Eu3+-activated Sr-2 InSbO6 (SISO) orange-red-emitting double-perovskite antimonate phosphors were realized. The emission spectrum of SISO:Eu3+ sample exhibited a strong orange-red emission band at 594 nm under 395 nm excitation. Judd-Ofelt theory analysis indicated the Eu3+ ions were in the symmetrical environment of SISO host lattice. The fabricated white light-emitting diode presents a high R-a and a good CCT. For the visualization of latent fingerprints (LFPs), the hydrophilic SISO:Eu3+ phosphor was converted into hydrophobic SISO:Eu3+@OA phosphor by coating oleic acid (OA). The SISO:Eu3+@OA phosphor could show reliable level 1-3 fluorescent images of LFPs with high contrast and resolution. The LFPs still exhibited the excellent visualization on the various substrates (glass, aluminum foil, stainless steel, compact disk, student card, and so on). These results indicate the SISO:Eu3+ products have great potential applications for WLEDs and visualization of LFPs.

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.

Novel orange-red Sr3LaNb3O12 (SLNO):xSm3+ (0.01 <= x <= 0.03) phosphors are successfully prepared using the traditional solid-state method. The feasibility that the SLNO compounds can act as an appropriate host has been effectively demonstrated by unit cell structure and bandgap structure. The phase purity, particle size distribution, and elemental composition of SLNO:Sm3+ phosphors are studied. The luminescence properties, concentration -quenching mechanism, color purity, thermostability, CIE chromaticity coordinates, and correlated color tem-perature (CCT) of the obtained SLNO:Sm3+ products are also discussed. Under 408 nm excitation, SLNO:0.10Sm3+ sample emits a bright orange-red light at 598 nm owing to the 4G5/2 to 6H7/2 transition of Sm3+. The concentration-quenching mechanism is found to be dipole-dipole interaction by the calculated Rc value (17.12 angstrom) and Dexter's theory. Impressively, the color purity of the phosphors is high and stable (all reach 99.9%), which is rarely affected by the Sm3+ doping concentration. It is worth noting that the obtained phos-phors exhibit an abnormal thermal quenching (ATQ) behavior, increasing by 16.12% from 300 to 380 K (SLNO:0.10Sm3+). The CIE x and y chromaticity coordinates vary slightly with the change of temperature, indicating a good thermostability. The mechanism of ATQ has been studied as the lattice defects, and the thermal activation energy is calculated to be 0.51 eV. Ultimately, a white-light-emitting diode (w-LED) with a high color rendering index (Ra) of 88 and a CIE chromaticity coordinate of (0.333, 0.333) has been prepared. The results above reveal the potential of SLNO:Sm3+ to be widely used in w-LEDs.

The Mn4+-doped Ca2MgTeO6 (CMTO) far-red emitting phosphors with double perovskite-type structure were successfully synthesized. Upon near-ultraviolet (n-UV, 300 nm) light excitation, the as-prepared phosphors showed far-red light at 700 nm attributed to the (2)Eg ->(4)A(2g) transition of Mn4+ ion. The doping concentration of the CMTO:xMn(4+) samples was optimized to be 0.8 mol%. The relevant mechanism of concentration quenching was demonstrated as the dipole-dipole interaction. Furthermore, solid solution and impurity doping strategies were adopted to improve the far-red emission of the luminescence-ignorable CMTO:Mn4+ phosphor. Series of Ca2MgTe(1_y)WyO6:0.8 mol%Mn4+ (y = 0-100 mol%) solid solution and Ca(2-z)Ln(z)MgTe(0.6)W(0.4)O(6):Mn4+ (Ln = La, Y, and Gd, z = 10 mol%) phosphors were synthesized through the above two strategies. The luminescence intensity of the optimal Ca1.9Gd0.1MgTe0.6W0.4O6:Mn4+ phosphor was 13.7 times that of the CMTO:Mn4+ phosphor and 2.51 times that of red commercial phosphor K2SiF6:Mn4+. Notably, both CMTO:Mn4+ and Ca1.9Gd0.1Mg-Te0.6W0.4O6:Mn4+ phosphors exhibited remarkable thermal stability compared with most Mn4+-doped phosphors. Finally, the highly efficient Ca1.9Gd0.1MgTe0.6W0.4O6:Mn4+ phosphor was successfully applied in fabricating the warm white light diode (w-LED). This working along both lines strategy exhibited great potential for luminescence optimization of Mn4+-doped oxide phosphors.

In this study, Sm3+-doped double-perovskite Mg2InSbO6 phosphors were synthesized via high-temperature solid-state reaction. Mg2InSbO6 belongs to the double-perovskite family with a space group of R3 over bar (No.148). The photoluminescence (PL) spectrum illustrates that Mg2InSbO6:0.05Sm(3+) phosphor can emit intense orange-red emission light at 607 nm due to the (4)G(5/2)-> H-6(7/2) transition. The optimum concentration of Mg2InSbO6:xSm(3+) is confirmed to 0.05 mol. The asymmetric ratio ((4)G(5/2)-> H-6(9/2)/(4)G(5/2)-> H-6(5/2)) of Mg2InSbO6:0.05Sm(3+) phosphor is 2.73. The quenching temperature exceeds 500 K, illustrating that Mg2InSbO6:Sm3+ sample has excellent heat resistance. The high color purity and correlated color temperature (CCT) of Mg2InSbO6:Sm3+ phosphors are obtained. Furthermore, a white light-emitting diode (w-LED) is successfully fabricated, possessing CCT of 6769 K and high color rendering index (R-a) of 89. Therefore, the orange-red-emitting Mg2InSbO6:Sm3+ phosphors exhibit great potential to apply in solid-state lighting fields.

Carbon dots (CDs) are being increasingly favored by researchers due to their suitable size, simple preparation method, low cost, and excellent optical performance. However, CDs are often self-quenched in the solid state, limiting their application and development. In this work, blue/red-CDs (B/R-CDs) materials are synthesized using hydrothermal method. By combining CDs with Mg(OH)2 hexagonal nanosheet in one step, a series of B/R-CDs@Mg(OH)2 anti-self-quenching luminescent composites with dual characteristic peaks at 447 and 677 nm was then synthesized. Their photoluminescence (PL) spectra are consistent with the blue and red spectrum, which match well with the absorption of chlorophyll a and chlorophyll b. The emissive colors are also tunable by various weight ratios of these composites. These materials have the excellent thermal stability and photostability. light-emitting diodes (LEDs) and light-conversion films for plant growth are further prepared and studied. Results indicate that the materials have excellent commercial horticulture applications in plant-growth lamps and light-conversion film. (c) 2021 Published by Elsevier B.V.

Using Camellia oleifera shell (COS) as a raw material and phosphoric acid as the activator, activated Camellia oleifera shell carbon (COSC-0) was prepared and then modified by Fenton's reagent (named as COSC-1). SEM, GC-MS, FTIR, and specific surface area and pore analyzers were used to study the adsorption performance of COS, COSC-0, and COSC-1 on cooking fumes. Results showed that COSC-1 was the best adsorbent compared with COS and COSC-0. The adsorption quantity and penetrating time of COSC-1 were 44.04 mg/g and 4.1 h, respectively. Most aldehydes could be adsorbed by COSC-1, which was due to the large number of carbonyl and carboxyl groups generated on the surface of COSC-1 from the action of Fenton's reagent. The adsorption effect of COSC-1 on different types of pollutants in cooking fumes was analyzed based on the similar compatibility principle. COSC-1 showed a much higher adsorption effect on the strong polarity functional groups than on weak polar groups. The results provide a theoretical basis for the application of Camellia oleifera shell carbon adsorption technology in the treatment of cooking fumes.

In this study, novel deep-red-emitting Mg2InSbO6:Mn4+ phosphors were prepared through a high-temperature solid-state reaction. The as-prepared phosphors belong to the perovskite structure with the space group of R (3) over bar (No.148). The calculated energy gap value of Mg2InSbO6 is similar to 1.788 eV. Emission spectrum of the Mg2InSbO6:0.3%Mn4+ was obtained under 301 nm excitation, which centered 665 nm due to the E-2(g) ->(4)A(2g) transition. The optimum concentration of Mg2InSbO6:xMn(4+) is confirmed to 0.3% mol, and the concentration quenching effect is ascribed to the dipole-dipole interaction. The relative temperature-dependent PL spectra demonstrate that phosphors possess commendable repeatability and high activation energy. The chromaticity shift diagram shows the phosphors have good resistance of color drifting. The Mg2InSbO6:0.3%Mn4+ phosphor has a high color purity of 99.8%. Furthermore, a red light-emitting diode is fabricated with Mg2InSbO6:0.3%Mn4+ phosphor and a 365 nm near-ultraviolet chip. The emission spectrum of the red LED is perfectly overlapped with plant pigments (chlorophyll a and chlorophyll b) absorption spectrum. Thus, Mn4+-activated Mg2InSbO6:Mn4+ phosphors have the potential to apply in plant-cultivation LEDs.

LaNb2VO9:Dy3+ yellow phosphors were synthesized by high-temperature solid-state method. The luminescent properties, structure, and color purity of the products were studied systematically. LaNb2VO9:Dy3+ phosphors can be effectively excited by two broad charge transfer bands (CTB) under 307 nm excitation. The strong yellow light at 570 nm was caused by the F-4(9/2) -> H-6(13/2) energy level transition of Dy3+. The optimum doping concentration of LaNb2VO9:0.1Dy(3+) phosphor was x = 0.10 mol, and the dominant factor of concentration quenching effect is the nearest-neighbor ions interaction. The chromaticity coordinates of International Committee LaNb2VO9:Dy3+ were located in the yellow color area. In addition, LaNb2VO9:0.1Dy3+ phosphor can well visualize the latent fingerprint (LFP) image and lip print image. The levels 1-3 features of fingerprint and groove pattern of lip print can be easily recognized, with high resolution and contrast. The experimental results showed LaNb2VO9:Dy3+ can be well applied to LFP and lip print detection.