MnAl₆およびMnAl₄相の結晶構造

抄録

Crystal structures of intermetallic MnAl₆ and MnAl₄ phases, were determined by the powder X-ray diffraction method on the specimens extracted electrolytically from the binary alloy. The transformation reaction from MnAl₄ to MnAl₆ was also discussed. Results obtained were as follows.
(1) The MnAl₆ phase is a C-face centered orthorhombic structure, lattice parameters were measured as a = 7.564Å, b = 6.500Å, c = 8.883Å, the space group is D¹⁷_2h-Cmcm, and the density is 3.25g/cm³. The crystal composition is MnAl₆ and a unit cell contained 4 formula units.
(2) The MnAl₄ phase is a simple orthorhombic structure, lattice parameters are a = 6.795Å, b = 9.343Å, c = 13.897Å, the space group is D²_2h-Pnnn, and the density is 3.65g/cm³. The crystal composition is MnAl₄ and a unit cell contained 12 formula units.