氧原子在Zr(0001)表面附近的扩散

Diffusion of oxygen atom near Zr(0001) surface

在密度泛函理论计算的基础上,利用微动弹性带(nudged elastic band)方法研究了氧原子在Zr(0001)表面附近的扩散.首先计算了氧原子从稳定的表面面心立方(SFCC)位置向表面六角密排位置的扩散激活能(0.77eV);然后计算了氧原子从稳定的SFCC位置扩散到表面下第1层与第2层之间的八面体间隙位置,再继续向表面下第2层与第3层之间的八面体间隙位置扩散的激活能,在此过程中氧原子需克服两个能垒,其激活能分别为2.14和2.57eV.结果表明,氧原子在Zr(0001)表面上方的扩散比较容易,而氧原子向Zr(0001)表面下的扩散相对较难.

Based on the density functional theory calculations, the diffusion of oxygen atoms near the Zr（0001 ）surface is studied by using the nudged elastic band method. Firstly, the active energy of diffusion of oxygen atoms from the surface face-centred cubic （SFCC） sites into surface hexagonal close-packed sites in Zr（0001） surface is calculated. The active energy for the diffusion is 0.77 eV. Secondly, the active energy of diffusion of oxygen atoms from the SFCC into octahedral interstitial sites between the second and third layers Octa（2,3） via octahedral interstitial sites between the first and second layers Octa（ 1,2） is calculated too. There are two energy barriers for oxygen atom to overcome. The active energies are 2.14 and 2.57 eV, respectively. As a result, the diffusion of oxygen atom above the Zr（0001） surface is easier than the diffusion into the subsurface.