Dielectric relaxation properties of SrTiO₃ ceramics modulated by stoichiometry

SrTiO₃ has received increasing attention duo to the fact that small perturbation can produce outstanding physical properties. Nonstoichiometric SrTiO₃ ceramics have been prepared in the range of Sr/Ti = 1.064–0.943. Their dielectric behaviors are investigated in the temperature range of 30–500 °C and in the frequency range 100 Hz to 2 MHz. It is observed that the two types of dielectric relaxation processes are caused by polar nanoregions associated with Sr non-stoichiometry and variable range hopping behavior associated with the dipolar effects for Sr/Ti>1 and Sr/Ti<1 ceramics samples, respectively. Our findings imply that the cation vacancy may be responsible for the adjusted properties in nonstoichiometric SrTiO₃.