Dielectric properties of acceptor-doped SrTiO3 ceramics

0.5 atom % Ni-doped SrTiO3 was prepared by solid-state reaction route. Average grain sizes of un-doped and doped samples were 1.3 and 4.1. micron respectively. Relative permittivity of ST ceramics was found to increase with Ni-doping. Capacitance was measured at temperatures ranging from 400degrees to 700 degreesC in the frequency range 10 Hz to 13 MHz. Grain and grain boundaries relaxation frequencies were shifted to higher frequency with temperature. Impedance measurements were conducted at 400 degreesC to separate grain and grain-boundary contributions. Bulk and grain-boundary resistance were evaluated from impedance complex plain plot. Bulk resistance of doped and un-doped ST ceramics was more or less same. Single grain-boundary resistance of doped sample was higher than un-doped one, indicating GB resistance increases with acceptor doping.