Electrical Properties of Nb-, Ga-, and Y-Substituted Nanocrystalline Anatase TiO2 Prepared by Hydrothermal Synthesis

Nanocrystalline anatase titanium dioxide powders were produced by a hydrothermal synthesis route in pure form and substituted with trivalent Ga3+ and Y3+ or pentavalent Nb5+ with the intention of creating acceptor or donor states, respectively. The electrical conductivity of each powder was measured using the powder-solution-composite (PSC) method. The conductivity increased with the addition of Nb5+ from 3 similar to x similar to 10-3 similar to S/cm to 10 similar to x similar to 10-3 similar to S/cm in as-prepared powders, and from 0.3 similar to x similar to 10-3 similar to S/cm to 0.9 similar to x similar to 10-3 similar to S/cm in heat-treated powders (520 degrees C, 1 similar to h). In contrast, substitution with Ga3+ and Y3+ had no measureable effect on the material's conductivity. The lack of change with the addition of Ga3+ and Y3+, and relatively small increase upon Nb5+ addition is attributed to ionic compensation owing to the highly oxidizing nature of hydrothermal synthesis.