Up-Conversion Luminescence and Temperature Characteristics Study of Ho3+/Yb3+ Co-doped NaGd(MoO4)2 Phosphors.

In order to obtain the maximum up-conversion luminescence intensity of Ho3+/Yb3+-doped NaGd(MoO4)2 phosphors, samples with 1.00%Ho3+/22.89%Yb3+ doping concentration were prepared by high-temperature solid-phase method. The doping concentration of 1.00%Ho3+/22.89%Yb3+ corresponds to the maximum luminescence intensity of red light excited by a 980 nm laser. X-ray diffraction analysis showed that the prepared samples were in pure NaGd(MoO4)2 phase. Under the excitation of a 980 nm laser, the measured and theoretical luminescence intensities of the optimal sample are close to each other. The relationship between different pumping currents and up-conversion luminescence intensity was tested. The red light of the sample was proved to be a two-photon process. Up-conversion luminescence mechanism of the sample was discussed in detail. Finally, we measured the emission spectrum of the optimal sample in the up-conversion to temperature. It was fitted using the fluorescence intensity ratio formula, and its relative sensitivity was calculated to be 0.0204 K-1 at 440 K. [ABSTRACT FROM AUTHOR]