Energy transfer in Bi3+-Sm3+ co-doped phosphors for temperature sensing and imaging
Xue Yu, Yuqi Chen, Qinan Mao, Yang Ding, Gongxun Bai, Liang Chu, Meijiao Liu, Jiasong Zhong
Abstract
Fluorescence thermometry has the distinct superiority of non-invasive, non-contact, and high spatial resolution. However, the simultaneous improvement of temperature sensitivity and resolution remains challenging. Herein, the La3Ta0.8Sb0.2O7 matrix was co-doped by Bi3+ and Sm3+ with energy transfer for tunable emission color, which was further applied for fluorescence temperature sensing and imaging. With the partial substitution of Sb5+ with Ta5+, the emission peak of La3SbO7:0.04Bi3+ shifted from 530 nm to 460 nm, together with a 2.1-fold enhancement of emission intensity. The emission could be shifted from bright blue to purple under 365 nm excitation based on the energy transfer. The energy transfer efficiency from Bi3+ to Sm3+ can reach 41.6% via dipole–dipole interaction. The La3Ta0.8Sb0.2O7:(0.04Bi3+,0.005Sm3+) phosphors exhibit maximum relative sensitivity (Sr) of 1.32%K-1 (@498 K) and absolute sensitivity (Sa) of 0.059K-1 (@417 K), which have excellent temperature resolution and repeatability. Thus, the energy transfer in co-coped phosphors can simultaneously improve the temperature sensitivity and resolution for fluorescence temperature sensing. Besides, the phosphor/PDMS films can exhibit obvious thermochromic imaging.