Atomic-scale Ab-initio study of the Zr-H system: I. Bulk properties
Atomic-scale Ab-initio study of the Zr-H system: I. Bulk properties
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DOI：
10.1016/s1359-6454(02)00173-8
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发表时间：
2002-08-01
期刊：
影响因子：
9.4
通讯作者：
Legris, A
中科院分区：
文献类型：
--
作者：
Domain, C;Besson, R;Legris, A
在密度泛函理论的框架下研究了Zr-H体系的体积性质。局域密度近似（LDA）被发现是不够的一个适当的描述Zr和H原子之间的相互作用和广义梯度近似（GGA）是必需的。在alphaZr中，H原子在低温下优先占据四面体（T）位置，并且可以被认为在很短的距离内彼此独立，除了在同一间隙位置中的哑铃之间的排斥相互作用。Zr的电子态密度被H的存在所扰动，这导致了局域态的出现。H扩散沿着（c）在右箭头轴上优先发生在八面体（O）位置，并通过交替跳跃到T和O位置而发生在基面中。在γ（ZrH）、δ（ZrH_（1.5））和γ（ZrH_（2））中，H-H相互作用不可忽略，这些化合物的形成能几乎相等，表明它们的相对稳定性可能取决于机械和热对自由能的贡献，而在fee Zr中，H原子倾向于在接近ZrH的组成中采用平面排列。(C)2002 Acta Materialia Inc.由Elsevier Science Ltd.出版，版权所有。
Bulk proper-ties of the Zr-H system were studied in the framework of the density functional theory. The local density approximation (LDA) is found to be insufficient for a proper description of interactions between Zr and H atoms and the generalized gradient approximation (GGA) is required. In alphaZr, H atoms preferentially occupy tetrahedral (T) sites at low temperatures, and can be regarded as being independent of each other up to very short distances, except for repulsive interactions between dumbbells in the same interstitial site. The Zr density of electronic states is perturbed by the presence of H, which induces the emergence of localized states. H diffusion occurs along the (c) over right arrow axis preferentially in octahedral (O) sites, and in the basal plane by alternate jumps into T and O sites. In the gamma(ZrH), delta (ZrH1.5) and epsilon(ZrH2) hydrides, H-H interactions cannot be neglected, the nearly equal formation energies of these compounds indicate that their relative stabilities probably depend on mechanical and thermal contributions to free energies, and in fee Zr, H atoms tend to adopt planar arrangements for compositions close to ZrH. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.