Martensitic transformation, magnetocaloric effect and phase transition strain in Ni50Mn36-xGexSn14Heusler alloys

In present work, the effect of Ge substitution for Mn on crystal structure and martensitic transformation was carefully investigated in magnetic shape memory Ni50Mn36-xGexSn14 (x = 0, 1) alloys. From X-ray diffraction (XRD) patterns, it can be found that each sample possesses cubic austenitic structure (L2(1)) at room temperature and the main peak (220) shifts to higher degree with Ge doping, indicating that the cell volume of austenitic phase shrinks. With Ge content increasing, martensitic transformation (MT), temperature shifts to higher temperature region and the difference of magnetization between martensitic and austenitic phases (Delta M) also increases. In addition, the magnetocaloric effect (MCE) and phase transition strain (Delta L/L) were investigated in Ni50Mn35GeSn14 alloy. The maximal magnetic entropy change (Delta S-m) associated with martensitic transition is 3.9 J center dot kg(-1)center dot K-1 with applied magnetic field change of 5 T and the maximal Delta L/L reaches 0.18% in this alloy.

Automated summary

This study investigated the effect of Ge substitution for Mn on crystal structure and martensitic transformation in Ni50Mn36-xGexSn14 alloys, showing that Ge doping leads to a shrinking of the cell volume of the austenitic phase and an increase in martensitic transformation temperature and magnetization difference. Additionally, a maximal magnetic entropy change and phase transition strain were observed in Ni50Mn35GeSn14 alloy.