Photoconductive TiO[sub.2] Dielectrics Prepared by Plasma Spraying

• Published in: Applied sciences Vol. 14; no. 5
• Main Authors: Ctibor, Pavel, Straka, Libor
• Format: Journal Article
• Language: English
• Published: MDPI AG 01-02-2024
• Subjects: Coatings; Dielectrics; Plasma physics; Powders; Czech Republic; Germany
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app14051714

Titanium dioxide coatings (TiO[sub.2]) were sprayed using a water-stabilized plasma gun (WSP) to form robust self-supporting bodies with the character of a ceramic disc capacitor (CDC). Agglomerated nanometric powder was used as feedstock. Argon was applied for powder feeding as well as coating–cooling to minimize the influence of ambient air. Stainless steel was used as a substrate, and the coatings were released after cooling. A more than three-millimeter-thick self-supporting TiO[sub.2] plate was observed using HR-TEM and SEM. Porosity was studied by image analysis on polished sections. Thermal post-treatment on the coating was conducted at a rather low temperature of 500 °C. The results of the subsequent dielectric measurement showed high permittivity, but this was strongly frequency-dependent and accompanied by a progressively decreasing loss tangent. On the other hand, the plasma-sprayed TiO[sub.2] exhibited persistent DC photoconductivity under and after illumination with a standard bulb.