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.