Crystal Structural Characteristics and Electrical Properties of (Ba 0.7 Sr 0.3- x Ca x )(Ti 0.9 Zr 0.1 )O 3 Ceramics Prepared Using the Citrate Gelation Method

The electrical properties of (Ba Sr Ca )(Ti Zr )O (0 ≤ ≤ 0.2) (BSCTZ) ceramics prepared using citrate gelation (CG) method were investigated by substituting Ca ions for the Sr sites based on the structural characteristics of the ceramics. BSCTZ was sintered for 3 h at 1300 °C, lower than the temperature (1550 °C) at which the specimens prepared using the solid-state reaction (SSR) method were sintered, which lasted for 6 h. As the amount of substituted Ca ions increased, the unit cell volume of the BSCTZ decreased because of the smaller ionic radius of the Ca ions compared to the Sr ions. The dielectric constant of BaTiO -based ceramics is imparted by factors such as the tetragonality and B-site bond valence of the ceramics. Although the ceramic tetragonality increased with Ca ion substitution, the = 0.05 specimens exhibited the highest dielectric constant. The decrease in the dielectric constant of the sintered > 0.05 specimens was attributed to the increase in the B-site bond valence of the ABO perovskite structure. Owing to the large number of grain boundaries, the breakdown voltage (6.6839 kV/mm) of the BSCTZ prepared using the CG method was significantly improved in relation to that (2.0043 kV/mm) of the specimen prepared using the SSR method.