掺杂对Ni51.5Mn25Ga23.5相变行为和磁性的影响

通过往母合金Ni_51.5Mn₂₅Ga_23.5掺入7种IVA, VA和VIA 过渡族元素得到系列掺杂合金Ni_51.5Mn₂₃M₂Ga_{23 .5}.M为掺杂元素.实验结果表明，掺杂效应一般引起马氏体相变温度的下降，其中，W 的掺杂是7种元素中唯一使相变温度升高的特例，且出现了中间马氏体相变.同时，在价电子 浓度不变的情况下，相变更敏感于原子的尺度效应.实验发现，Ti，Zr，Hf，V四种非磁性元 素的掺杂使Mn原子磁矩减小，而Nb，Ta，W三种非磁性元素的掺杂却可以明显地增大Mn原子 的磁矩.在考察掺杂效应时，不能忽略马氏体相变引起的晶格变化对材料磁性的影响.关键词：NiMnGa掺杂马氏体相变磁性

Dopant effects on martensitic transition and magnetic properties of Ni51.5Mn25Ga23.5 materials

Ni_51.5Mn₂₃M₂Ga_23.5 materials are to reveal the dopant effect on the martensitic transition and the magnetic propert ies. We found that the dopants Ti, Zr, Hf, V, Nb, and Ta lower the martensitic transition temperature of the sample, but W increases it. The martensitic trans ition temperature is very sensitive to the atomic size when the valence electron ic concentration keeps constant for the doping elements. The dopants Ti, Zr, Hf or V decrease the magnetic moment of Mn atom in the martensite at low temperatur e, while Nb, Ta or W enhance it. A corresponding variation of T_C of t he materials is not observed, which indicates that the influence of the lattice change of martensitic transition on the magnetic properties should also be ta lken into account.