The samples used in this study were prepared by conventional solid-state reaction technique. The starting materials were reagent grade BaCO3, ZnO and TiO2. The powders were weighed according to non-stoichiometric ratio of BaO–nZnO–3TiO2 with n = 0.5, 0.6, 0.7 and 0.8. Initially, the mixtures of the powders were milled in plastic jars using deionized water and zirconia balls for 20 h. Then the milled mixtures were dried and calcined at 1000 °C for 2.5 h. Subsequently, with 5 wt% PVA solution as a binder, the calcined powders without grinding were pressed into cylindrical samples with 18 mm in diameter and 9 mm in thickness under a pressure of 250 kg/cm2. At last, these samples were sintered at 1160–1220 °C for 2 h.