Correlation of the microstructure and microwave properties of Ba0.6Sr0.4TiO3 thick-films

Abstract The influence of the microstructure of screen-printed Ba 0.6 Sr 0.4 TiO 3 ceramic thick-films on their microwave properties has been investigated. The Ba 0.6 Sr 0.4 TiO 3 powders were synthesized through a sol–gel route. The spray-dried precursors were calcined at different temperatures. Scanning electron microscopy images and BET measurements revealed the primary particle size of calcined powder depending on the calcination temperature. The Ba 0.6 Sr 0.4 TiO 3 thick-films showed different microstructure after sintering due to the use of two different calcined BST powders as well as varying the sintering conditions. Permittivity, dielectric loss and tunability of thick-films were characterized with coplanar waveguide structures up to 40 GHz. A correlation of microstructure and microwave properties of the thick-films has been observed. Particularly the tunability could be improved by an optimized microstructure.