Lerch D, Dössel K, Hammer L, Müller S
Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstrasse 7, D-91058 Erlangen, Germany.
J Phys Condens Matter. 2009 Apr 1;21(13):134007. doi: 10.1088/0953-8984/21/13/134007. Epub 2009 Mar 12.
The stability of various point defects in NiAl(100) has been investigated by first-principles calculations. For Al-rich surfaces, Ni vacancies within the first Al layer are energetically most favourable. For Ni-rich surfaces, so-called double defects, consisting of both Ni-antisite atom in the first Al layer and a Ni vacancy within the second Ni layer, form the configuration of lowest energy, superior to singular Ni antisites. An additional and significant energy gain is found in both cases by mutual lateral interaction of the defects, when they are arranged in the diagonal direction. Respective [Formula: see text] ordered configurations were found as the most stable structures. A 50:50 mixture of both defect types turns out to be even lower in energy than the ideal Al-terminated NiAl(100) surface, proving the latter to be metastable only. This is in line with the often reported inability in experiments to prepare ideal NiAl(100) surfaces.
通过第一性原理计算研究了NiAl(100)中各种点缺陷的稳定性。对于富铝表面，第一层铝层中的镍空位在能量上最有利。对于富镍表面，由第一层铝层中的镍反位原子和第二层镍层中的镍空位组成的所谓双缺陷形成能量最低的构型，优于单个镍反位。当缺陷沿对角线方向排列时，在两种情况下都发现了缺陷间相互横向作用带来的额外且显著的能量增益。各自的[公式：见原文]有序构型被发现是最稳定的结构。两种缺陷类型的50:50混合物的能量甚至比理想的铝端接NiAl(100)表面更低，证明后者仅是亚稳的。这与实验中经常报道的无法制备理想NiAl(100)表面的情况一致。
