Characterization and photoluminescence properties of ultrafine copper molybdate (α-CuMoO₄) powders prepared via a combustion-like process

We report a simple method for preparing copper(II) molybdate (CuMoO₄) powders via a combustion-like process. A gel was first prepared by the polymerizable complex method, where citric acid was used as a complexing and polymerizing agent and nitric acid was used as an oxidizing agent. The thermal decomposition behavior of the (CuMo)-precursor gel was studied by thermogravimetry–differential thermal analysis (TG–DTA), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). We observed that the crystallization of CuMoO₄ powder was completed at 450°C. The obtained homogeneous powder was composed of grains with sizes in the range from 150 to 500 nm and exhibited a specific surface area of approximately 5 m²/g. The average grain size increased with increasing annealing temperature. The as-prepared CuMoO₄ crystals showed a strong green photoluminescence emission at room temperature under excitation at 290 nm, which we mainly interpreted on the basis of the Jahn-Teller effect on [MoO₄^2- ] complex anions. We also observed that the photoluminescence intensity increased with increasing crystallite size.