Xiang Xin, Zhang Guikai, Wang Xiaolin, Tang Tao, Shi Yan
Institute of Materials, China Academy of Engineering Physics, 621907, Jiangyou, China.
Phys Chem Chem Phys. 2015 Nov 21;17(43):29134-41. doi: 10.1039/c5cp04867b.
First-principles plane-wave pseudopotential calculations have been performed to study the charge states and energetics of intrinsic point defects as vacancies, interstitials and antisite atoms in α-Al2O3, and thus a new perspective on the process of intrinsic point defects has been proposed. Considering the various charge states for each intrinsic point defects, V(Al)(3-), V(O)(0), Al(i)(3+), O(i)(2-), Al(O)(3+), and O(Al)(3-), not all in their fully ionized states are found to be most stable and in pure Al2O3. From the formation energies of individual point defects, the antisite atom O(Al) will be readily formed in α-Al2O3 in an O-rich environment. By combination of charge states and formation energies, the defect types of Schottky, Al Frenkel and antisite pairs formed are found to be dependent on the O condition, and the most stable Schottky defect type is not the commonly considered {3V(O)(2+):2V(Al)(3-)}. There are two types of possible O Frenkel defects under both O conditions, yet the most stable defect is {O(i)(1+):V(O)(1-)} rather than the commonly believed {O(i)(2+):V(O)(2-)}. The bizarre configuration and the charge state of Schottky and Frenkel defects predicated in this work provide a new perspective on the process of intrinsic point defects in α-Al2O3.
已进行第一性原理平面波赝势计算，以研究α-Al2O3中本征点缺陷（如空位、间隙原子和反位原子）的电荷态和能量学，从而提出了关于本征点缺陷形成过程的新观点。考虑到每个本征点缺陷的各种电荷态，即V(Al)(3-)、V(O)(0)、Al(i)(3+)、O(i)(2-)、Al(O)(3+)和O(Al)(3-)，发现并非所有处于完全电离状态的缺陷在纯Al2O3中都是最稳定的。根据单个点缺陷的形成能，在富氧环境中，α-Al2O3中容易形成反位原子O(Al)。通过结合电荷态和形成能，发现形成的肖特基缺陷、Al弗伦克尔缺陷和反位原子对的缺陷类型取决于氧条件，并且最稳定的肖特基缺陷类型不是通常认为的{3V(O)(2+):2V(Al)(3-)}。在两种氧条件下都存在两种可能的O弗伦克尔缺陷类型，但最稳定的缺陷是{O(i)(1+):V(O)(1-)}，而不是通常认为的{O(i)(2+):V(O)(2-)}。这项工作中预测的肖特基缺陷和弗伦克尔缺陷的奇异构型和电荷态为α-Al2O3中本征点缺陷的形成过程提供了新的视角。
