Synthesis, thermal expansion and optical properties of ZrV2O7 thin films

Cubic ZrV2O7 thin films have been synthesized by sol-gel spin-coating method. The influences of annealing temperatures on the phase composition and morphology of ZrV2O7 thin films were investigated using XRD, SEM, and EDX. Negative thermal expansion (NTE) and optical performances of cubic ZrV2O7 thin films were analyzed using variable temperature XRD and UV–Vis spectroscopy. Results indicate that as-deposited ZrV2O7 thin films have an amorphous structure with smooth and dense surface. Cubic ZrV2O7 thin films were prepared after heat treatment at 720 °C for 1 h. It was found that the thin films contained V2O5 impurity with the Zr: V = 1:2 precursor solution. Pure cubic ZrV2O7 thin films were fabricated with the Zr: V = 1.75:2 precursor solution. Cubic ZrV2O7 thin films show isotropic NTE in the temperature range of 100–700 °C. The coefficients of thermal expansion (CTEs) of ZrV2O7 films along the a, b, and c axes are −6.88 × 10−6 °C−1, and the volumetric and linear CTEs are −20.56 × 10−6 °C−1 and -6.85 × 10−6 °C−1, respectively. The transmittance of cubic ZrV2O7 thin film is approximately 80 %.