Synthesis and characterization of α-SnWO₄ powders obtained by microwave-assisted hydrothermal method

Abstract

The structural, morphological, and optical properties of α-SnWO₄ synthesized by microwave-assisted hydrothermal method at 150 °C for different times were investigated. XRD revealed the formation of the orthorhombic phase, without the presence of a secondary phase. The sample processed for 64 min showed a reduction in unit cell volume, suggesting a decrease in the structural defects present in the sample. The Raman spectroscopy confirmed the formation of α-SnWO₄, with the presence of vibrational modes attributed to the [WO₆] octahedron. FE-SEM images revealed the formation of agglomerate nanosheets in all samples. The band gap (E_gap) of the samples presented values in the range from 1.58 to 1.70 eV. The increase in E_gap value of the sample processed for 64 min corroborated the decrease in the structural defects suggested by the Rietveld refinement. Finally, the photoluminescence was measured, with maximum emission in the blue region of the electromagnetic spectrum around 454 nm, which was attributed to the [WO₆] octahedron.

Keywords:
α-SnWO₄; photoluminescence; synthesis; Rietveld refinement