Rb2incl5·H2o Doped with Te4+ for Fluorescence Thermometry and Coordinated Water-Related Structural Phase Transformation

Zero-dimensional metal halides are extensively studied for their excellent optical properties due to the introduction of ns2 electrons. Here, we synthesized Rb2InCl5·H2O: x Te4+ with the coprecipitation method at room temperature, which converts the originally non-luminous Rb2InCl5·H2O into orange emission with a luminescence peak at 648 nm and a full width at half maximum of 142 nm (420.3 meV). The PL lifetime of Te4+-doped In-based metal halide Rb2InCl5·H2O exhibits a strong temperature dependence, and it possesses a maximum absolute sensitivity (SA) and relative sensitivity (SR) of 12×10-3 K-1 and 3.5% at 300 K, respectively, showing its capability for non-contact remote temperature measurement. Additionally, we capture the dynamic changes of coordinated water with temperature in Rb2InCl5·H2O for the first time, analyze the resulting structural transformation associated with coordinated water, and investigate the reversibility of this phase transition through cooling experiments in vacuum and air environments.