Temperature stability of Zn2SnO4-doped BaTiO3 ceramics

Zn2SnO4-doped BaTiO3 ceramics were prepared as dielectric material though a conventional solid state reaction method. The room temperature dielectric constant was improved by Zn2SnO4 doping, with the appearance of diffuse phase transition and reduced dielectric loss. More importantly, the temperature stability of BaTiO3 ceramics (ΔC/C25°C) was modified by varying doping contents. The temperature dependence of sample with 2% doping contents satisfied the Electronic Industries Alliance Y5V temperature characteristic specification and was near the X7R specification. The SEM micrographs indicate that the BaTiO3 solid solution has a homogeneous fine-grained microstructure with grain size < 1 μm and X-ray diffraction pattern suggest that the sample with 2% Zn2SnO4 doping contents have a tetragonal phase at RT. DPT was resulted from element substitution of Ti4+ with Sn4+, as lattice parameters increasing under inter-grain stress. Results of impedance spectroscopic analysis suggest the presence of two relaxation mechanisms. One was originated from the dipolar polarization in the grain, and the other was related with the hopping charge carriers of oxygen vacancy in the grain boundary. The dielectric loss over a wide temperature range was modified by the activation energies of the two type relaxation mechanisms.