Diffusion of hydrogen in metals
Diffusion of hydrogen in metals
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DOI：
10.1007/978-94-011-0295-7_12
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
H. Schober
中科院分区：
文献类型：
--
作者：
H. Schober
氢在金属中的扩散速度比其他原子快得多。两种不同的（示踪剂和化学）扩散系数被区分开来。依赖于主晶格和位置占用的扩散是通过接近经典的跳跃或通过隧道机制（量子扩散）。bcc金属中八面体间隙对氢的捕获为详细研究隧道机制提供了可能。此外，还观察到声子辅助隧穿的非绝热电子效应。为了理解扩散机制，许多不同的能量尺度是相关的。介绍了标准小极化子理论，并讨论了其在高能和低能的推广。对于较大的氢浓度，扩散系数变得强烈依赖于浓度。
Hydrogen diffuses in metals much faster than any other atom. Two different (tracer and chemical) diffusion coefficients are distinguished. Dependent on the host lattice and site occupation diffusion is by nearly classical jumps or by a tunneling mechanism (quantum diffusion). Trapping of hydrogen by octahedral interstitials in the bcc metal opens the possibility to study tunneling mechanism in details. Besides phonon assisted tunneling nonadiabatic electron effects are observed. For an understanding of the diffusion mechanisms a number of different energy scales are relevant. Standard small polaron theory is introduced and its extensions to higher and lower energies are discussed. For larger hydrogen concentrations the diffusion coefficient becomes strongly concentration dependent.