Precise Temperature Sensing and Optical Information Storage via Dual-Emission Gallate Phosphors

Luminescent temperature sensing has become a research hotspot in the past few years. Nevertheless, improving the sensitivity and resolution remains a key challenge. Herein, Bi3+,Sm3+-codoped CaYGaO4 phosphors with precise temperature sensing performance and excellent photochromic characteristics were developed. The energy difference between the Sm3+ levels hinders the multiphoton relaxation (MPR) process, giving rise to temperature insensitivity. By virtue of the drastically different temperature dependence between Bi3+ and Sm3+ ions, an accurate fluorescence intensity ratio (FIR) thermometer is fabricated. Sm3+ emission is used as a reference signal, while Bi3+ emission is adopted as a probe signal. The maximum absolute sensitivity (Sa) and relative sensitivity (Sr) of the CaYGaO4:Bi3+,Sm3+ phosphors are 0.0018 K–1 (@563 K) and 0.56% K–1 (@544 K), respectively. Moreover, the CaYGaO4:Bi3+,Sm3+ exhibits superior photochromic characteristics, rapidly changing its color from white to brown in 25 s under 254 nm light irradiation, and has outstanding cycling stability. Overall, the phosphors provide potential multifunctional applications in anticounterfeiting and optical information storage fields.