First-principles study of defect energetics in titanium-doped alumina

作者：Katsuyuki Matsunaga, Atsutomo Nakamura, Takahisa Yamamoto, Yuichi Ikuhara · 发表于：Physical review. B, Condensed matter · 年份：2003 · DOI：10.1103/physrevb.68.214102 · 被引用次数：59 · 研究领域：Advanced ceramic materials synthesis、Nuclear materials and radiation effects、Ferroelectric and Piezoelectric Materials

First-principles plane-wave pseudopotential calculations were performed to study electronic structures, structural relaxation, and energetics of point defects in Ti-doped ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}.$ Substitutional and interstitial Ti ions with charge compensating intrinsic defects were considered, and their formation energies were evaluated under various atomic chemical potentials. It was found that substitutional ${\mathrm{Ti}}^{4+}$ ions with charge compensating Al vacancies were most stable in the oxidized condition. In contrast, as oxygen chemical potentials decreased, the formation energy of substitutional ${\mathrm{Ti}}^{3+}$ decreased to have the smallest value in the relatively reduced conditions. However, in the intermediate range of oxygen potentials, substitutional ${\mathrm{Ti}}^{3+}$ and ${\mathrm{Ti}}^{4+}$ exhibited similar formation energies, indicating that these Ti defects can coexist in a particular reduction environment.