Temperature Dependence of Lattice Parameters in Martensite and Effect of the External Magnetic Field on Martensite Structure in Ni{sub}2MnGa Studied In Situ with Neutron Diffraction

摘要

The crystal structure of Ni{sub}1.99Mn{sub}1.14Ga{sub}0.87 single-crystal that exhibits large magnetic field induced strain in the martensitic phase is studied by neutron diffraction within temperature range 300K-4K. The 5-layered modulated structure is observed within the whole temperature interval and no another martensitic transformations occur. The anisotropic change of the martensite lattice parameters during cooling from 300K down to 4K is found. The combined change in the a- and c-lattice parameters affects change of the (c/a) ratio in martensite with cooling down by 2.32%. Redistribution of twin martensitic variants in the external magnetic field is studied in-situ at temperatures 98K-296K.