Materials with high photoluminescence (PL) intensity can potentially be used in optical and electronic devices. Although the PL properties of bismuth(III) oxide with a monoclinic crystal structure (α-Bi2O3) have been explored in the past few years, methods of increasing PL emission intensity and information relating PL emission to structural defects are scarce. This research evaluated the effect of a pressure-assisted heat treatment (PAHT) on the PL properties of α-Bi2O3 with a needlelike morphology, which was synthesized via a microwave-assisted hydrothermal (MAH) method. PAHT caused an angular increase between the [BiO6]-[BiO6] clusters of α-Bi2O3, resulting in a significant increase in the PL emission intensity. The Raman and XPS spectra also showed that the α-Bi2O3 PL emissions in the low-energy region (below ∼2.1 eV) are attributed to oxygen vacancies that form defect donor states. The experimental results are in good agreement with first-principles total-energy calculations that were carried out within periodic density functional theory (DFT).

This paper describes the production of transparent hydrophobic polymeric films made of poly(vinyl chloride) and paraffin wax. A liquid polymeric solution was prepared and spray-deposited on silica glass and nonwoven fabric surfaces. The contact angle between water droplets and glass substrate was 102°while that between droplets and nonwoven fabric was 120°. The films exhibited hydrophobic behaviour regardless of the droplet size. Field emission gun scanning electron microscopy revealed complete adhesion of the film on the substrate and a film thickness of 0.16 µm. The atomic force microscopy micrographs showed a nanoscale rough film surface, which was responsible for air entrapment, preventing water from penetrating the film. This fact explains the high contact angle obtained. The raw materials also contributed to the film's hydrophobicity because of their non-polarity, which prevents miscibility between water droplets and film.

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