1) Duy Tan University 2) Institute of Materials Science, VAST 3) Thai Nguyen University 4) Hue Science University
Ba1−xCaxTiO3 samples (x = 0.0–0.30) were prepared by a solid state reaction method. X-ray diffraction patterns of the prepared samples show that the samples containing Ca2+concentration lower than 14 at% were identified to tetragonal phase of BaTiO3. In the samples with Ca2+ concentration higher than 14 at% CaTiO3 appears and coexists with BaTiO3. The dielectric constant at room temperature of all the samples was measured in a frequency range from zero to 2.5 MHz. A modified Cole-Cole formula was used to fit the experimental data. The fitting results show that the samples exhibit a single relaxation process that suggests BaTiO3 and CaTiO3 coexist in a nested hybrid form in the samples with Ca concentration in a range of (0.14–0.30). An abnormal dependence on the Ca2+concentration of the dielectric relaxation time was observed and supposed to be related with a pinning effect due to the local point-deformation caused by Ca2+ substitution and/or with a nesting of BaTiO3 and CaTiO3 in a hybrid form.