Hydrogen absorption–desorption in CeNi2

Hydrogen absorption and desorption properties of CeNi2 compound are presented. Hydrogen absorption leads to the formation of CeH3 and CeNi2Hx, with a variation of the cell parameter of the compound from a = 7.201 Å to 7.093 Å. The hydrogen content in the compound is around 0.5 H/M under a hydrogen pressure of 0.03 MPa at 475 K. The enthalpy of CeNi2 hydride formation was measured to be −25 kJ molH−1 by thermal analysis. From thermal desorption analysis the activation energies for hydrogen desorption from the CeNi2 hydride was estimated to be about 50 kJ/mol. The location of hydrogen in tetrahedral sites has been identified from a semi-empirical description of hydrogen absorption in CeNi2 structure by Miedema model.