Characterization and electrical properties of tausonite (SrTiO_3) in nano ceramic composites

摘要

Tausonite phase was crystallized in SrTiO3 ceramic/borosilicate glass composite upon heat treatment at 1000-1100 degrees C range. Four samples containing 100/0, 90/10, 70/30 and 50/50 ratios from SrTiO3 ceramic/borosilicate glass were prepared. XRD, SEM/EDX, HR-TEM, SAED, ac conductivity (sigma(ac)), dielectric constant (epsilon '), porosity and bulk density were measured. The sintering process permits the precipitation of tausonite phase solely in case of SrTiO3 ceramic ratio between 100 and 70%; whereas, rutile and cristobalite were developed in case of equal ratios of SrTiO3 ceramic and borosilicate glass. Investigating the microcrystalline structure revealed the spread of cubic tausonite crystals in micro- and nano-scale size in the samples containing 100, 90 and 70% SrTiO3 ceramic. The decrease of SrTiO3 content to 50% led to formation tetragonal crystals of both rutile and cristobalite phases. The dielectric constant and ac conductivity of the samples have been studied in the temperature range from room temperature up to 300 degrees C. The activation energy attained values between 0.12 and 0.74 eV. The sample with the highest percentage of SrTiO3 phase (100 wt%) exhibited the utmost dielectric constant and that with 30 wt% glass fraction showed dielectric constant mainly temperature independent, which permits its application in electronic devices in wide range of temperatures.