Mechanochemical Synthesis and Temperature-Dependent Optical Properties of Thermochromic (Ag_1-x Cu_x )₂ HgI₄

Thermochromic materials are generally synthesized via high-temperature melting reaction or solution-based synthesis. Herein, all-inorganic thermochromic compounds of (Ag_1-x Cu_x )₂ HgI₄ were synthesized by solvent-free simple and scalable mechanochemical grinding at room temperature. Temperature-dependent electronic absorption spectroscopy along with DSC analysis confirmed the thermochromic events within these materials, and the phase transition temperature varied with solid solution compositions. The photoluminescence (PL) spectra is red-shifted with the increase in the Cu content in (Ag_1-x Cu_x )₂ HgI₄ (x=0-1).