Extremely intense pure green upconversion luminescence in Ho3+/Yb3+ co-doped BiTa7O19 phosphors under 980 nm laser excitation.

A series of BiTa7O19(BTO):Ho3+/Yb3+ phosphors were prepared by high-temperature solid state sintering, which exhibited outstanding pure green upconversion luminescence (UCL) under 980 nm laser excitation. When Ho3+ doping 10 mol%, Yb3+ has almost no concentration quenching point. By optimizing the preparation process, the phase purity of the sample can be improved. Under 980 nm laser excitation power density of 124.99 W/cm2, the UCL intensity of the optimized sample is 1.79 times that of the non-optimized sample. The maximum relative temperature sensitivity SR of 0.384% K−1 at 557 K and 0.40% K−1 at 723 K can be obtained by using luminescence intensity ratio (LIR) technique. All experiments show that BTO is an excellent UCL host, and BTO:Ho3+/Yb3+ can be used in UCL display and temperature sensing. [ABSTRACT FROM AUTHOR]