Optical properties of Sm3+ and Tb3+ co-doped CaMoO4 phosphor for temperature sensing.

Abstract

We prepared CaMoO4: x%Sm3+, 5%Tb3+ (x = 0.1, 0.5, 1, 2) phosphors by a precipitation method. Based on the diversity in thermal quenching behavior of different ions in molybdate, a novel thermometry strategy has been proposed. The fluorescence intensity ratio (FIR) of Sm3+ to Tb3+ in these composites exhibits remarkable temperature dependence due to the diverse thermal quenching behaviors of Sm3+ and Tb3+ ions. Excellent temperature sensitivity was achieved from 293 K to 593 K, suggesting that these can perform thermometry. The sensitivities increase with Sm3+ concentration. The maximum sensitivity is as high as 0.312 K-1 (at 593 K) when the Sm3+ concentration is 2%. However, the low Sm3+ concentration sample has a greater relative sensitivity; the maximum value is as high as 0.019 K-1 (at 460 K) when the Sm3+ concentration is 0.1%. Lower Sm3+ concentrations suggested a greater range of luminescent color changes with temperature. Thus, the sample with less Sm3+ can measure temperature via luminescent color.