Thermal enhancement of 2H11/2 → 4I15/2 up-conversion luminescence of BaLu6(Si2O7)2(Si3O10):Er3+/Yb3+ phosphors

A series of BaLu6(Si2O7)(2)(Si3O10):Er3+/Yb3+ phosphors were manufactured by high temperature solid phase reaction method. The X-ray diffraction (XRD) and vary temperature up-conversion luminescence (UCL) under 980 nm laser excitation were measured to analyze the structure and optical thermal behaviors. When the fixed Er3+ concentration is 0.1, the brightest sample appears at Yb3+ concentration 3.0. By adjusting the doping concentration of Er3+ and Yb3+ respectively, the thermal enhancement UCL times of H-2(11/2)-> I-4(15/2) transitions of Er3+ attain the maximum point while Er3+/Yb3+ is 0.01/3.0. And the thermal enhancement UCL of H-2(11/2)-> I-4(15/2) transitions of Er3+ is 4.12 times, and the total green luminescence intensity increases 1.97 times at the range of 303-723 K. Additionally, based on fluorescence intensity ratio (FIR) technique, the maximum absolute sensitivity is 0.00645 K-1. The single doped 1.0Er(3+) sample has the thermal enhancement UCL of H-2(11/2)-> I-4(15/2) transitions of Er3+, however the single doped 4.0Er(3+) sample does not have, and this indicates that the cross relaxation between Er3+ is unfavorable to thermal enhancement of H-2(11/2)-> I-4(15/2). The possible vary temperature UCL mechanism was expound. The results manifest that the BaLu2.99Er0.01Yb3.0(Si2O7)(2)(Si3O10) phosphor can be a good candidate for optical thermometer at high temperature.