Novel phosphor GdY₂SbO₇ co-dope with Eu³⁺ and Bi³⁺ for optical thermometer

A series of GdY₂SbO₇:Bi³⁺, Eu³⁺ phosphors were prepared using the conventional solid-state reaction. In this study, the photoluminescence properties and temperature sensitivity of the samples were investigated. When Bi³⁺ and Eu³⁺ were codoped into GdY₂SbO₇, the intensity of Bi³⁺ decreased with increasing Eu³⁺ concentration, indicating a potential energy transfer from Bi³⁺ to Eu³⁺. To examine the temperature sensitivity of the sample, its emission spectrum was investigated in the range of 300-500 K. Based on different temperature dependences of Bi³⁺ and Eu³⁺, the relative sensitivity (S_r) and absolute sensitivity (S_a) of the samples were calculated using the fluorescence intensity ratio (FIR) and thermochromic methods. In FIR modes, S_r based on I_Eu³⁺/I_Bi³⁺ reached 1.26 % K^-1 at 500 K, while S_r on double excitation method reached 1.36 % K^-1 at 340 K. In addition, according to the thermochromic properties of GdY₂SbO₇:Bi³⁺, Eu³⁺ phosphor, the temperature-sensing ability of the sample was investigated, and S_r reached a maximum value of 0.5996 % K^-1 at 300 K.