Study on the Interaction Between Hydrogen Atoms and Metals Included in Hydrogen Storage Metals

储氢金属中氢原子与金属相互作用的研究

• 批准号: 11640580
• 负责人: MASUDA Yoshio
• 金额: $ 0.45万
• 依托单位: NIIGATA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11640580/
• 关键词: Hydrogen Storage Metals; Siebert-type Apparatus; DV-X α Method; Electronic Structure Analysis; Cluster Model; 圧力等温線(PCT線); DV-Xa法

The Siebert-type apparatus was made to measure pressure-concentration-isotherm (PCT) diagrams of metal hydrogen systems. The apparatus equipped with a horizontal sample container, was improved to minimize the dead space. A leak rate of the hydrogen of the apparatus was 4.82 x 10^<-4> Pa dm^3 s^<-1>. When PCT diagrams of LaNi_<4.5>Co_<0.5> - hydrogen systems were measured using this apparatus, the reproducibility of the diagram was invariably good. The enthalpy change (ΔH) and entropy change (ΔS) determined for LaNi_<4.5>Co_<0.5> -H_6 were -32.7 kJ mol(H_2)^<-1> and 113 J mol (H_2)^<-1> K^<-1>, respectively.The electronic structures of LaNi_5 , LaNi_5H_<0.2> (α phase ; P6/mmm) and LaNi_5H_6 (β phase ; P31m) were investigated by means of the DV-X α cluster method to understand the interaction between hydrogen and metals. It is found that the hydrogen atoms make a strong chemical bond with Ni (1) atoms rather than La atoms in both the phases of α and β. These results were not accord with the expectation from the heat of formations of the hydrides of La and Ni.In the case of LaNi_<4.5>Co_<0.5>, the bond order of Ni - Co changed somewhat stronger than that of Ni - Ni. This finding is consistent with the experimental results that LaNi_5 fails easily than LaNi_<4.5>Co_<0.5> by repetition of the procedure of the hydrogen absorption and desorption. The interaction between the metals and hydrogen atoms seems to be affected by the cluster size. The small cluster model (HNi_<13>La) was used in this study, it is necessary to study the electronic structures for larger cluster models than that used in this study.

利用sibert型仪器测量了金属氢体系的压力-浓度-等温线（PCT）图。该仪器配备了一个水平样品容器，改进，以尽量减少死区。该装置的氢气泄漏率为4.82 × 10^<-4> Pa dm^3 s^<-1>。当用该仪器测量LaNi_<4.5>Co_<0.5> -氢体系的PCT图时，图的重现性总是很好。LaNi_<4.5>Co_<0.5> -H_6的焓变（ΔH）和熵变（ΔS）分别为-32.7 kJ mol(H_2)^<-1>和113 kJ mol(H_2)^<-1> K^<-1>。采用v - x α簇法研究了LaNi_5、LaNi_5H_<0.2> （α相；P6/mmm）和LaNi_5H_6 （β相；P31m）的电子结构，以了解氢与金属的相互作用。结果表明，在α相和β相中，氢原子与Ni(1)原子形成较强的化学键，而与La原子形成较强的化学键。这些结果与La和Ni氢化物的生成热预测结果不一致。当LaNi_<4.5>Co_<0.5>时，Ni - Co的键序变化强于Ni - Ni。这与重复吸氢解吸过程中LaNi_5比lani_< 4.5>Co_<0.5>容易失效的实验结果一致。金属和氢原子之间的相互作用似乎受到团簇大小的影响。本研究采用的是小簇模型（HNi_<13>La），有必要对比本研究更大的簇模型的电子结构进行研究。

项目成果

三浦陽子: "ジーベルツ装置の試作とそれによるLaNi_<4.5>Co_<0.5>の水素吸蔵特性"希土類. No.34. 76-77 (1999)

Yoko Miura：“Sieverts 装置原型和 LaNi_<4.5>Co_<0.5> 的储氢性能”No.34（1999）。