Thermal enhancing luminescence and thermal quenching luminescence of Sc2(MoO4)3: X mol% Eu3+

Abstract

The synthesis of a series of Sc2(MoO4)3: x mol% Eu3+ red phosphors (x = 0, 1, 3, 5, 7, 10, 15, 20, 30, 50, 70 and 100) was successfully completed through the implementation of a high-temperature solid-phase synthesis methodology. The optimum 5 mol% Eu3+ doped Sc2(MoO4)3 were prepared at 900 °C, and no concentration quenching luminescence were observed in Sc2(MoO4)3: x mol% Eu3+ phosphors though crystalline phase varied. In particular, the 10 mol% Eu3+-doped Sc2(MoO4)3 exhibited thermal enhancing luminescence (TEL) when excited with 277 nm light. At 125 °C, the intensity reached 250 % of the initial value, while at 300 °C, it remained at approximately 190 % of the initial intensity. With 396 nm excitation, the phosphor presented thermal quenching luminescence (TQL). In the TEL Sc2(MoO4)3: x mol% Eu3+ phosphors, the optimal temperature of TEL enhanced with Eu3+ concentration increasing. For the Eu2(MoO4)3 phosphor, it only demonstrated TQL with 277 nm and 396 nm excitations. The mechanism of TEL can be ascribed to the enhancement in structural rigidity resulting from the negative thermal expansion (NTE), which was accompanied by efficient energy transfer from MoO42− to Eu3+. Furthermore, the fluorescence lifetime of the 5D0 level demonstrated a declining trend then a rising trend with elevated Eu3+ concentrations, whereas the color purity value exhibited an ascending trend always.