Dielectric properties of barium strontium titanate / polybenzoxazine composite with 0-3 connectivity

Abstract

Barium strontium titanate (Ba1-xSrxTiO3) ceramic is a kind of favourable electronic material because of its high dielectric constant and alterable Curie temperature. Curie temperatre of Ba1-xSrxTiO3 can be adjusted to meet requirements of various applications by varying the strontium molar fraction (X). However, these ceramics require high temperature processing, which is not suitable in some applications, especially in embedded capactior. Polymer-ceramic composites are the candidate in this application. They combine superior properties of ceramic and polymer including high dielectric constant and low temperature processing. In this study, Ba1-xSrxTiO3 nano-powders were synthesized via slol-gel method followed by 2-step thermal decomposition. The Ba1-xSrxTiO3 ceramics (x = 0, 0.3, 0.5, and 0.7) were obtained by sintering at 1350 C for 2 h. The effect of the strontium molar fraction on microstructure and dielectric behaviours were investigated. For 0-3 connectivity composite. polybenzoxazine and sol-gel Ba0.7Sr0.3Sr0.3TiO3 powders were used as polymer matrix and ceramic fillers, respectively. The amount of ceramic fillers in polybenzoxazine matrix was from 30-80 wt% increment of 10 wt% in order to investigate effect of ceramic contents on dielectric behaviour of the composites. The dielectric behaviours of these composites were also measured as functions of frequencies (1 kHz-10 MHz) and temperatures (20 -130 C)