High-pressure synthesis of MgNi intermetallic compound and its thermal stability

A novel intermetallic compound of MgNi was synthesized from amorphous MgNi by high pressure technique. Crystal structure, thermal stability and hydrogenation property of the compound were studied. The crystallized MgNi was synthesized at 573 K for 2 h under the pressure of more than 5 GPa, and was found to exhibit a CuTi-type structure with lattice parameters of a = 0.2997(1) nm, c = 0.3166(2) mn. The MgNi was decomposed into Mg2Ni and amorphous phase at 575 K and decomposed into Mg2Ni and MgNi2 over 682 K. Moreover the MgNi was hydrogenated into novel hydride with a CsCl-type structure at 355 K under 2 MPa hydrogen. This novel hydride with a lattice parameter of a = 0.3215(1) nm was decomposed into Mg2Ni and MgNi2 over 428 K under an Ar atmosphere.