Investigation on the dielectric properties of Mg-doped (Ba0.95Ca0.05)(Ti0.85Zr0.15)O3 ceramics

Mg-doped Ba0.95Ca0.05Ti0.85Zr0.15O3 ceramics were prepared through a solid-state reaction method and their dielectric relaxation behavior was investigated. All of compositions exhibit perovskite strucutre with acceptor-Mg in the B-sites. The grain size was reduced and homogenized by Mg doping. The Tc and the magnitude of diffusion change regularly in the studied compositional ranges. The relaxor diffuseness from ferroelectric phase transition reached maximum at x=0.01. The impedance study showed that the conductance activation energy of grain (Ea-g) is higher than that of grain-boundary (Ea-gb). And Ea-gb varies with Mg concentrations, which is more stable than Ea-g. These results were explained by oxygen vacancies generated and gathered as cluster rotate around the MgTi″ in the grains.