid-state synthesis. This work represents a significant improvement toward coupling eco-friendly synthetic processes to eco-friendly solid-state materials for PersL illumination and PersL/photochromism optical marking. • New synthesis approaches for Persistent Luminescent and Photochromic Hackmamnite based materials. • Microwave-assisted solid-state method (MASS) saves up to 98 % of time for Hackmanite synthesis. • Zeolite-free synthesis opens possibilities to explore the Na–Al–Si ratio and its influence on hackmanite properties. [ABSTRACT FROM AUTHOR]

High quality Li 2 B 4 O 7 :Mn,Eu glasses containing 1.0 mol.% MnO 2 and Eu 2 O 3 were prepared and investigated by XRD, EPR and optical spectroscopy techniques. Obtained data analysis shows that Mn is incorporated into the glass network as Mn2+ and Mn3+. Parameters of observed Mn2+ EPR signals in the Li 2 B 4 O 7 :Mn,Eu glasses were determined. Optical absorption spectrum of the studied glasses consists of broad band at 464 nm corresponding to the 5E g (D) → 5T 2g (D) transition of Mn3+ (3 d 4) ions and few narrow weak bands of the Eu3+ (4 f 6) ions. Emission spectra of the Li 2 B 4 O 7 :Mn,Eu glasses in orange-red region exhibit several sharp bands corresponding to the 5D 0 → 7F J (J = 0–4) transitions of Eu3+ ions and broad band belonging to the 4T 1g (G) → 6A 1g (S) transition of Mn2+ (3 d 5) ions. Comparative discussions were made on the luminescence spectra and decay curves of Mn2+ and Eu3+ ions in the Li 2 B 4 O 7 :Mn,Eu glasses and those in Mn-doped and Eu-doped glasses with the Li 2 B 4 O 7 basic composition. [Display omitted] • Glasses with the Li 2 B 4 O 7 :Mn,Eu composition of high optical quality was obtained. • XRD, EPR, UV–Vis absorption, and photoluminescence of Li 2 B 4 O 7 :Mn,Eu glasses are studied. • All Mn2+ EPR spectra in Li 2 B 4 O 7 :Mn,Eu glasses are interpreted and their parameters are defined. • Optical absorption bands observed in the Li 2 B 4 O 7 :Mn,Eu glasses are identified and analysed. • Eu3+ and Mn2+ luminescence spectra and decay kinetics in Li 2 B 4 O 7 :Mn,Eu glasses are studied. • Energy transfer channels Eu3+↔Mn2+, Eu3+.→Mn3+, Mn2+→Mn3+ in studied glass are discussed. [ABSTRACT FROM AUTHOR]

We report on the luminescence properties of hydrothermally synthesized BaLuF 5 :Pr3+(1%) nanoparticles having a cubic crystal structure. The properties were investigated at low temperatures using time-integrated and time-resolved luminescence spectroscopy under VUV photon excitation in the energy range of 5–45 eV. This spectral region covers both the Pr3+ 4f2→4f15d1 transitions and the intrinsic absorption of the host material. Due to the weak crystal field, only the intra-configurational Pr3+ 4f2→4f2 transitions were observed, resulting in photon cascade emissions. According to structural and morphological studies, the nanoparticles, with an average size of 21 ± 4 nm, were found to possess large amounts of defects, which are further confirmed through luminescence spectroscopy. The influence of non-radiative decay at the surface and energy transfer to the defects are responsible for the shortening of luminescence decay detected for the 1S 0 transitions of Pr3+ ions and intrinsic UV cross-luminescence of host materials. We have discussed the specific energy transfer processes that populate various luminescence centers and evaluated BaLuF 5 :Pr3+(1%) nanoparticles for potential optical applications. • "Investigated luminescence properties of hydrothermally synthesized BaLuF5+:Pr3+(1 %) nanoparticles under VUV excitation". • "Photon cascade emission observed due to the 4f21S 0 level being below the 4f15d1 states". • "Structural and morphological studies reveal a significant amount of defects in nanoparticles". • "Non-radiative decay at surfaces and energy transfer to defects shorten luminescence decay times". • "Potential optical applications in fast timing due to ultrafast cross-luminescence and 1S 0 transitions of Pr3+ ions". [ABSTRACT FROM AUTHOR]

Herein, ZMGGO:Cr3+ nanoparticles were prepared by incorporating Mg2+ ions into Cr3+-doped zinc gallogermenate nanoparticles through a hydrothermal path in combination with a vacuum heating. The average size of ZMGGO:Cr3+ nanoparticles minishes from 59 to 12 nm with growing Mg2+ concentration. Meanwhile their luminescence intensity at 696 nm of ZMGGO:Cr3+ nanoparticles was only decreased by less than half of that of the undoped nanoparticles due to the decreased particle size after Mg doping. Meanwhile, the integral luminescence intensity of their entire emission band shows an increasing trend with increasing temperature due to the enhanced phonon sideband luminescence at high temperature. More important, it is found that the formation energies associated with Mg′ Ga -Gao Zn and Zn′ Ga -Gao Zn defects are −1.2 and 1.69 eV, respectively, suggesting the enhanced afterglow intensity of ZMGGO:Cr3+ can be ascribed to Mg doping leading to the increased number of these anti-site traps. Finally, the dual-level time-gate optical encryption was demonstrated using phosphorescent inks containing ZMGGO:Cr3+ nanoparticles with different afterglow intensities. • Mg2+ and Cr3+ codoped zinc gallogermanate (ZMGGO:Cr3+) nanoparticles were prepared. • Their average size decreases from 59 to 12 nm with increasing Mg concentration. • The presence of new anti-site traps improves their afterglow intensity. • The dual-level time-gate encryption was demonstrated using different afterglow inks. [ABSTRACT FROM AUTHOR]

Gd 2 O 2 S:Pr,Ce nanophosphors have been prepared by liquid-phase method using NH 2 SO 3 H as the sulfur source for the first time. The formula of the novel precursor was determined as Gd 2 (OH) x (NH 2 SO 3) 6-x ∙nH 2 O by EDS, TG-DSC and FT-IR spectroscopy, and the precursor exhibited an amorphous structure and lamellar morphology as deduced from XRD and SEM. The optimum pH was 8 and the optimum calcination temperature was 1000 °C for the preparation of Gd 2 O 2 S:Pr,Ce from the precursor. The PL quantum yield and the fluorescence lifetime of Gd 2 O 2 S:Pr,Ce powder was 53.62 % and 2.48 μs respectively, which will allow the preparation of ceramic scintillators with high optical output and energy resolution. Compared to the traditional sulfur sources such as sublimed sulfur, and H 2 SO 4 , NH 2 SO 3 H is harmless and avoids pollution gases during the preparation of Gd 2 O 2 S:Pr,Ce nanophosphors. It also eliminates the need to add additional reagents, simplifying the preparation steps and reducing production costs. • GOS powder was synthesized by using a new sulfur source NH 2 SO 3 H for the first time. • The novel precursor Gd 2 (OH) x (NH 2 SO 3) 6-x ∙nH 2 O was analyzed in detail. • GOS powder was with high PL quantum yield and short fluorescence lifetime. [ABSTRACT FROM AUTHOR]

Sm-doped CaCl 2 , SrCl 2 , and BaCl 2 bulk crystals were synthesized using the conventional vertical Bridgman method, and the photoluminescence, radioluminescence, and detector properties were evaluated. The Sm-doped CaCl 2 , SrCl 2 , and BaCl 2 samples show a broad emission band at 750, 690, and 650 nm, respectively, which is attributable to the 5d-4f transitions of Sm2+. The pulse height spectra under 137Cs γ-rays (662 keV) show that the Sm-doped CaCl 2 and SrCl 2 exhibit 9300 and 33000 photons/MeV, respectively. These samples can be used for γ-ray measurements in the red to NIR region. • Sm-doped CaCl 2 , SrCl 2 , and BaCl 2 crystals were synthesized using the conventional vertical Bridgman method. • The photoluminescence, radioluminescence, and detector properties were evaluated. • The samples show a broad emission band at 600–800 nm due to Sm2+. • Sm-doped CaCl 2 , SrCl 2 , and BaCl 2 exhibit light yield of 9300, 33000, and 16000 photons/MeV, respectively. [ABSTRACT FROM AUTHOR]

In practical applications involving high temperatures in oxides and oxide-based structures, challenges such as flames and aggressive environments are common. Turbine engines, where oxide coatings are crucial, face difficulties in temperature measurement due to rapid part motion. The emergence of luminescence thermometry offers advantages in such scenarios and has been studied extensively. However, thermal quenching (TQ) of luminescence happening at such conditions limits the use of phosphor materials as luminescence thermometers for high-temperature sensing, thereby restricting the achievement of sufficient sensitivities and temperature resolutions. Thus, thermally stable phosphors, or more favorably phosphors with anti-TQ of luminescence, have been explored to address TQ issues of luminescence thermometry in recent years. Particularly, phosphors based on negative thermal expansion (NTE) as host matrices have shown feasibility in luminescence thermometry at temperatures exceeding 600 °C. This review focuses on NTE-based phosphors, addressing their luminescent properties and analytical techniques for extending the temperature measurement range. The aim of this review is for better understanding of the structural changes with temperature of NTE-based phosphors, assessing their potential for temperature sensing in harsh conditions, and ultimately encouraging researchers to explore new NTE-based phosphors. The article comprehensively reviews luminescence thermometry using negative thermal expansion (NTE) host matrices. It highlights the challenges of thermal quenching in traditional luminescence thermometry at high temperatures and discusses the advantages of using NTE materials to address these challenges. The review covers principles, applications, and advancements in the field, emphasizing NTE-based phosphors for high-temperature sensing and their potential for improving temperature measurement accuracy in harsh conditions. It discusses individual NTE materials and composite phosphors composed of NTE and positive thermal expansion hosts, showcasing their performance in temperature sensing through detailed examples and research findings. [Display omitted] • Summarizes significant advancements in thermometric temperature measurement techniques. • Showcases NTE host materials for luminescence thermometry. • Reviews the impact of NTE properties on the thermal quenching process. • Contributes to the fundamental understanding of NTE materials in optical thermometry. • Opens new pathways for developing efficient temperature sensors for industrial applications. [ABSTRACT FROM AUTHOR]

Near-infrared (NIR) phosphor-converted light-emitting diode (pc-LED) has been considered as a smart light source for NIR spectroscopy applications, leading to a growing need of developing broadband NIR phosphors. Herein, a new composition Zn 4 InSbO 8 :Cr3+ phosphor with classical spinel-type structure was synthesized, which emits a broadband NIR light covering a region of 700–1200 nm with a peak centered at 860 nm under 460 nm excitation. The sample with an optimized Cr3+ concentration possesses a full width at half maximum (FWHM) as broad as 180 nm mainly ascribing to multi crystallographic sites occupation. Moreover, the absorption efficiency (AE), internal quantum efficiency (IQE) and thermal stability were investigated to estimate the practicality. The relatively long-wavelength NIR emission produced by Cr3+ in this spinel make it suitable for multi-functional applications. Finally, the asprepared phosphor combining with blue LED chip is used to fabricate a prototype NIR pc-LED, giving a NIR output power of 4.8 mW under 100 mA forward bias current with a photoelectric efficiency of 1.63%, showcasing the potential use of this material as a luminescent converter in the application of NIR pc-LEDs. • A spinel-type Zn 4 InSbO 8 :Cr3+ near-infrared phosphor was synthesized. • A broadband NIR emission of this material with peak located at 860 nm can be obtained under 460 nm excitation. • A prototype near-infrared emitting device was achieved, which demonstrates excellent performance in night vision application. [ABSTRACT FROM AUTHOR]

In order to estimate the stability of the light output of the scintillation detector, the Lu 2 SiO 5 :Ce scintillation crystals, additionally doped with Ca2+ ions at concentrations of 0 ÷ 0.4 at%, were studied. The spectra of optical absorption, gamma-luminescence, thermal luminescence, dose and temperature dependences of luminescence were measured. Gamma-luminescence in the dose range 10 - 5·107 Gy was recorded using 60Co gamma-source at the temperature range of 310–460 K. In contrast to the initial sample (non-doped with Ca), in the sample doped with 0.1 at% of Ca, an increase in the luminescence intensity was observed in the range of 390–425 nm, but further with an increase in the concentration of Ca (0.3–0.4 at%), the intensity of this band decreased to the initial level (undoped). At Ca concentrations of 0.3 and 0.4 at%, the intensity of the Ce1 center band remains practically unchanged up to a dose of 5·107 Gy. LSO crystals doped with Ce 0.1 at% and co-doped with Ca 0.1 at% can be recommended as a scintillation detector up to a gamma-dose of 105 Gy at room temperature. • Ca-codoped Lu 2 SiO 5 :Ce crystals are studied as a material for scintillation detector. • At Ca 0.1 at% an increase in the luminescence at 390–425 nm was observed. • At Ca 0.3 at% the Ce1 center emission doesn't change up to a γ-dose of 5·107 Gy. • Defect complexes completely discolor at room temperature in two days. [ABSTRACT FROM AUTHOR]

The emergence of near-infrared (NIR) luminescence from lanthanide (Ln3+) ions doped lead-free Cs 2 AgInCl 6 double perovskites (DPs) has garnered significant attention due to its extensive range of potential applications. Unfortunately, they still suffer from weak NIR emission due to the inherent wide band gap of DPs resulting in inefficient energy transfer from the host to Ln3+. Herein, Bi3+ can act as the sensitizer to activate Ho3+ emission and reduce the excitation energy in Cs 2 AgInCl 6 : Ho. Under 400 nm excitation, Bi3+ co-doped Cs 2 AgInCl 6 : Ho shows 39 times and 21 times higher emission intensity than Cs 2 AgInCl 6 : Ho in Visible and NIR. As a result, a photoluminescence quantum yield of 18.63 % ranging from 800 to 1600 nm can be obtained. Finally, by coupling a Bi-doped sample with a commercial near-ultraviolet LED chip (395 nm), a compact Vis-NIR ultrawideband light source was prepared, which has promising applications in multifunctional illumination and night vision. [Display omitted] • A novel Cs 2 AgInCl 6 : Bi3+, Ho3+ microcrystal material has been successfully synthesized. • Bi3+ was employed to produce new light absorption making it more compatible with NUV commercial chips. • The underlying reasons for the enhanced NIR-PLQY (∼18.63 %) resulting from Bi3+ sensitization have been elucidated. [ABSTRACT FROM AUTHOR]

Oxygen vacancies play an important role in the formation of the electrical and optical properties of hafnium oxide. Both conductivity and emission bands are determined by this intrinsic defect. The work studies the luminescence of oxygen vacancies. The spectral and temperature dependences of luminescence show the leading role of electron-phonon interaction. The work proposes an algorithm for determining the parameters of this interaction and constructs configuration-coordinate diagrams of emission centers that are associated with different charge states of oxygen vacancies in hafnium oxide. • Hafnium oxide luminescence spectra of 1–3 eV range are analyzed. • The bands are caused by transitions between the oxygen vacancy electronic states. • The shape of the emission bands is due to the electron-phonon interaction. • The vacancy content changes under technological operations, bands intensity as well. • So photoluminescence spectra are a useful tool for technological processes control. [ABSTRACT FROM AUTHOR]

Single crystals of Gd 3 (Ga,Al) 5 O 12 :Ce,Mg with different concentration of Mg2+ ions varying from 0 to 0.029 at.% are investigated by the X-ray diffraction, steady-state and time-resolved photoluminescence, and thermally stimulated luminescence (TSL) methods in a wide temperature range (77–510 K). The origin and structure of the luminescence centers are considered. The influence of Mg2+ ions on the structure of the Ce3+-related excited state, the processes taking place in this state, and the TSL characteristics is clarified. At low temperatures, the photoluminescence optical quenching in close {Ce3+ - Mg2+} pairs is found to be responsible for the light yield reduction accompanied with the acceleration of the luminescence decay kinetics. At room temperature, the luminescence quenching can be additionally caused by the thermal ionization of the 5d 1 excited state of Ce3+ ion, whose probability increases with the increasing Ga content. The conclusion is made that in order to create the fast scintillator with the maximum light yield, the concentration of intrinsic crystal lattice defects in Gd 3 (Ga,Al) 5 O 12 :Ce,Mg should be minimized, the optimum composition of the host should be chosen, and the balance between the concentrations of the doped Mg2+ and Ce3+ ions should be optimised. • Photo- and thermoluminescence and XRD of Gd 3 (Ga,Al) 5 O 12 :Ce,Mg crystals are studied. • Influence of Mg2+ ions on the Ce3+-related luminescence and excited states is clarified. • Optical quenching in close {Ce3+ - Mg2+} pairs results in the light yield reduction and accompanied with acceleration of the Ce3+ luminescence decay kinetics. • Ga3+ ions and intrinsic defects strongly influence the luminescence thermal quenching. • Optimum host composition and preferable Ce3+/Mg2+ concentration ratio are considered. [ABSTRACT FROM AUTHOR]

Near-infrared (NIR) phosphor tetragonal K 3 GaF 6 :Cr3+ with the space group of I 4 1 / a is synthesized through the coprecipitation method, which shows a broadband emission from 600 to 950 nm due to the 4T 2 →4A 2 transition at ambient condition. The luminescent properties and phase transition of K 3 GaF 6 :Cr3+ are investigated under different temperatures and pressures using luminescence spectra and Raman spectra. K 3 Ga 0.95 F 6 :0.05Cr3+ undergoes two phase transitions at 170 °C and 230 °C respectively, but Cr3+ exhibits similar broad emission in three different structures. Different from a sequence of phase transitions upon heating, no phase transition is observed up to 22 GPa. However, pressure-induced crossover of the 4T 2 and 2E states presents at 9.3 GPa, resulting in dominant narrow-band emissions from the 2E→4A 2 transition at higher pressure. These results suggest that pressure can regulate the luminescence properties of K 3 GaF 6 :Cr3+ phosphor effectively. This work will deepen the understanding of Cr3+-doped fluoride, which is helpful to expand the application of NIR luminescent materials under extreme conditions. • Tetragonal K 3 GaF 6 :Cr3+ is synthesized through coprecipitation procedures, showing a broadband NIR emissions. • The temperature- and pressure-dependent structure and luminescent properties of tetragonal K 3 GaF 6 :Cr3+ are studied. • Pressure-induced level crossing of 4T 2 and 2E occurs at 9.3 GPa. • This study will promote the potential applications of NIR phosphors under extreme conditions. [ABSTRACT FROM AUTHOR]

In recent years, the fluorescence intensity ratio (FIR)-based technique for optical non-contact temperature measurement is of great interest to researchers due to its promising wide range of applications in high-voltage electricity fields, fires, corrosive environments, biological tissues, as well as other fields. Unfortunately, the FIR techniques based on thermally coupled energy levels (TCLs) often have the problem of low sensitivity as a result of the narrow energy gap. In contrast to FIR techniques with TCLs, the FIR technique with non-thermal coupled energy levels (NTCLs) is no longer restricted by the energy gap and is expected to achieve high signal resolution. In this study, we attempted to acquire a thermometric material that possesses high sensitivity as well as high signal resolution with the help of NTCLs. We successfully prepared NaYbF 4 :Er3+@NaYbF 4 :Tm3+ core-shell microcrystals by solvothermal technique using NaYbF 4 as matrix and Er3+ and Tm3+ as luminescent centers and made necessary investigations on their crystal structures, microscopic morphologies, intrinsic mechanisms, and thermometric properties. The sample phosphors in a 980 nm laser show bright upconversion (UC) luminescence with emission peaks corresponding to the characteristic energy level jumps of Er3+ as well as Tm3+, respectively. The temperature sensing characteristic parameters have been investigated by FIR techniques with TCLs (2H 11/2 → 4I 15/2 (Er3+)/4S 3/2 → 4I 15/2 (Er3+)) & NTCLs (3H 4 →3H 6 (Tm3+)/1G 4 →3H 6 (Tm3+),3H 4 →3H 6 (Tm3+)/2H 11/2 → 4I 15/2 (Er3+),3H 4 →3H 6 (Tm3+)/4S 3/2 → 4I 15/2 (Er3+) and 3H 4 →3H 6 (Tm3+)/4F 9/2 → 4I 15/2 (Er3+)), respectively. It is shown that the maximum absolute & relative sensitivities are 0.5677 K-1(495 K) as well as 1.20 % K−1(445 K) respectively with good thermal stability. In addition, the NTCLs have good separation of the emission bands, which enables the material to have excellent signal discrimination in temperature detection. These results indicate that the material is expected to be a potential candidate for optical thermometers. • The NaYbF 4 :Er3+@NaYbF 4 :Tm3+ phosphors were obtained by the solvothermal technique. • This experiment focuses on the temperature measurement of NTCLs. • Based on the FIR technique, the S a and S r are 0.5677 K-1 and 1.20 %K−1, respectively. • The results show that the phosphor outperforms most materials. [ABSTRACT FROM AUTHOR]

This research investigates the influence of Europium (Eu3+) ions concentrations on the optical, radiation shielding characteristics and photoluminescence (PL) properties of Alkaline Earth Boro Tellurite (AEBT) glasses. Absorption measurements of Eu3+ions doped AEBT glasses were used to determine the bonding parameters between the ligands and the ions. Excitation wavelength (394 nm) was used to record the PL spectra of the as prepared glasses , and analyzed for the dependent radiative characteristics and J-O parameters. The experimental lifetime (τ exp) and radiative lifetimes (τ R) of the as-prepared glass samples were estimated from the PL decay spectral profiles of the 5D 0 level recorded at 613 nm emission under 394 nm excitation, and the quantum efficiency was then calculated. Based on its relatively higher values of the stimulated emission cross-sections and quantum efficiency, as well as its intense red luminescence at 613 nm (5D 0 →7F 2), the 1.0 mol% of Eu3+ ions doped AEBT glass is considered as a good optical material. In addition, the gamma-ray shielding properties have also been investigated at different photon energies ranging from 0.015 to 15 MeV using Phy-X software. From the results it is contemplated that, AEBTEu2.5 glass has the potential with better radiation absorption compared to regular concrete and other glass systems. The as prepared glasses are also suitable for optoelectronic device applications in addition to radiative shielding applications. • The CIE chromaticity coordinates of the titled glasses falls in the red region of the visible spectrum. • The 1.0 mol % of Eu3+ ions doped AEBT glass suitable for intense visible red emitting optoelectronic devices. • AEBTEu1.0 glass has high stimulated emission cross-section and branching ratios. • Prepared glass samples absorb radiation better than concrete and other glass systems. • AEBTEu2.0 glass is suggested for shielding applications. [ABSTRACT FROM AUTHOR]

Mg2+'s effect on Ca(WO 4): Tm3+/Yb3+ photoluminescence was examined. A possible electronic device application has drawn attention to the Ca(WO 4) phosphor doped with Tm3+/Yb3+/Mg2+ ions. This work used high-temperature solid-state methods to synthesize the tetragonal phase of Ca(WO 4): Tm3+/Yb3+ co-doped with Mg2+ phosphors. Samples with different Mg2+ concentrations (0,3,5,7%) were examined. The upconversion luminescence is detected under 980 nm laser stimulation. The EDAX mapping validated the inclusion of Tm3+/Yb3+ ions and Mg2+ dopants in the Ca(WO 4) host lattice. The luminous characteristics of Ca(WO 4): Tm3+/Yb3+ phosphors were affected by Mg2+ ions. The frequency-dependent dielectric constant, tangent loss, Nyquist graph (Z″ vs. Z′), and ac conductivity were examined from ambient temperature to 100 °C, spanning 100 Hz to M Hz. At room temperature, Jonscher's law showed that electrical resistance decreased at high frequencies in ac-conductivity. These results show that controlled doping may tune phosphor materials' luminous and electrical characteristics, allowing their use in optoelectronic devices and systems. [Display omitted] • The frequency-dependent impedance spectroscopy was studied for the sample. • The samples emitted solid blue emission at (472 nm). • Enriched upconversion emission detected in Mg2+ (5%) sample. • The non-Debye-type nature of the material was performed with Ac-conductivity measurement at room temperature using Jonscher's law. [ABSTRACT FROM AUTHOR]

This study reports the successful preparation of nitrogen-doped carbon quantum dots (N-CQDs) with a quantum yield of 15 % utilizing the hydrothermal method. Citric acid was employed as the carbon source, while 1,3-Diamino-2-propanol was utilized as the dopant. It was discovered that the emission of synthesized N-CQDs was dependent on concentration and excitation. By altering the N-CQDs concentration, the fluorescence emission peak was shifted from 453 to 574 nm, causing the emission to transition from blue to orange. The presence of multiple fluorescence emission centers within N-CQDs was confirmed through two-dimensional fluorescence matrix scanning. As the concentration of N-CQDs increased, the distance between these centers decreased, ultimately leading to aggregation. The energy or electrons were transferred as a result of the surface functional groups' interaction, which ultimately causes the fluorescence emission peak to shift to the red. Furthermore, an increase in concentration results in the formation of larger aggregates and larger sp2 carbon domains, ultimately resulting in longer wavelengths. Because of the convenience of use, high sensitivity, and rapid response of the fluorescent probe detection approach, multi-color N-CQDs with tunable concentration were used for the identification of Fe3+, with a 10–200 μM linear detection range and limits of detection (LOD) of 0.56 μM. [Display omitted] • N-CQDs exhibiting excitation-dependent and concentration-dependent emission were synthesized through the hydrothermal method. • Upon increasing the concentration of N-CQDs, a significant red shift was detected. The N-CQDs exhibited multiple FL centers. • Multi-color N-CQDs exhibited stability and have been effectively utilized for detecting Fe3+ with a LOD of 0.56 μM. [ABSTRACT FROM AUTHOR]

A series of 80TeO 2 - 10Ta 2 O 5 – 10Bi 2 O 3 glasses, anti-glasses and ceramics doped with different concentrations of Er₂O₃, ranging from 0.25 % to 2 % mol, were synthesized to explore their structural transformation and optical properties. The maximum solubility of Er₂O₃ was identified at 1.25 % mol, beyond which the glass transitioned from an amorphous to a crystalline structure. The anti-glasses and ceramics obtained from the heat treatment of the parent glasses were also studied to gain insights into their optical properties. This study reveals a direct relationship between Er3+ ions concentration and full width at half maximum (FWHM) of photoluminescence spectra. The increase in Er3+ ions concentration correlates with a rise in FWHM, indicative of spectral broadening. Anti-glass exhibits a higher emission intensity, followed by ceramic and then glass, reflecting their distinct structural properties. Anti-glass doped with 1 % mol Er 2 O 3 shows an FWHM over 130 nm under 578 mW pumping. The lifetime of the excited state 4I 13/2 increases with the Er 2 O 3 content in the anti-glass and the ceramic, with a notable decrease at 1 % mol Er 2 O 3 ions for both materials, while in glass, the decrease is observed at 0.5 %. Emission cross-sections decrease with increasing Er3+ ions concentration and power, influenced by factors like thermal effects and saturation. The Judd-Ofelt theory highlights structural differences, with glasses having a more disordered structure and with an increase in the Ω₆ parameter across all materials, implying enhanced electric dipole line strength and spontaneous emission probability with higher Er₂O₃ content. Overall, this comprehensive study provides valuable insights into the optical behavior of Er3+ ions in these materials, essential for applications in laser design and optical amplifiers. • Er3+ ions changes glass structure, affecting local fields and forming non-bridging oxygens, influencing FWHM emission values. • A unique trend in Er3+ emission intensity and excited state lifetimes across glasses, anti-glasses, and ceramics. • Emission cross-sections depend on Er₂O₃ content and power, improving lasers and amplifiers in Er3+-doped tellurite materials. • Judd-Ofelt theory shows structural disorder and Er₂O₃ impact on emission probability, offering insights to photonics design. [ABSTRACT FROM AUTHOR]

In this study, the integration of transition metal oxides (TMOs), specifically Cu 2 O and TiO 2 , into a borosilicate glass matrix (30SiO 2 –35B 2 O 3 –35Na 2 O–5CaF 2 -X (TMO)) was investigated for enhanced glass functionality. Glass samples with varying TMO concentrations (X = 0, 1, 2, 3, 4 mol%) were prepared using the melt-quenching technique. X-ray diffraction confirmed the amorphous nature of the synthesized samples, while FTIR analysis showed structural changes, transitioning from trigonal BO 3 to BO 4 tetrahedra, alongside the formation of non-bridging oxygen species due to TMO integration. UV–Vis spectroscopy demonstrated a red shift in optical absorption profiles, correlating with a reduction in the indirect band gap as TMO content increased. Photoluminescence studies showed distinct behaviors, with Cu 2 O suppressing emission peaks and TiO 2 exhibiting intriguing blue and green emissions, diminishing at higher concentrations. It was attributed that Cu 2 O had a larger impact on altering the glass network than TiO 2. These findings contribute to understanding the properties of Cu 2 O and TiO 2 -containing borosilicate glasses, suggesting tailored optical properties for potential applications as bandpass filter and UV blocker. [Display omitted] • Optical properties of Cu 2 O and TiO 2 added in borosilicate glass were studied. • The Cu 2 O and TiO 2 added glass can be employed as band-pass filter and UV blocker. • The Cu 2 O-added glass system has a wide transmission range in 374–640 nm. • TiO 2 -added glass system exhibit absorption in UV region and emission peaks in visible region 465 nm and 557 nm. [ABSTRACT FROM AUTHOR]

Luminescence thermometry using lanthanide-doped nanoparticles has shown to be a forefront approach to measuring temperature at the nanoscale. Such thermometers have a special advantage due to the variety of excitation possibilities, ranging from infrared to ultraviolet. However, it is still uncertain whether the thermometric characteristics of a given lanthanide-based system remain the same regardless of the particular excitation condition. In this work, we investigate the thermometric response of Gd 2 O 2 S : Yb 3 + /Er 3 + nanoparticles under different excitation pathways, using wavelengths in the range between 800 nm and 1600 nm, and also by employing a simultaneous two-color excitation (1510 nm + 859 nm). We observe that the thermal sensitivities are similar under those excitation conditions, ranging from 1.16 %/K to 1.42 %/K, with the highest being obtained with the bichromatic excitation. Also, this non-conventional excitation regime suppresses the luminescence band originated from the transition 2 H 9 / 2 → 4 I 13 / 2 of the Er 3 + ions, which is known to reduce the thermal sensitivity and mask the correct thermometric parameters. This study is a step towards increasing the luminescence thermometers' reliability and accuracy, aiming at robust applications in different areas. • Luminescence thermometry at biologically compatible temperatures. • Thermometric characterization under monochromatic excitation (908 nm, 955 nm, 977 nm, 859 nm, 1510 nm). • Suppression of thermal artifacts under bichromatic excitation (859 nm + 1510 nm). • Distinct thermometric responses depending on excitation condition. [ABSTRACT FROM AUTHOR]

This research investigates the effect of silver (Ag) addition on the photoluminescence enhancement properties of 20Li 2 O–5Bi 2 O 3 -(74- x)TeO 2 –1Er 2 O 3 - x Ag glass samples, aiming to optimize luminescence for applications in optical amplifiers and laser technologies. The enhancement of luminescence properties for both upconversion 4S 3/2 → 4I 15/2 green band and 4F 9/2 → 4I 15/2 red peak luminescence observed are analyzed by quantum yield ξ and relative intensity enhancement (I/I o) parameters. The enhancement on green luminescence properties are observed with high ξ g r e e n and I / I o g r e e n at x < 1 mol% which can be explained within the cavity quantum electrodynamics (CQED) framework due to very low dipolar localized surface plasmon mode volume V eff (∼10–20 × 10−22 m3) allowing stronger quantum size luminescence effect. Meanwhile, the quenching of ξ g r e e n (0.61) at x ≥ 1 mol% may indicate the weaker quantum size luminescence effect. An anomalous enhancement on red luminescence properties with high ξ r e d (2.07) and I / I o r e d (1.79) at x = 1.25 mol% cannot be explained by CQED framework but from phonon-assisted energy transfer (PET) mechanism occurred due to structural changes. The near-field and far-field parameters of AgNP are simulated. Results demonstrated stronger near field electric field distribution enhancement at x = 0.5 mol% and x = 0.75 mol%. This suggests that an optimal AgNP radius exists for promoting the quantum size luminescence effect in our glass samples, falling within the range of 50.00–60.00 nm. Further supporting this conclusion, theoretical calculations using light intensity scattering efficiency (Q sca) revealed the highest values between 50.00 and 70.00 nm of AgNP radius in our glass samples. • Novel glass modified with varying AgNP concentrations enhances photoluminescence properties. • Enhancement in green and red luminescence explained by CQED and electric field distribution. • The research reveals that AgNPs radii between 50 and 60 nm maximise luminescence enhancement. • Theoretical light scattering efficiency (Q sca) calculations support the optimal AgNPs radii. [ABSTRACT FROM AUTHOR]

Transparent 1, 3, 5-Triphenylbenzene doped Stilbene (TBS) single crystal was successfully grown by employing the Bridgman technique. SCXRD studies found crystallographic parameters, which reveal that the TBS single crystal has crystallized in a monoclinic crystal structure with the space group of P2 1 /C. The identification of the functional groups in the TBS crystal was accomplished through the FTIR analysis. The UV–Vis spectral data shows that the TBS crystal exhibits minimal absorption across the visible spectrum, with a lower cutoff wavelength of 365 nm. The violet emission is observed at 380 and 405 nm in the fluorescence analysis. Additionally, the crystal's high quality was confirmed by a full width at half maximum value of 123 arcsec in the prominent rocking curve peak. Third-order nonlinear optical susceptibility χ(3) was determined to be 4.26 × 10−6 esu using the Z-scan technique. These are exciting findings that highlight the TBS crystal's suitability for various applications, including scintillation and optoelectronic device fabrication. • 1, 3, 5-triphenylbenzene doped Stilbene single crystal was successfully grown using the Bridgman technique. • The TBS crystal has minimal absorption in the visible spectrum. • The precise rocking curve peak, with a FWHM of 123 arcsec, effectively showcases the crystal's integrity. • The Z-scan technique confirms the crystal's potential for advanced applications, with a χ(3) value of 4.26 × 10−6 esu. [ABSTRACT FROM AUTHOR]

Rare-earth aluminate garnet-type double oxides have practical applications as scintillators with high luminescence yields; however, several garnet compounds are metastable phases, and those scintillation properties are yet unclear. We prepared Ce3+-doped Gd 3 Al 5 O 12 (Ce3+:GAG) as a thick-film phosphor, using laser-assisted metal–organic chemical vapor deposition, and investigated its luminescence and scintillation properties. With a deposition rate of 48 μm h−1, the Ce3+:GAG thick film was epitaxially grown on a Y 3 Al 5 O 12 single crystal substrate with in-plane orientation relationship. Under UV light and α-ray irradiations, the Ce3+:GAG film exhibited a broad emission centered at 560 nm corresponding to the 5d–4f transition of Ce3+ ions. The scintillation light yield of the Ce3+:GAG film was 14250 photons per 5.5 MeV with a fast decay constant of 82.8 ns for the α-ray irradiation from the 241Am source. • Ce3+:GAG thick film phosphor was epitaxially grown using CVD method. • Ce3+: GAG exhibited photoluminescence at 560 nm due to Ce3+ 5d-4f transition. • Scintillation light yield was 14250 photons per 5.5 MeV, comparable to Ce3+:YAG. [ABSTRACT FROM AUTHOR]

Intrinsic luminescence in Ce-doped (Lu,Y) 2 SiO 5 (or LYSO:Ce) single crystals have been studied by means of excitation luminescence spectroscopy in the vacuum ultraviolet energy range under synchrotron radiation. A previously unreported luminescence band with emission at 250 nm has been discovered as well as its thermal behavior was described in the temperature range 10–120 K. The excitation spectra as well as time-resolved properties of this band suggest that this emission corresponds either to the singlet component of self-trapped exciton or to a self-trapped exciton in the lutetium sublattice of LYSO single crystals. • New previously unreported intrinsic emission band at 250 nm has been observed in LYSO single crystals. • Temperature dependencies of intrinsic luminescence have been measured and analyzed. • Two possible origins of new 250 nm emission are proposed and discussed. [ABSTRACT FROM AUTHOR]

In this work, a series of broad-band green phosphors SrLaScO 4 : x Bi3+ (x = 0–0.1) were synthesized using the traditional solid-state method, and the luminescence was effectively enhanced via multi cationic partial substitution strategy. The SrLaScO 4 : x Bi3+ phosphors all exhibit a wide emission band with a full width at half-maximum (FWHM) of 115–148 nm in the range of 450–700 nm upon excitation at 333 nm, effectively filling the cyan gap and peaking at 505 nm. It is proved that the observed luminescence originates from both the 3P 1 state of Bi3+ in [(Sr/La)O 8 ] site and the Bi3+ - to - Sc3+ metal to metal charge transfer (MMCT) state. The optimal concentration of Bi3+ doped SrLaScO 4 phosphor is 1 at%, and the concentration quenching mechanism is the dipole-dipole interaction. Remarkably, the luminescence intensity of the phosphor is 198.4 % increased by partially replacing Sr2+ ions with Mg2+. Due to the good matching of the excitation wavelength of the phosphor with the near-UV chip, a high-quality WLED device with color stability and high color rendering index (Ra = 92.1) was prepared by combining commercial phosphor with SrLaScO 4 :0.01Bi3+ phosphor. We anticipate that this work can provide new ideas for finding high-performance phosphors for high color rendering index pc-WLED. • SrLaScO 4 :Bi3+ exhibit broad-band green emission, effectively filling the cyan gap. • The luminescence is effectively enhanced via multi-cationic sites engineering. • The pc-WLED devices prepared with SrLaScO 4 :0.01Bi3+ exhibit high CRI (Ra = 92.1). [ABSTRACT FROM AUTHOR]

Upconverted afterglow imaging presents a promising avenue for long-term auto-fluorescence-free imaging applications without the necessity of expensive time-resolved equipment. In this research, inspired by LED design, we devised a straightforward ternary upconverted afterglow conversion (UAC) strategy that amalgamates upconversion NaYbF 4 : Tm 0.005 (UP), afterglow ZnS:Cu,Co (AP), and color conversion CaAlSiN 3 :Eu phosphors (CP). This fusion resulted in a UAC composite that displays a deep-red to near-infrared (NIR) afterglow with a peak at 663 nm, following a brief activation period by 980 nm light. Importantly, an enhancement of 116 times was realized by using the UAC strategy when comparing with a typical single phase afterglow phosphor, Zn 3 Ga 2 SnO 8 :Cr,Yb,Er. The NIR-rechargeable afterglow sustained for a minimum of 100 min after a mere 3 s of NIR wireless charging process and is chemically stable. This makes it highly suitable for long-term luminescence imaging applications. To demonstrate its potential, we employed our ternary UAC phosphor to image medical plastic prostheses through pig skin in vitro and simulated a plastic surgery on a mouse model in vivo. Such luminescent information could prove invaluable for planning future surgical interventions, such as prosthesis replacement, removal, or necessary debris cleaning. [Display omitted] • NaYbF 4 :Tm was used as a wireless upconversion charger using NIR light as energy. • ZnS:Cu,Co was found to be an outstanding energy accumulator with intense afterglow. • CaAlSiN 3 :Eu was used as a color conversion phosphor to adjust spectrum for bioimaging. • The composite realized 116 times more intense afterglow than Zn 3 Ga 2 SnO 8 :Cr,Yb,Er. • The composite was used to prepare self-luminescent prosthesis in vivo. [ABSTRACT FROM AUTHOR]

Rare earth ion doped fluorescent powder, as a key material for the application of white light-emitting diodes (w-LEDs), green components often face the problem of poor thermal stability. Developing fluorescent powders with excellent thermal stability is of great significance. This article synthesized a series of Gd 5 Si 2 BO 13 :Tb3+ blue phosphors and non rare earth Bi3+ ion doped Gd 5 Si 2 BO 13 :Tb3+ green phosphors using a high-temperature solid-phase method. The phase structure and photoluminescence characteristics of the sample were analyzed in detail through XRD, excitation and emission spectra, as well as attenuation curves. The energy transfer from Bi3+ to Tb3+ was studied and confirmed through photoluminescence spectra and lifetime decay curves. Research has shown that the addition of Bi3+ significantly enhances the emission intensity of Tb3+ in the near ultraviolet range, and tunes the emission color of Gd 5 Si 2 BO 13 :Bi3+ and Tb3+ from blue to green, attributed to the energy transfer from Bi3+ to Tb3+. In addition, the addition of Bi3+ increased the thermal stability of single doped fluorescent powder Gd 5 Si 2 BO 13 :0.55Tb3+ from 88.21 % to 92.82 % at 150 °C, proving that the Gd 5 Si 2 BO 13 :Bi3+ and Tb3+ samples have good thermal stability. This study not only deepens our understanding of the new main material Gd 5 Si 2 BO 13 , but also provides a reference for the development of green phosphors with excellent thermal stability. [Display omitted] • A series of Gd 5 Si 2 BO 13 :Bi3+, Tb3+ phosphors were successfully synthesized. • The co-doped Gd 5 Si 2 BO 13 :Bi3+, Tb3+ phosphors have excellent emission intensity and thermal stability. • The Gd 5 Si 2 BO 13 :Bi3+, Tb3+ green phosphors is promising for use in high-power LED lighting devices and backlight displays. [ABSTRACT FROM AUTHOR]