Hydrogen-alkali-metal-graphite ternary intercalation compounds
Hydrogen-alkali-metal-graphite ternary intercalation compounds
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氢-碱金属-石墨三元插层化合物
DOI：
10.1557/jmr.1990.0435
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
H. Inokuchi
中科院分区：
文献类型：
--
作者：
T. Enoki;S. Miyajima;M. Sano;H. Inokuchi
碱-金属-石墨插层化合物以物理吸附和化学吸附两种方式吸附氢。在高阶碱金属- gic中，通过物理吸附过程的氢吸收发生在约200 K以下的低温下，其中氢分子在石墨片的长廊中稳定形成二维凝聚相。吸收氢分子的浓度以H_2/碱金属原子~ 2的速率达到饱和。氢的物理吸附表现出较强的同位素效应和c轴晶格膨胀效应。在通过化学吸附过程吸收氢的情况下，离解的氢在插层空间中稳定下来。化学吸附活性按Cs < Rb < k的顺序增加。由于氢具有很强的电子亲和性，氢的引入产生了从宿主碱金属GIC向氢的电荷转移。氢化钾- gic具有由K^+-H^−-K^+三原子层三明治组成的插层，插入金属石墨片之间。插入的二维氢层由具有弱金属性质的氢离子组成。本文还从氢化钾- gic的电子和晶格动力学性质的变化方面讨论了氢化钾- gic的超导性。与过渡金属氢化物相比，碱金属- gic的吸氢现象从储氢的角度来看是一个有趣的现象。氢吸收法制得的氢-碱-金属三元GIC具有新颖的电子性质和晶格结构，为GIC的研究提供了有吸引力的问题。本文综述了氢-碱-金属三元GIC的研究进展。
Alkali-metal-graphite intercalation compounds (alkali-metal-GIC’s) absorb hydrogen in two ways: physisorption and chemisorption. Hydrogen uptake through the physisorption process occurs at low temperatures below about 200 K in higher stage alkali-metal-GIC’s, where hydrogen molecules are stabilized to form a two-dimensional condensed phase in the galleries of the graphite sheets. The concentration of absorbed hydrogen molecules is saturated at a rate of H_2/alkali metal atom ∼2. The hydrogen physisorption shows a strong isotope effect and a swelling effect on c-axis lattice expansion. In the case of hydrogen uptake through the chemisorption process, dissociated hydrogen species are stabilized in the intercalate spaces. The activity of the chemisorption increases in the order Cs < Rb < K. The introduction of hydrogen generates a charge transfer from the host alkali metal GIC’s to the hydrogen since hydrogen has strong electron affinity. The hydrogenated potassium-GIC’s have intercalates consisting of K^+-H^−-K^+ triple atomic layer sandwiches which are inserted between metallic graphite sheets. The inserted two-dimensional hydrogen layer is suggested to consist of H ions with a weakly metallic nature. The superconductivity of the hydrogenated potassium-GIC is also discussed in terms of the change in the electronic and lattice dynamical properties by hydrogen uptake. The hydrogen-absorption in alkali-metal-GIC’s is an interesting phenomenon in comparison with that in transition metal hydrides from the point of hydrogen storage. The hydrogen-alkali-metal-ternary GIC’s obtained from hydrogen absorption have novel electronic properties and lattice structures which provide attractive problems for GIC research. The studies of hydrogen-alkali-metal ternary GIC’s are reviewed in this article.