Micro-structural, thermal, and optical properties of nanostructured CaMoO4 materials screened under different processes

In this work, we have varied numerous conditions to obtain nanocrystalline CaMoO4 materials by high-energy -ball-milling, mechanical stirring, and wet chemical methods. Despite several conditions suited for the formation of scheelite CaMoO4 phase, interestingly mechanical stirring of CaCO3 and MoO3 precursors with deionized water yielded pure tetragonal CaMoO4 phase in a simple way. All the processed CaMoO4 materials show rather broad reflections with reduced average crystalline size (14.2 similar to 26.6 nm). The thermal profiles of phase pure CaMoO4 materials show relatively low weight loss as compared to contaminated samples signifying the for-mation of the CaMoO4 phase. The calculated optical band gap for the CaMoO4 samples is in the range of 3.55-3.93 eV. While the high-energy-ball-milling method prepared CaMoO4 materials exhibit lower NIR reflectance values, the wet chemical synthesized CaMoO4 materials reveal quite higher NIR reflectance in the region (750-2500 nm). The Raman spectral analyses well support the optical properties of the CaMoO4 phase. Agglomerated nature of round-shaped particles is seen for the co-precipitation and ball-milled processed CaMoO4 materials.

Automated summary

Different methods, including high-energy ball milling, mechanical stirring, and wet chemical methods, were employed to obtain nanocrystalline CaMoO4 materials. Interestingly, pure tetragonal CaMoO4 phase could be easily obtained through mechanical stirring of CaCO3 and MoO3 precursors with deionized water. The processed CaMoO4 materials showed reduced average crystalline size and relatively low weight loss compared to contaminated samples. The optical properties of the CaMoO4 phase were supported by Raman spectral analyses. The morphology of the processed CaMoO4 materials exhibited agglomerated round-shaped particles.