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

Abstract

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 ∼ 26.6 nm). The thermal profiles of phase pure CaMoO4 materials show relatively low weight loss as compared to contaminated samples signifying the formation 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.

Keywords

• Scheelite phase
• CaMoO4
• Processing
• Characterization
• Properties