Preparations and applications of Highly Concentrated Metal Hydrides

Research Project

Project/Area Number	61550008
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Applied materials
Research Institution	Yokohama National University
Principal Investigator	YAMAGUCHI Masuhiro Fac. of Engineering, Yokohama Natl. Univ., Associate Professor, 工学部, 助教授 (10018046)
Co-Investigator(Kenkyū-buntansha)	SUEZWAW Yasutaka Fac. of Engineering, Yokohama Natl. Univ., Associate Professor, 工学部, 助教授 (30143738)
Project Period (FY)	1986 – 1987
Project Status	Completed (Fiscal Year 1987)
Budget Amount *help	¥2,100,000 (Direct Cost: ¥2,100,000) Fiscal Year 1987: ¥500,000 (Direct Cost: ¥500,000) Fiscal Year 1986: ¥1,600,000 (Direct Cost: ¥1,600,000)
Keywords	metal hydride / hydrogen-absorbing alloy / magnetic materials / semiconductor / hydrogen / マグネシウムニッケル合金 / イットリウム・コバルト合金 / 水素吸蔵用合金 / 磁性 / 電気抵抗 / 稀土類元素
Research Abstract	We have formed highly concentrated metal hydrides form intermetallic compounds to modify their electrical and magnetic properties as follows: 1. The films of Mg_2NiH_x, FeTiH_x, LaNi_5H_x and LaCo_5h_x can be prepared. The films which are made on glas substrates by means of flash evaporation are reacted with hydrogen at a high pressure. The hydride films are very stable against several cycles of hydriding and dehydriding reactions. 2. The absorption spectrum of the Mg_2NiH_x film shows that the absorption edge is located near 1.6eV. This agrees with the calculated value for Structure I (1.36eV), rather than that for structure II (0.8eV). This measurement is the first finding about the band gap of a semiconductive metal hydride. 3. The Hall coefficients of LaNi_5H_x and LaCo_5H_x films have been measured as a function of hydrogen pressure and temperature. These substances show the anomalous Hall effect. It is likely that Ni or Co particles are segragated during hydrogen absorption. 4. The hydrogen absorbing alloys have been developed, which are based on YCo_3 and partially substituted substituted with Ni or Fe for Co. We can control the equilibrium hydrogen pressure by variying the Ni or Fe content. 5. The magnetic properties of the hydrides of Y(Co/Ni/Fe)_3 compounds depend strongly upon hydrogen composition.