Role of cadmium on the phase transitions and electrical properties of BaTiO3 ceramics

The search for high piezoelectric and electromechanical properties near morphotropic phase boundaries (MPB) in lead-free ceramics has attracted considerable interest. The MPB can be obtained in the composition-temperature phase diagram by combining stabilized rhombohedral (R) and tetragonal (T) ends, which possess cubic (C) to R or C to T transitions, respectively. The R-end is usually realized by doping ions Zr4+, Hf4+ or Sn4+ at the Ti4+ site, whereas the T-end can be generated by Ca2+ doped at the Ba2+ site of BaTiO3. Our recent computational work (Phys. Rev. B. 93, 144111, 2016) showed that Cd2+ doped BaTiO3 can be considered as a potential T-end. In the present study, we synthesized (Ba1−xCdx)TiO3 ceramics to investigate the effects of Cd2+ on the phase transition, dielectric, ferroelectric and piezoelectric properties of the ceramics. Although our results show that Cd2+ fails to stabilize the T phase, i.e., the transition temperatures vary little with Cd2+ concentration, the electrical properties are found to be optimized for Cd2+% of 5%. The optimization of the properties is related to the microstructural features including grain size and sample density.