Formation of superabundant vacancies in Pd-H alloys
Formation of superabundant vacancies in Pd-H alloys
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DOI：
10.1016/s0925-8388(00)01195-6
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发表时间：
2000-12-15
影响因子：
6.2
通讯作者：
Watanabe, K
中科院分区：
文献类型：
--
作者：
Fukai, Y;Ishii, Y;Watanabe, K
使用同步加速器辐射通过X射线衍射测量了Pd晶格参数在高氢压力（2-5 GPa）和温度（672-896℃）下的时间变化，观察到的晶格收缩被解释为由于形成大量空位-氢（Vac-H）簇，即过剩空位。结果分析得出的结论是，大部分 Vac-II 团簇（相当于 10 at.%）是在某些内部来源形成了少量团簇后，通过表面扩散引入的。 Vac-H 团簇在高温下的热平衡浓度表现出饱和行为，这表明团簇存在最大可能浓度（约 16 at.%）。 Vac-H团簇的形成能、熵和体积分别为0.72 eV、7.2k和0.60 Ohm，迁移能和体积分别为1.20 eV和0.49 Ohm。还讨论了结果的各种其他含义。 (C) 2000 Elsevier Science B.V. 保留所有权利。
Temporal variation of the lattice parameter of Pd was measured under high hydrogen pressures (2-5 GPa) and temperatures (672-896 degreesC) by X-ray diffraction using a synchrotron radiation, and observed lattice contraction was interpreted as being due to the formation of a large number of vacancy-hydrogen (Vac-H) clusters, i.e. superabundant vacancies. Analysis of the: result led to the conclusion that a major part of Vac-II clusters (amounting to similar to 10 at.%) were introduced by diffusion from the surface, after a small number of them had been formed at some internal sources. The thermal-equilibrium concentration of Vac-H clusters at high temperatures shows a saturation behavior, which indicates the presence of a maximum possible concentration (ca.16 at.%) of the clusters. The formation energy, entropy and volume of a Vac-H cluster are found to be 0.72 eV, 7.2k and 0.60 Ohm, respectively, and the migration energy and volume are 1.20 eV and 0.49 Ohm respectively. Various other implications of the results are also discussed. (C) 2000 Elsevier Science B.V. All rights reserved.