This is because the BaTiO3 products at 100 °C had some lattice defects such as OH groups as found in the TGA results ( Fig. 2). Both lattice parameters of a and c decreased with increasing process temperature ( Fig. 3). The c/a value increased from 1.000 at 100 °C to 1.005 at 200 °C, indicating the possible formation of tetragonal BaTiO3 at higher process temperatures although the c/a value was smaller than for pure tetragonal.