Modified Phase Diagram for the Barium Oxide–Titanium Dioxide System for the Ferroelectric Barium Titanate |
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| Authors: | Soonil Lee Clive A. Randall Zi-Kui Liu |
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| Affiliation: | Center for Dielectric Studies, Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802; Phase Research Laboratory, Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 |
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| Abstract: | The ferroelectric phase transition behavior in BaTiO3 was investigated for various annealing times, temperatures, and Ba/Ti ratios by means of a differential scanning calorimeter. Coupling these observations with powder X-ray diffraction and transmission electron microscopy allowed new insights into the barium oxide (BaO)–titanium dioxide (TiO2) phase diagram. The transition temperature was varied systematically with the Ba/Ti ratio at annealing temperatures from 1200° to 1400°C in air. The transition temperature decreased with increasing concentrations of BaO and TiO2 partial Schottky defects, and showed a discontinuous change at the phase boundaries. Beyond the solubility region, two peritectoid reactions were confirmed and revised; first around 1150°C for Ba1.054Ti0.946O2.946→Ba2TiO4+BaTiO3 and second 1250°C for BaTi2O5→Ba6Ti17O40+BaTiO3, respectively. All other regimes of the BaO–TiO2 were found to be consistent with the reported diagrams in the literature. |
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