Enhanced dielectric loss of Mg doped Ba0.7Sr0.3TiO3 ceramics

The effect of MgO doping on the structural, microstructural and dielectric properties of Ba0.7Sr0.3TiO3 (BST) ceramic from the point of view of its application in microwave tunable devices has been studied. All the samples crystallize into perovskite structure. There is significant reduction in the value of loss factor with the increase in Mg-level, the dielectric constant and tunability are also reduced with the increase in Mg-level. Interestingly, the Fig. of merit of the material is found to be enhanced with increase of Mg-doping. The observed dielectric properties are explained on the basis of defect chemistry involved when Mg is doped in Ba0.7Sr0.3TiO3 ceramics. The effect of dc field on the dielectric constant and the dielectric breakdown strength of the paraelectric phase Mg doped BST ceramic samples are also studied.