Structural phase transition and thermochromic behavior of synthesized W-substituted CuMoO4

Tungsten (W)-substituted copper molybdenum oxide (CuMoO4) compounds with different substitution ratios of W were synthesized, and the effects of the substitution ratio on the structural phase transition and thermochromic behavior were investigated. Precursor powders prepared by a liquid-phase method were heat-treated at 550–600 °C for 24 h to obtain CuMo1−xWxO4 (x=0.04–0.12) powders. Differential scanning calorimetry (DSC) revealed that the temperature at which CuMo1−xWxO4 (x=0.04–0.12) underwent a structural phase transition of the γ phase to the α phase increased with increasing x. CuMo1−xWxO4 (x=0.06) underwent a structural phase transition in the range of RT to 100 °C and showed a significant change in the diffuse reflectance spectrum in the visible light range, suggesting that the color of the CuMo1−xWxO4 (x=0.06) powder changed visually in the range of RT to 100 °C. The thermal change in color of the CuMo1−xWxO4 (x=0.06) powder was recognized even after 10 times repetition of heating and cooling.