A series of ScNb2VO9:xEu3+ (x = 0.5, 1, 2, 5, 20, 30, 40, and 45 mol%) red-emitting phosphors was achieved by the high-temperature solid-state reaction. The ScNb2VO9:20 mol%Eu3+ phosphor exhibits a red emission around 618 nm (5D0 -> 7F3 transition) under 324 nm excitation. The phosphor presents the wide excitation with charge transfer band (CTB) from O2--V5+ and O2--Eu3+ transitions between 225 and 360 nm. The prepared ScNb2VO9:20 mol%Eu3+ phosphor shows high thermal stability, high moisture resistance stability, and high UV radiation stability. The features of the latent fingerprint (LFP) created by ScNb2VO9:Eu3+@oleylamine can be clearly reflected on different surfaces based on the powder dusting method. The experiment results demonstrate the superiority of the ScNb2VO9:Eu3+ phosphor in the field of LFP development.

New Sm3+ doped Cd2MgTeO6 tellurate red-emitting phosphors with Na+ ions as charge compensation were obtained using a high-temperature solid-state approach at 1000 degrees C. During this study, the prepared phosphors were subjected to phase purity, particle morphology, luminescence characteristics, thermal stability, and Com-mission Internationale de L & PRIME; Eclairage (CIE) chromaticity. The critical quenching concentration of Sm3+ doped Cd2MgTeO6 phosphor was 2 mol%. According to Dexter's theory and the calculated Rc value (22.21 & ANGS;), the dipole-dipole interaction causes the phenomenon of concentration quenching. Particularly, the Cd2MgTeO6:2 mol%Sm3+, 2 mol%Na+ phosphor exhibited an evident red-light emission (647 nm) at & lambda;ex = 407 nm because of the 4G5/2 to 6H9/2 level transition of Sm3+. Its internal quantum efficiency (IQE) was 38.87%. It is worth noting that the Cd2MgTeO6:Sm3+, Na+ phosphor exhibited abnormal thermal quenching (ATQ) characteristics, and the luminous intensity of the Cd2MgTeO6:2 mol%Sm3+, 2 mol%Na+ increased by 7.20% at 480 K compared with the initial temperature. In addition, white LEDs and red LEDs were successfully manufactured with a 408 nm chip. The prepared red LED showed the emission spectrum similar to the absorption spectrum of Phytochrome Pr, which is expected to be applied in plant growth. The w-LED had a CCT (correlated color temperature) of 4790 K, color rendering index of 91, and color coordinates of (0.348, 0.335). Therefore, the Cd2MgTeO6:Sm3+, Na+ phosphor has demonstrated potential applications in w-LEDs and plant growth LEDs.

In the present work, a series of zincate CaY2Sb2(ZnO4)(3):Eu3+ phosphors were successfully obtained via the conventional solid-state method at high temperature. The phase purity, morphology, element mapping, photo-luminescence excitation/emission (PLE/PL), and decay time of the obtained phosphors were investigated systematically. Results show that the synthesized samples demonstrate the strongest red-emitting peak at 610 nm under the n-ultraviolet (n-UV) 395 nm excitation. The Judd-Ofelt parameters (omega 2, omega 4), radiative transition rates, and branching ratios (beta 0J, J = 2, 4) of CaY2Sb2(ZnO4)3:Eu3+ to explore the Eu3+-coordinated environment in the host matrix. The concentration quenching of CaY2Sb2(ZnO4)3:2xEu3+ phosphors happened until at high doping concentration of x = 50 mol%. CaY2Sb2(ZnO4)3:100 mol%Eu3+ sample presented the excellent thermal stability with abnormal thermal quenching behavior. Compared with the commercial Y2O3:Eu3+ red phosphor, the luminescent intensity of the prepared phosphor is 1.14 times stronger. The high internal quantum efficiency (IQE) of CaY2Sb2(ZnO4)3:100 mol%Eu3+ phosphor is 79.20%. In addition, the fabricated red and white light -emitting diodes (w-LEDs) both emit bright light. The w-LED demonstrates a high color rendering index (Ra = 96) and a low correlated color temperature (CCT = 5249 K). Therefore, the prepared red-emitting phosphor has a promising application in w-LEDs.

In this work, a series of double perovskite red-emitting NaSrLaTeO6:xSm3+ phosphors were successfully syn-thesized through the traditional high-temperature solid-state method. The NaSrLaTeO6 lattice has a cubic structure, which possesses the Fm-3m (225) space group. Under 406 nm excitation, NaSrLaTeO6:Sm3+ phosphors can exhibit four emission peaks at 564, 599, 645, and 711 nm, which are ascribed to the 4G5/2 -> 6HJ (J = 5/2, 7/ 2, 9/2, and 11/2) transitions. The asymmetry ratio of NaSrLaTeO6:5 mol%Sm3+phosphor is calculated to be 6.11. The CIE chromaticity coordinates of NaSrLaTeO6:xSm3+ (1 mol% <= x <= 30 mol%) phosphors change slightly with the increase in doping concentrations. The phosphors possess low correlated color temperature (CCT) and high color purity (>99.6%). The prepared NaSrLaTeO6:5 mol%Sm3+ phosphor shows the excellent thermal stability with a high quenching temperature (T0.5 > 500 K) and activation energy (Ea = 0.31 eV). Furthermore, the NaSrLaTeO6:Sm3+ phosphors have the good resistance to color drifting (chromaticity shift Delta E = 0.011 at 420 K). The w-LED was fabricated with a 402 nm chip through the trichromatic method. It has good CIE chromaticity coordinates (0.325, 0.310), high Ra (89), and CCT (5889 K). Consequently, the red-emitting NaSrLaTeO6:Sm3+ phosphors would be anticipated to be used in w-LEDs.

In this report, a Sm3+-activated LaTiSbO6 (LTSO) orange-red-emitting double-perovskite antimonate phosphor was realized via a solid-state reaction process. The synthetic LTSO:Sm3+ phosphors were fully analyzed in terms of phase purity, elemental composition, and luminescence properties. The X-ray diffraction (XRD) pattern confirmed that all diffraction peaks are well-matched with the standard data card (PDF#33-0726). The crystal structure consists of the trigonal cell with the space group P31 m (No.162). At excitation level of 403 nm, the emission of LTSO:Sm3+ presents four distinct peaks located at 567, 598, 645, and 711 nm, corresponding to the 4G5/2-6HJ/2 (J = 5, 7, 9, and 11) transitions, respectively. Experimental results verify that the optimal doping concentration of Sm3+ is 0.05 mol. The concentration quenching mechanism of the dipole-dipole interaction according to Dexter theory. The LTSO:0.05Sm3+ phosphor exhibits good thermal quenching behavior with a high activation energy (Ea = 0.308 eV). The fabricated white light-emitting diode (WLED) device presents a high rendering index value (Ra) of 90 and a good correlated color temperature (CCT) of 5536 K. These results indicate the LTSO:Sm3+ products have great potential for WLEDs applications.

Recently, rare-earth doped phosphors have been newly developed and applied in hot issues such as phosphor-converted light-emitting diodes (pc-LEDs), anti-counterfeiting, and fingerprint visualization. Herein, an Eu3+-activated CaGdSbWO8 (CGSW) red phosphor was synthesized by a high-temperature solidstate reaction. The phosphors can exhibit narrow red-light emission at 614 nm due to the electric dipole transition (D0 -> F2)-D-5-F-7 of Eu3+. Impressively, this phosphor has excellent thermal stability, its emission intensity of optimum sample doped with 0.30 Eu3+ remained 90.61% at 420 K and thermal quenching temperature exceeds 480 K. The Commission International del'Eclairage (CIE) chromaticity coordinates of CGSW:0.30Eu(3+) are (0.662, 0.338) with a high color purity (98.5%). The fabricated white light diode (w-LED) has a high color rendering index (91.4) and a low correlated color temperature (4986 K) with CIE coordinates (0.343, 0.327). Further experimental results showed that the prepared security ink can be applied to anti-counterfeit labels and information encryption. The latent fingerprint developed by CGSW:0.30Eu(3+) phosphor present the excellent selectivity and contrast. The level 1-3 structural characteristics of latent fingerprints could be well identified under ultraviolet irradiation. Therefore, the Eu3+-activated CGSW red emitting phosphor has broad application prospects due to its excellent luminescence properties. (C) 2022 Published by Elsevier B.V.

Due to outstanding optical characteristics of phosphors, they have recently been applied to various fields, such as solid-state lighting, forensic science, and laser technology. Herein, a series of Mg2InSbO6:xEu(3+) (x = 0.005-0.25) phosphors with pure red emission were prepared via high-temperature solid-state reaction. Under near-ultraviolet 395 nm excitation, photoluminescence spectra of Mg2InSbO6:Eu3+ (MISO:Eu3+) phosphors exhibited a bright red luminescence peak at 612 nm, which is attributed to D-5(0)-> F-7(2) transition of Eu3+. The thermal quenching temperature of the optimum sample exceeded 480 K, which is much higher than the working temperature of light-emitting diode (423 K). The packaged white light-emitting diode (WLED) had CIE coordinates of (0.336, 0.340) with correlated color temperature of 5322 K and color rendering index value of 90. Furthermore, the latent fingerprints (LFPs) stained with MISO:Eu3+ phosphors were visualized with level 1-3 features, but their accuracy was relatively low. Therefore, oleic acid (OA) was utilized to form a hydrophobic coating on MISO:Eu3+ powders to improve fingerprint development, and the higher accuracy of level 1-3 features was achieved, especially level 3 features. The LFPs on smooth and rough surfaces stained with MISO:Eu3+@OA phosphors were easily collected at high contrast under 395 nm light. The obtained results prove that MISO:Eu3+ and MISO:Eu3+@OA can be considered as promising red phosphors for WLED and LFP identification and provide insight into the improvement of LFP development. (C) 2021 Elsevier B.V. All rights reserved.