Microwave-assisted synthesis of W1−xMoxO3·0.33H2O compounds with enhanced band gap

Abstract

Optoelectronic solid solution powder materials with phase W1−xMoxO3·0.33H2O (where X = 0, 25, 50, 75 and 100 %), were synthetized using hydrothermal synthesis assisted by microwave heat radiation. The crystallographic phase was identified by X-ray diffraction and RAMAN techniques. The morphology was studied by means of electron microscopy techniques (SEM and TEM). Materials with X = 0, 25, 50 and 75 % were indexed with orthorhombic phase and material with X = 100 % was indexed with hexagonal phase (a combination of MoO3 and MoO3·0.55H2O phases). The band gap for each material (X = 0, 25, 50, 75 and 100 %) was determined using Kubelka–Munk theory and Tauc plots, being W0.25Mo0.75O3·0.33H2O (WM75m) the best compound with 1.90 eV. Because of the experimental results, it can be concluded that the band gap behavior is related with particle size and Mo percent content thus originating a decrease in parameter or axis “b” of the crystal lattice.