Effect of Mg-doping on pyrolysis evolution and phase constitutes of Ba0.7Sr0.3TiO3 (BST) system derived from sol-gel

Gels and powders of dielectric Ba0.7Sr0.3(Ti1-xMgx)O-3 (BST) were prepared by sol-gel technique. Effect of Mg-doping of on the pyrolysis evolution and phase constitutes of BSTs was investigated using DSC-TG and XRD. Results show that Mg-doping leads to a remarkable change of crystallizing process of BSTs from a double phase-transformation of non-doping sample into a single phase-transformation and quickens the crystallizing reaction of formation of BST perovskite. The maximum Mg-doping level should be less than x= 0.15 in Ba0.7Sr0.3 (Ti1-xMgx)O-3 system. The amount of (Ba,Sr)CO3 phase in the BST powders increases considerably with the Mg-doping level, indicating Mg atoms should occupy the A positions of ABO(3) structure of BST, instead of the B position.