Determination of the magnetic and nuclear structure of Ni_{2.17}Mn_{0.83}Ga

Issue title: INABIO 2004

Article type: Research Article

Authors: Fröhlich, K.^a | Dennis, B.^a | Kanomata, T.^b | Matsumoto, M.^c | Neumann, K.-U.^{a; *} | Ziebeck, K.R.A.^a

Affiliations: [a] Physics Department, Loughborough University, Loughborough, LE11 3TU, UK | [b] Faculty of Engineering, Tohoku Gakuin University, Tagajo, 985-8537, Japan | [c] Institute of Advanced Materials Processing, Tohoku University, Sendai, 980-8577, Japan

Correspondence: [*] Corresponding author. E-mail: k.u.neumann@lboro.ac.uk

Abstract: The structure of Ni_{2.17}Mn_{0.83}Ga has been investigated as a function of temperature using neutron powder diffraction. Above T = 310 K the compound has the cubic L2_{1} structure, with lattice parameter a = 5.79 Å, and with the excess nickel atoms occupying the vacant manganese sites. Magnetisation and resistivity measurements indicate a Curie temperature of T = 340 K with a further transition at T = 301 K associated with a structural phase transition. The martensitic phase was found to have a tetragonal structure with cell parameters a = b = 3.87 Å and c = 6.47 Å and space group I4/mmm. Although there is negligible change in atomic volume the lattice parameters a and b change by ∼ 5.5% and the c-axis by almost 12%. The large change in cell parameters and the relatively high transition temperature make the compound a promising candidate for applications.

DOI: 10.3233/JAE-2005-680

Journal: International Journal of Applied Electromagnetics and Mechanics, vol. 21, no. 3-4, pp. 159-162, 2005