Effects of Ta2O5 addition on properties of Ba0.6Sr0.4TiO3-Mg0.9Zn0.1O ceramics for phase shifter applications

Abstract

Influence of Ta2O5 addition on the dielectric properties of Ba0.6Sr0.4TiO3 (BST) mixed with 65 wt% Mg0.9Zn0.1O (MZO) composite was investigated. The XRD results indicate that the main phases in all Ta2O5 doped samples are BST and MZO. With increasing the amount of Ta2O5, the lattice constant of BST increases. The SEM morphology shows that the grain size of BST-MZO decreases with a certain amount of Ta2O5 addition. The dielectric constant decreases while loss tangent decreases first and then increases with increasing frequency. The dielectric constant, the tenability and loss tangent decrease with increasing addition of Ta2O5. Optimum doping amount of Ta2O5 reduces the loss tangent of BST-MZO compound which can also ensure the moderate dielectric constant and tenability. When Ta substituted 1.0wt%, the dielectric constant, the dielectric loss and the tenability are 85.2, 0.0005 (at 1MHZ) and 17% (under electric field 7kv/mm), respectively. At microwave frequency (4.025GHz), the dielectric constant decreases to 81.03 but the dielectric loss increases to 0.0049. This material shows good dielectric properties, which is one promising candidate for phase shifter applications.