Dielectric properties of the sintered nano- and micro-sized fresnoite without/with strontium titanate phase

Within the BaO–SrO–TiO2–SiO2 system, fresnoite (Ba2TiSi2O8) was prepared as a major phase using conventional sintering routes through solid-state reaction. Strontium titanate (SrTiO3) phase was observed at the highest strontium oxide containing sample. The microstructure shows rounded to sub-rounded clusters of nano-fresnoite crystals in free- and low-SrO-containing samples, whereas, microscale of clear cubic and tetragonal crystals of both phases with some acicular strontium titanate were developed in-between. The value of dielectric constant was 6.48 for SrO-free sample, however, incorporation of SrO and its increase in the samples increases the dielectric constant to 120.39 (at 1 kHz and room temperature) in the sample containing the highest value of SrTiO3 phase. Accordingly the studied Sr-containing fresnoite composite materials can be considered as candidates for application in electronic devices for energy storage.