J. Phys. IV France 112 (2003) 963
Temperature dependence of martensite structure and its effect on magnetic-field-induced strain in Ni 2MnGa magnetic shape memory alloysN. Glavatska1, G. Mogilniy1, I. Glavatsky1, S. Danilkin2, D. Hohlwein2, A. Beskrovnij3, 4 and V.K. Lindroos4
1 Institute for Metal Physics, Vernadsky Blvd. 36, 03680 Kiev 142, Ukraine
2 Hahn-Meitner-Institut, Glienicker Str. 100, 14109 Berlin, Germany
3 Joint Institute for Nuclear Research, Joliot-Curie Str. 6, Dubna, Moscow Region 141980, Russia
4 Helsinki University of Technology, P. O. Box 6200, 02015 Hut, Finland
Structure in two Ni 2MnGa alloys, that exhibit large magnetic field induced strain in martensite phase, was studied with neutron diffraction in temperature range 4K-354K. It is found that lattice parameters in martensite notably change with temperature. The magnetic field induced strain value decreases/rises with the rise/decrease of temperature according to the change of (l-c/a) in martensite phase. The critical value of the magnetic field for activation of the twin's boundary motion decreases with increasing temperature.
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