The color exhibited by tungsten trioxide (WO3) can be associated with both its stoichiometry and crystallinity. Correlation between the color exhibited by WO3 powders and their purity and crystalline properties is reported in this paper. The WO3 powders were deposited by evaporation of tungsten trioxide from the surface of a tungsten filament. The WO3 powders exhibited three different shades of blue: navy, royal, and sky. The color of the WO3 powders changed to white after thermal treatment at 500 °C for 30 min in an ambient atmosphere. Raman analyses showed that transition from amorphous to crystalline WO3 started when the powders exhibited navy-blue color and ended when WO3 powders exhibited a white color. Scanning electron microscopy analysis showed particle agglomeration characteristics in all WO3 powders, even after they were thermally treated. The mechanism of deposition of WO3 from the tungsten filament was suggested to be governed by thermal evaporation of tungsten trioxide from the surface of the oxidized tungsten filament.
The effect of plastic deformation on the optical and structural properties of ZnSe crystals has been investigated. The optical properties have been monitored by cathodoluminescence measurements as a function of the deformation degree. Remarkable differences in the defect related emissions from the most severely deformed areas have been encountered. Deformation of the crystal lattice of ZnSe, associated to slip phenomena, has been studied by means of Electron Backscattered Diffraction (EBSD) and micro-Raman spectroscopy. The relation between the deformation and the optical properties of the ZnSe crystals has been described.
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