LaS/CeS与γ-Fe异相界面性质的第一性原理计算

First-principles calculations of interface characteristics between LaS/CeS and γ?Fe

摘要:

为了探讨LaS/CeS与γ?Fe两相之间的异相界面性质，本文采用边?边匹配(E2EM)模型计算了LaS/CeS与γ?Fe两相之间晶体学上的原子匹配情况，基于晶体学计算结果，采用基于密度泛函理论的第一性原理，从原子尺度计算了LaS/CeS与γ?Fe之间的界面结合性质与界面能。晶体学计算表明，LaS/CeS与γ?Fe之间沿匹配列的原子间距错配度最小值为10.63 %/10.52 %，密排面间距错配度最小值为2.04 %/3.32 %；LaS与γ?Fe之间粗略的位向关系为：LaS∥γ-Fe & LaS∥γ-Fe和LaS∥γ-Fe & LaS∥γ-Fe ;CeS与γ?Fe之间粗略的位向关系为：CeS∥γ-Fe & CeS∥γ-Fe和CeS∥γ-Fe & CeS∥γ-Fe。基于预测的晶体学位向关系，采用相干界面近似构建了6种不同终端界面模型，第一性原理计算表明，LaS/CeS与γ?Fe之间原子匹配错配度最低界面的粘附功为4.78J·m?2/3.65J·m?2，界面结合强度较高，界面键合以金属键为主。异相界面能计算表明，LaS/CeS与γ?Fe两相之间的原子匹配错配度越小，界面能越低，原子匹配错配度最小时，界面能分别为?0.58J·m?2/?3.43J·m?2，计算结果能够为LaS/CeS与γ?Fe之间的晶体学匹配提供能量学依据。

Abstract:

In order to investigate the heterogeneous-interface characteristics between LaS/CeS and γ-Fe, the edge-to-edge matching (E2EM) model was employed to calculate the atomic matching mismatch between LaS/CeS and γ-Fe from the crystallographic point view. On the basis of the crystallographic calculations, the first-principle calculation based on the density functional theory was performed to calculate the interfacial bonding characteristics and the interface energy between LaS/CeS and γ-Fe on the atomic scale. The crystallographic calculations indicated that the minimum of the interatomic spacing misfit between LaS/CeS and γ-Fe along the matching direction was 10.63%/10.52%, and the minimum of interplanar spacing mismatch is 2.04%/3.32%, respectively. The rough orientation relationships (ORs) were predicted as follows: LaS∥γ-Fe &LaS∥γ-Fe and LaS∥γ-Fe &LaS∥γ-Fe; CeS∥γ-Fe &CeS∥γ-Fe and CeS∥γ-Fe &CeS∥γ-Fe. Based on the predicted ORs, six interface models with different atomic terminations were constructed using the coherent interface approximation. The first-principles calculations showed that the adhesion work of the interface between LaS/CeS and γ-Fe with the lowest interatomic mismatch was 4.78J·m-2/3.65J·m-2，which indicated the larger bonding strength of the interface between LaS/CeS and γ-Fe with the lower interatomic mismatch. The interface bond was dominated by the metal bond. The calculations of interface energy between LaS/CeS and γ-Fe indicated that the smaller the interatomic mismatch was, the lower the interface energy was obtained. The interface energy between LaS/CeS and γ-Fe with the lowest interatomic mismatch was -0.58J·m-2/-3.43J·m-2. The first-principles calculations can provide the theoretical foundations from the energetics point view for the crystallographic matching between LaS/CeS and γ-Fe. current method.