Effects of Sr/Ti ratio on the microstructure and energy storage properties of nonstoichiometric SrTiO3 ceramics

Effects of nonstoichiometric SrTiO3 ceramics have been investigated in the range of Sr/Ti=0.994-1.004. A cubic perovskite structure is maintained at all compositions without any secondary phase. Grain size increases at the beginning and then decreases with increasing Sr/Ti ratio. The highest breakdown strength and energy density are obtained at Sr/Ti=0.996, 283 kV/cm and 1.21 J/cm(3), respectively, which are higher than that of stoichiometric SrTiO3 ceramic (210 kV/cm of breakdown strength, 0.7 J/cm(3) of energy density). Sr/Ti > 1 ST ceramics are prone to semi-conductivity process. Among them, the ST ceramic at Sr/Ti=1.004 has the highest permittivity, 2455. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.