Effect of Zn-doping on the phase transition and magnetic properties of Heusler alloys Ni_2MnGa_(1-x)Zn_x (x = 0, 0.25, 0.5, 0.75 and 1)

摘要

Transition metal Zn shows a main group element-like behavior in Heusler alloys Ni2MnGa1-xZnx (x = 0, 0.25, 0.50, 075 and 1.00). Zn enters Ga (D) site when it substitutes for Ga in Ni-2 MnGa chemically. The equilibrium lattice constant decreases with increasing Zn content. But at the same time the magnetic properties do not change too much. Mn partial moment contributes most to the total moment and couples parallel to that of Ni in both austenite and martensite. The partly substitution of Zn for Ga can lead to an increase of martensitic transition temperature due to the competition between cell volume effect and valence electron concentration e/a. Accordingly, the largest energy difference.EM between the austenite and martensite was found when x=0.5. This was further explained based on the electronic structure from the Jahn-Teller effect. Then Zn-doping can be used as a possible way to adjust the phase transition temperatures in Heusler type MSMAs. Zn is much cheaper than Ga or In, this can be quite meaningful for the development of high performance and low cost MSMAs and broaden their industrial applications.