Hydrogenation and Dehydrogenation Behavior of LaNi<SUB>5-x</SUB>Co<SUB>x</SUB> (x=0, 0.25, 2) Alloys Studied by Pressure Differential Scanning Calorimetry

• Asano Kohta

  Department of Materials Science, Graduate School of Engineering, Tohoku University

• Yamazaki Yoshihiro

  Department of Materials Science, Graduate School of Engineering, Tohoku University

• Iijima Yoshiaki

  Department of Materials Science, Graduate School of Engineering, Tohoku University

Bibliographic Information

Other Title

• Hydrogenation and Dehydrogenation Behavior of LaNi5-xCox(x=0, 0.25, 2) Alloys Studied by Pressure Differential Scanning Calorimetry

Abstract

The hydrogenation and dehydrogenation behavior of LaNi₅, LaNi_4.75Co_0.25 and LaNi₃Co₂ was studied by the pressure differential scanning calorimetry (PDSC) at the hydrogen pressure range of 1 to 5 MPa in the temperature range from 323 to 473 K with the heating and cooling rates of 2 to 30 K min⁻¹. In the heating run of the hydride of LaNi₅, two endothermic peaks were observed. One was the peak for the transformation from the γ phase (full hydride LaNi₅H₆) to the β phase (hydride LaNi₅H₃). The other was the peak for the transformation from the β phase to the α phase (solid solution). In the cooling run, one exothermic peak for the transformation from the α phase to the γ phase was observed. These endothermic and exothermic peaks shifted to higher temperatures with the increase in hydrogen pressure. In the heating and cooling runs of the LaNi_4.75Co_0.25–H₂ system the PDSC curves similar to those of the LaNi₅–H₂ system were observed. However, in the heating run of the hydride of LaNi₃Co₂ only one endothermic peak was observed. Using Ozawa’s method, the activation energies for dehydrogenation of the hydrides were estimated. The activation energy for the γ-β transformation was higher than that for the β-α transformation. Substitution of cobalt for a part of nickel in LaNi₅ increased the activation energies for the phase transformations.

Journal

• MATERIALS TRANSACTIONS

  MATERIALS TRANSACTIONS 43 (5), 1095-1099, 2002

  The Japan Institute of Metals and Materials

Keywords

• metal-hydride
• lanthanum-nickel-cobalt alloy
• hydrogen storage alloy
• pressure differential scanning calorimetry
• Ozawa’s method
• activation energy for transformation

Details

• CRID: 1390001204247821056
• NII Article ID: 10012323523
• NII Book ID: AA1151294X
• DOI: 10.2320/matertrans.43.1095
• COI: 1:CAS:528:DC%2BD38Xlt1entbc%3D
• ISSN: 13475320
• ISSN: 13459678
• NDL BIB ID: 6180251
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I6180251
• Web Site: https://www.jstage.jst.go.jp/article/matertrans/43/5/43_5_1095/_pdf
• Text Lang: en
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
• Abstract License Flag: Disallowed