Laboratoire de Physique et Chimie Quantique (LPCQ), Université Mouloud Mammeri, Tizi-ouzou, Algeria.
J Phys Condens Matter. 2010 Dec 8;22(48):485502. doi: 10.1088/0953-8984/22/48/485502. Epub 2010 Nov 16.
The energetic properties of the divacancy defect in fcc nickel are studied by ab initio calculations based on density functional theory. The formation and binding enthalpies of the divacancy in the first (1nn), second (2nn) and third (3nn) nearest-neighbor configurations are presented. Results show that the 1nn divacancy configuration is the most stable with a formation enthalpy H(2v)(f) of 2.71 eV and a small binding energy H(2v)(b) of 0.03 eV. In the 2nn configuration, the monovacancy-monovacancy interaction is repulsive, and it vanishes in the 3nn configuration. The migration process of the divacancy in its stable configuration is studied. We find that the divacancy migrates in the (111) plane by successive rotational steps of 60°. The corresponding migration enthalpy H(2v)(m) is predicted to be 0.59 eV, about half of that found for the monovacancy. For a better comparison of our results with high temperature experimental data, we have analyzed the effects of thermal expansion. Our results show that the inclusion of thermal expansion allows us to reproduce satisfactorily the experimental predictions.
基于密度泛函理论的第一性原理计算研究了面心立方镍中双空位缺陷的能量特性。给出了第一（1nn）、第二（2nn）和第三（3nn）最近邻配置中双空位的形成焓和结合焓。结果表明，1nn 双空位构型最稳定，形成焓 H(2v)(f)为 2.71eV，结合能 H(2v)(b)较小，为 0.03eV。在 2nn 构型中，单空位-单空位相互作用是排斥的，在 3nn 构型中则消失。研究了双空位在稳定构型中的迁移过程。我们发现，双空位通过连续的 60°旋转步骤在（111）平面上迁移。预测双空位的迁移焓 H(2v)(m)为 0.59eV，约为单空位迁移焓的一半。为了更好地将我们的结果与高温实验数据进行比较，我们分析了热膨胀的影响。结果表明，包含热膨胀可以使我们满意地重现实验预测。
