In situ synthesis of Ba0.5Sr0.5TiO3–Mg3B2O6 composites and their dielectric response

Ba0.5Sr0.5TiO3–Mg3B2O6 (BST–MB) composites have been prepared in situ by a citrate gel process, and their structure and effective dielectric response have been investigated. The precursor with pH≥7 is suitable for in situ formation of the diphase structure consisting of BST and MB. Accordingly, MB particles homogeneously disperse in BST particles, accompanied by the formation of boron-rich grain boundary resulting from liquid phases sintering of B2O3. Related with the existence of boron-rich grain boundary and the incorporation of Mg2+ into BST lattice, permittivity decreases rapidly with increasing volume fraction of MB from 0.0 to 0.2 and then decreases slowly with further increasing, which coincides with theoretical prediction of the layered model.