Electrical and dielectric properties of colossal permittivity co-doped (Er,Pr, Ta) titanium dioxide

Abstract

The electrical and dielectric properties of titanium dioxide containing erbium and praseodymium oxides as acceptors, and tantalum oxide as donor dopants were investigated aiming to identify the effects of different dopants on the dielectric properties. Dense samples with 1 mol% total co-dopants were prepared by the solid-state synthesis method, followed by conventional sintering at 1450 ◦C. A secondary phase, Er2Ti2O7, was found in some of the prepared samples. Impedance spectroscopy spectra of the samples are similar, with an average activation energy for interface conduction of about 0.27 ± 0.05 eV, except for the sample with excess Ti, (Er0.5Ta0.5)0.01Ti1.09O2, (0.38 ± 0.05 eV). All samples exhibit colossal permittivity (>104) in wide temperature and frequency ranges. Erbium oxide was found to be more effective in increasing the electric permittivity of TiO2 than praseodymium oxide. Excess titanium leads to a larger grain size, and decreases both the permittivity and the dissipation factor of titanium dioxide.