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BaGeTeO6: Nd3+/Yb3+/Ho3+ green up-conversion phosphors were synthesized using the high-temperature solid-state reaction method. The optimal doping concentrations for the three dopant ions Nd3+, Yb3+, and Ho3+ were determined to be 1 mol%, 6 mol%, and 0.8 mol%, respectively, through the method of controlling variables. By analyzing the dependence of the up-conversion luminescence intensity on the pump current of the 980 nm laser, it was found that the green and red up-conversion emissions of Ho3+ ions under 980 nm laser excitation were both two-photon processes. Furthermore, the influence of temperature on the up-conversion luminescent properties of BaGeTeO6: Nd3+/Yb3+/Ho3+ green up-conversion phosphors under 980 nm laser excitation was investigated, and the temperature sensing properties of Ho3+ ions were discussed. The results indicated that, at room temperature and higher temperatures, both the red and green up-conversion emissions of the sample were two-photon processes. Within the range of excitation current used in the experiment, the ratio of red to green up-conversion luminescence intensity of Ho3+ ions was independent of the laser excitation current but correlated with the sample temperature. In the temperature range of 303–723 K, the ratio of red to green up-conversion luminescence intensity of Ho3+ ions exhibited a nonlinear relationship with temperature. Comparing the temperature sensing sensitivity of Ho3+ in different matrices, the results indicated that the sample possessed high temperature sensing sensitivity. [ABSTRACT FROM AUTHOR]

Laser illumination is considered to be a revolution of new lighting technology due to its high efficiency and pure color. Similar to the white Light Emitting Diode (LED), phosphor convertor is also a necessary component to generate light in laser illumination technology. In order to improve the performance of laser, designing and optimizing phosphor with high color purity is an effective method. In our study, the pure-red Sr2GdTaO6:Er3+/Yb3+ powders were synthesized and optimized using a high-temperature solid-phase method. The phosphor structure of the obtained phosphors was analyzed through X-ray diffraction (XRD), confirming all products are Sr2GdTaO6 polycrystalline powders. Theoretical models, optimized through experimental design, established regression equations correlating Er3+/Yb3+ doping concentrations with luminescence intensity. Leveraging a genetic algorithm, the optimal solutions for the equations were calculated, resulting in Er3+ and Yb3+ doping concentrations of 4.99% and 24.85% under 980 nm laser excitation and 4.95% and 23.19% under 1550 nm laser excitation, respectively. Under the same conditions, the up-conversion fluorescence emission spectra of the samples were measured, revealing strong green and red emissions with peaks at 550 nm, 563 nm, and 663 nm, corresponding to transitions from 2H11/2 → 4I15/2, 4S3/2 → 4I15/2, and 4F9/2 → 4I15/2 energy levels. For the optimal samples at 980 nm and 1550 nm, the relationship between up-conversion luminescence and laser operating current was explored, indicating that the up-conversion luminescence in these two cases is a two-photon and three-photon process, respectively. The up-conversion luminescence mechanism was analyzed and discussed in detail. Additionally, the relationship between up-conversion fluorescence and temperature was investigated for the optimal samples, revealing excellent temperature-sensing characteristics for up-conversion emissions excited by both 980 nm and 1550 nm lasers. The CIE coordinates (0.5986, 0.3973) and (0.7089, 0.2910) of the optimal sample were calculated under excitation at 980 nm and 1550 nm wavelengths. [ABSTRACT FROM AUTHOR]

In recent years, the rare earth doped upconversion luminescent materials have been widely used in many fields. In practical applications, we observed that various dopants have distinct effects on different substances to some extent. In this context, we have successfully synthesized a dual-mode-excited Ca3TeO6 double perovskite. After introduce the Yb3+/Er3+ ions pair, the designed phosphor can emit green and red luminescence under 980 nm and 1550 nm excitation, respectively, making it suitable for diverse scientific and technological applications. The potential up-conversion mechanisms driven by different excitation sources have been investigated. Moreover, it was discovered that adjusting the molar ratio of Er3+ and Yb3+ ions enhances the performance of the studied materials, rendering them well-suited for application as a high-quality optical thermometer based on the FIR technique. Our results clearly indicate that Er3+/Yb3+ co-doped Ca3TeO6 phosphors allows for multiple optimizations and control of material properties, showcasing great potential for applications in various field. [ABSTRACT FROM AUTHOR]

In this paper, a series of Sr0.96Al2Si2O8 phosphors doped with 0.02Eu2+ and 0.02Re3+ (where Re = Tm, Dy, Er, Nd, Sm, La, Ho) were synthesized using the high-temperature solid-phase method at 1350 °C for 4 hours. The samples underwent characterization for structural and phase analysis using XRD-6000. Fluorescence and photostimulated properties were evaluated with F-4600. The pyroluminescence curve indicates a trap depth of 0.6-0.8 eV for Sr0.96Al2Si2O8: 0.02Eu2+, 0.02Re3+ (where Re = Dy, Er, Sm, La, Ho), making it suitable for prolonged afterglow luminescence. In comparison with deep trap material Sr0.96Al2Si2O8: 0.02Eu2+, 0.02Nd3+, the generated traps approach or exceed 1 eV, suggesting its potential for use as a light excitation and optical storage material. Additionally, the correlation between sample TL and PSL was examined, confirming that the augmentation of initial photostimulated luminescence intensity is closely associated with the generation of new traps. Furthermore, considering the effect of different trivalent lanthanide rare earth ion doping on trap depth from a trap regulation perspective offers a potential avenue for elucidating the nuanced processes underlying photostimulated luminescence. [ABSTRACT FROM AUTHOR]

A series of YNbO4:Ho3+/Yb3+ phosphors with varying concentrations of Yb3+ were synthesized using a high-temperature solid-state method. To ascertain the presence, structure, and purity of YNbO4:Ho3+/Yb3+, the crystal structure of the luminescent powder was investigated through x-ray diffraction. Trivalent rare earth ion-doped transparent luminescent materials possess distinctive f–f transition properties, which can be comprehensively studied using the Judd–Ofelt theory. However, when dealing with opaque powder materials, traditional Judd–Ofelt (J–O) theory becomes challenging to apply due to the unavailability of absorption spectra measurements. In this paper, to analyze the properties of Ho3+ in the YNbO4 phosphors, diffuse diffraction spectra and fluorescence decay curves were employed within the framework of the J–O theory. Furthermore, the J–O parameters Ωλ (λ = 2, 4, 6) of Ho3+ in YNbO4 phosphors were calculated and subsequently modified for accuracy and precision. [ABSTRACT FROM AUTHOR]