氧原子在体心立方难熔金属中的占位行为的第一性原理研究

First-principles Study on the Site Occupation of Oxygen Atom in the BCC Refractory Metals

通过第一性原理超晶胞方法研究了氧(O)原子在体心立方(BCC)难熔金属Nb,Ta,Mo,W中不同间隙位置的占位稳定性和原子结构以及电子结构。杂质形成能结果表明,O原子占据在Nb,Ta的八面体间隙最稳定;与之相反,O原子占据在Mo,W的四面体间隙位置最稳定。进一步的,O原子在BCC难熔金属的杂质形成能由低到高的顺序为Nb<Ta<Mo<W,这表明金属中溶解氧容易顺序为Nb>Ta>Mo>W。此外,分析了O对难熔金属Nb,Ta,Mo,W原子结构的影响。利用电子结构态密度解释了氧原子在Nb,Ta八面体间隙和Mo,W四面体间隙的最稳定性原因。

With first-principles calculations and supercell model, the different site occupation stability, geometric and electronic structures of oxygen （O） atom were systematically investigated in the body- centered-cubic （BCC） Nh, Ta, Mo and W refractory metals （RMs）. Impurity formation energy result shows that, the O atom prefers to occupy at octahedral （Oct） site in the BCC Nb and Ta RMs, while the O atom likes occupying at tetragonal （Tet） site for oxygen in the BCC Mo and W RMs. Furthermore, the order of impurity formation energy of oxygen atom in the RMs is Nb 〈 Ta 〈 Mo 〈 W, which indicates that the stability and easy order of dissolved oxygen atom in the RMs is Nb 〉 Ta 〉 Mo 〉 W. In addition, the effect of O atom on the geometric structure of RMs was discussed and their electronic structures explained that the most stable site of O is the octahedral site in Nb and Ta as well as the tetrahedral site in Mo and