Effect of Pr on the Microstructure and Electrical Properties of Ta-Doped TiO₂ Capacitor-Varistor Ceramics

Abstract:

TiO₂ varistors doped with 0.1 mol% Ta and different concentrations of Pr³⁺ were obtained by ceramic sintering processing at 1400 °C and their properties were characterized by XRD, SEM, I-V and impedance spectroscopy. The effect of Pr on the microstructure, nonlinear electrical behavior and dielectric properties of the Ta-doped TiO₂ ceramics were investigated. It is found that Pr affects the grain size, electrical properties and the dielectric properties of the TiO₂-based varistors. The samples have the nonlinear coefficients (α) values of (3.0-5.0) with low breakdown voltages (4-30 V/mm). A small quantities of Pr can improve the nonlinear properties of the samples significantly. It was found that an optimal doping composition of 0.5 mol% Pr³⁺ leads to a low breakdown voltage of 9.2 V/mm, a high nonlinear constant of 4.9 and an ultrahigh electrical permittivity of 8.38×10⁴ (at 1 kHz), which is consistent with the highest grain boundary barriers of the ceramics. In view of these electrical characteristics, the TiO₂-0.5 mol% Pr³⁺ ceramic is a viable candidate for capacitor-varistor functional devices. The defects theory was introduced to explain the nonlinear electrical behavior of Pr-doped TiO₂ ceramics.

• Periodical: Materials Science Forum (Volume 687)
• Pages: 34-38
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.687.34
• Online since: June 2011
• Authors: Tian Guo Wang, Qun Qin, Dong Jian Zhou
• Keywords: Electrical Properties, Microstructure, Titanium Oxide, Varistor

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