Effect of molybdenum on structural, optical and microwave dielectric properties of copper tungstate

This article covers the structural and the optical properties of CuMo x W 1− x O 4 ceramics for x = 0, 0.02, 0.04, 0.06 and 0.08 prepared by solid-state reaction route. Chemical composition and microstructure of the prepared CuMo x W 1− x O 4 ceramic samples were characterized by means of X-ray diffraction, scanning electron microscopy, UV–Vis spectrophotometry and FT-IR spectroscopy. X-ray diffraction analysis confirmed the formation of monophasic wolframite structure whose cell volume is increased with increased Mo content. The Reitveld refinement of X-ray powder revealed the triclinic structure with P 1 ¯ symmetry. A reduction in optical band gap from 2.4 to 2.0 eV is obtained with increased Mo concentration. This reduction in band gap suggested its possible utilization in the visible region of electromagnetic spectrum. The photoluminescence (PL) peaks are shifted towards lower energy. The microwave dielectric parameters were measured by the Hakki–Coleman method. The dielectric constant ( ε ′) and dielectric loss (tan δ ) decreased from 17.049 to 12.375 and 0.0156 to 0.0129, respectively, with the increase in Mo content.