High-pressure synthesis and energetics of MgCu with a CsCl-type structure

The novel intermetallic compound of MgCu with a CsCl-type structure has been prepared under high pressure, and its energetics including the enthalpy of formation has been discussed by means of density functional calculations. The MgCu phase with a lattice constant of a=0.3161 nm was prepared by using cubic anvil-type apparatus at 800 ° C under 6 GPa. For the first-principles calculation, a full potential linearized augmented plane wave (FPLAPW) technique was used. The lattice constant obtained as a result of volume optimization showed a good agreement with the observed value with an accuracy of less than 0.3%. From the calculation of the total energy, the enthalpy of formation of the novel MgCu phase was estimated to be - 18.4 kJ/mol. In addition, the MgCu phase decomposed into Mg₂Cu and MgCu₂ phases at around 520 K with ΔH=-2.2 kJ/mol (exothermic). The calculated ΔH (- 6.4 kJ/mol) also showed a fairly good agreement with the observed value.