Impact of Molybdenum Doping on the Structural, Optical and Dielectric Properties of α-Al2−x MoxO3

Abstract

The effects of Molybdenum (Mo) doping on the structural, optical, and electrical properties of alumina α-Al2−xMoxO3, (x = 0.02–0.14) synthesized via solid-state reaction method have been studied. X-ray diffraction (XRD) analysis confirms of single-phase hexagonal corundum structure in the range 0.06–0.14. The influence of Mo doping on the structural parameters was estimated from XRD data by applying the Rietveld profile fitting method and Fourier-transform infrared spectroscopy. XRD results revealed that replacing Al with Mo does not affect the unit cell dimensions owing to that Mo occupy the vacant sites available in the crystal structure. The electron density map revealed strong positive peaks corresponding to the position occupied by (Al/Mo) and the intensity of these peaks increases with increasing Mo doping. Optical properties revealed that the energy bandgaps (Eg) increase with increasing MoO3, due to the difference in the ionic radius of Al+3 and Mo+3. The dielectric properties indicated that the values of ε′ and tan δ increased as molybdenum concentration increased as a result of the free charges build-up at the interfaces. It was found that tanδ peak lies in the region where DC-conductivity dominates which is a clear indication of the contribution of ionic conduction to the dielectric loss.