Helium stability and its interaction with H in alpha-Al2O3: a first-principles study
Helium stability and its interaction with H in alpha-Al2O3: a first-principles study
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氦稳定性及其与 α-Al2O3 中 H 的相互作用：第一性原理研究
DOI：
10.1039/c5cp06496a
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发表时间：
2016
影响因子：
3.3
通讯作者：
Wang Xiaolin
中科院分区：
文献类型：
--
作者：
Zhang Guikai;Xiang Xin;Yang Feilong;Peng Xuexing;Tang Tao;Shi Yan;Wang Xiaolin
由于氚衰变和(n，a)反应，α-Al2O3TPBS中存在着一种外部缺陷，即氢与氦的相互作用，人们对此知之甚少。用密度泛函理论研究了富氢条件下α-Al_2O_3中不同位置(VAl_3-Al_2O_3、V_0O、O_2-O_2和八面体间隙位)上与He有关的络合物的稳定性、结构、扩散以及与H的相互作用。He原子有利于Al空位的占据，OISs中心或在Al空位周围形成哑铃状，形成HeI、HeAl_3−、HeI-HeAl_3−、[VO-HeI]0和[O_2−-He]_2−络合物，其中HeAl_3−最容易形成。VAl_3−能吸引He形成小而稳定的He-HeAl_3−团簇，而只有一个He原子被OIS、VO和O_2−捕获。HeI更有可能扩散到VAl3、−和V0，而不是沿着c轴从一个OIS扩散到另一个OIS。Hi+捕获到HeAl3−和[VO-HeI]0在热力学和动力学上都是可行的，而[HeI-H+]+的解离更可行。α-Al_2O_3中H-He复合缺陷的形式有HeI、Hi+、[Hei-H+]+、[HeAl3−-H+]2−和[Ho+-Hei]+。HeAl_3、−和[VO-HeI]_0的存在增加了α-Al_2O_3中氢迁移的活化能，有利于热塑性硫化铝膜的低氢迁移。
Little is known about hydrogen interaction with helium, an extrinsic defect, present in α-Al2O3 TPBs due to tritium decay and (n, a) reaction. Using density functional theory (DFT), the stability, structure and diffusion of He-related complexes at the different positions (VAl3−, V0O, Oi2− and octahedral interstitial sites (OISs)) in α-Al2O3, as well as the interactions with H, are determined under H2-rich conditions. A He atom favors occupation of Al vacancies, the centers of OISs or forms a dumbbell around Al vacancies, forming Hei, HeAl3−, Hei–HeAl3−, [V0O–Hei]0 and [Oi2−–He]2− complexes, among of which HeAl3− forms most readily. VAl3− can attract He to form small stable He–HeAl3− clusters, whereas only a He atom is trapped by an OIS, V0O and Oi2−. Hei is more likely to diffuse into VAl3− and V0O than diffuse along the c-axis from one OIS to another. Hi+ trapping into HeAl3− and [V0O–Hei]0 is thermodynamically and kinetically feasible, whereas dissociation of [Hei–H+]+ is more feasible. Forms of H–He complex defects in α-Al2O3 are Hei, Hi+, [Hei–H+]+, [HeAl3−–H+]2− and [HO+–Hei]+. HeAl3− and [V0O–Hei]0 present will increase the activation energy of H migration in α-Al2O3, which is favored for low H transport of TPBs.