An experimental study is presented of the multiple phase transitions occurring in the single crystals of Ni2MnGa, which had first been stressed and unloaded at liquid nitrogen temperature. The measurements of the specific heat, of the low-field magnetic susceptibility and of the ultrasonic velocity reveal that the material experiences the first-order structural phase transitions at T3 = 190 K, at T2 = 230 K, and at T1 = 290 K. The relative deformation not resulting in the plastic flow of the crystal was ΔL/L = 0.05. After unloading the dimensions and the shape of the samples were restored upon heating. The new phases appear in Ni2MnGa because of an anomalous instability of the lattice of this compound with respect to atomic displacements along a 〈110〉 direction in the (110) plane.
|Number of pages||7|
|Journal||International journal of applied electromagnetics in materials|
|Publication status||Published - 1994 Oct|
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