Effects of Mg addition and sintering temperatures on chemical compositions, microstructures, densities and dielectric properties of strontium titanate

Abstract

Increasing demands in dielectric capacitors for electronic applications require continuous improvement of dielectric materials in terms of enhanced dielectric constant and minimal dielectric loss. This study aimed at synthesizing strontium titanate powders doped with 10, 20, and 30at% of Mg, and examining relationships among additive concentrations, chemical compositions, sintering temperatures, microstructures, and dielectric properties of strontium titanate. Experimental findings indicated that increasing doping concentrations resulted in increased secondary phase content, MgO, which seemed to have consequently led to grain size reduction. However, MgO concentrations were found to be lower than 10wt%, which possibly have not significantly changed the sample׳s dielectric properties. The results also revealed that a higher sintering temperature has led to an increase in sample density as well as to an enhancement in dielectric constant. It was further observed that strontium titanate samples doped with 30at% Mg and sintered at 1330°C gave the highest dielectric constant value, which was ten times higher than the samples with 10at% Mg sintered at 1250°C, the sample with the lowest dielectric constant. All samples in the study though yielded dielectric losses of less than 3%, which are within the acceptable range for practical applications.