Influence of Microstructure-Evolution Changes on the Dielectric Properties of Strontium Titanate Prepared via Mechanical Alloying
Asian Journal of Applied Sciences
SrTiO3 is a dielectric material of considerable interest. However, the relationships between microstructure and dielectric properties have not been studied in detail. Hence, we have undertaken an extensive experimental work to study the evolution of the dielectric properties against morphological changes of SrTiO3. SrTiO3 was prepared using the mechanical alloying method and samples with nano-sized starting powder were obtained. The milled powder was pressed into pellets and sintered at various
... sintered at various temperatures ranging from 500 °C to 1400 °C. XRD studies showed that these ceramics completely formed a perovskite phase at 900 °C. FeSEM studies show the presence of small grain sizes ranging from 120 to 600 nm. Dielectric constant (εr') and dielectric loss tangent (tan δ) were measured as a function of frequency and correlated with the microstructure. εr' and tan δ against frequency show a falling trend at the lower frequency region due to the changing interfacial effect. For sintering temperatures 1000 °C to 1100 °C, grain size and XRD peak data show a significant increase with the corresponding increase in εr', suggesting a sudden increase in the polarizability due to significant increase in crystallinity. With increasing sintering temperature, εr' increased proportionally with XRD peak and grain size increases, further confirming polarizability and crystallinity relationship. tan δ correlation with microstructure does not have a common trend.