A new ternary compound (Ni, Mn)2Ga in Ni-Mn-Ga system

A new ternary compound (Ni, Mn)2Ga was identified in Ni-Mn-Ga system by a combination of powder X-ray diffraction, differential thermal analysis and electron probe microanalysis. The (Ni, Mn)2Ga phase was determined with a Mn2Ge-type hexagonal structure, with lattice parameters of a = 4.1629(8) nm, c = 5.2983(9) nm, and unit cell volume of 0.07952(4) nm3 after refinement. The reversible phase transformation from (Ni, Mn)2Ga hexagonal structure to bcc (B2) cubic structure at high temperature was suggested by DTA measurements. The transformation peaking temperatures during heating and cooling are 834.0 °C and 815.8 °C for Mn40Ni25Ga35, 804.7 °C and 774.1 °C for Mn50Ni17Ga33, respectively.