Controllable-permittivity and low-loss of Ba0.5Sr0.5TiO3/MgO composites prepared by citrate gel derived core-shell powders

Abstract

Core-shell Ba0.5Sr0.5TiO3(BST)/MgO nano-composites have been synthesized by using an oleic acid modified citrate gel in situ process. The nano-composites exhibit a spherical microstructure consisting of large amounts of small particles with average sizes of 50-100 nm, which results in high F center levels in the composite ceramics. Interestingly, microwave permittivity of the composite can be reduced significantly with increasing volume fraction of MgO, while microwave loss and tunability remain almost unchanged, which is in good agreement with the results of the columnar model.