Excellent upconversion luminescence and temperature sensing performance of CdMoO4:Er3+,Yb3+ phosphors.

In this paper, Er3+/Yb3+ co-doped CdMoO4 phosphors were prepared by a traditional high temperature solid state reaction method. Based on the 3D network structure of the CdMoO4 host and the efficient Er3+/Yb3+ upconversion luminescence combinations, excellent green emission properties were observed when the prepared sample is irradiated with a laser at about 980 nm. For optical temperature sensors based on the fluorescence intensity ratio (FIR), the prepared phosphors have excellent sensitivity to temperature in the range of 293 to 473 K. With increasing environmental temperatures, the absolute sensitivity of the CdMoO4:0.02Er3+,0.08Yb3+ sample reached a maximum at about 473 K (Sa = 1.388% K-1). The calculated relative sensitivity of the optical temperature sensor was Sr = 1.631% K-1 at 293 K. This is due to the sensitive thermally coupled energy levels (TCLs) of the Er3+ ions (2H11/2 and 4S3/2) in the CdMoO4 structure. Therefore, it is shown that the prepared CdMoO4:0.02Er3+,0.08Yb3+ phosphor has excellent applications in non-contact optical temperature measurement.

Bifunctional application of La3BWO9:Bi3+,Sm3+ phosphors with strong orange-red emission and sensitive temperature sensing properties.

Through a solid-phase reaction technique, Sm3+ and Bi3+ co-doped La3BWO9 phosphors with high emission intensity and sensitive temperature sensing properties have been successfully synthesized. Based on XRD Rietveld refinement, the optimized crystal structure was used as the original model to calculate the band structure and partial density of states (PDOS) by density functional theory (DFT) calculations. The luminescence characteristics of Sm3+ and Bi3+ co-doped La3BWO9 phosphors were measured and analyzed. In addition, the optimal doping concentrations of Sm3+ and Bi3+ were investigated. The luminescence properties of Sm3+ doped phosphors were optimized by introducing Bi3+ ions. Efficient energy transfer from Bi3+ to Sm3+ ions was observed in La3BWO9:Sm3+, Bi3+ phosphors. An optical temperature sensor with high sensitivity was designed based on the different thermal quenching properties of Sm3+ and Bi3+ ions. In the temperature range of 293-498 K, the optimum absolute sensitivity (Sa) and maximum relative sensitivity (Sr) were 2.88 %K-1 and 1.32 %K-1, respectively. These results indicated that the prepared La3BWO9:Bi3+, Sm3+ phosphors have wide application prospects as solid state lighting materials and optical temperature sensors.