Effects of Sn vacancy and excess Sn doping on structural, magnetic and electrical properties of Ni47Mn40Sn13 ferromagnetic shape memory alloy

Abstract

In this work, the effects of Sn vacancy and excess Sn doping on the structural, magnetic and electrical properties of Ni47Mn40Sn13±x (x = 0, 0.5, 1) ferromagnetic shape memory alloys were investigated. X-ray diffraction pattern of the Ni47Mn40Sn13±x alloys indicated austenitic phase with L21 structure for x = 0. However, with increasing Sn vacancy, the coexistence of austenitic and martensitic phases was obtained, while all the compounds of the Ni47Mn40Sn13+x were in the austenitic phase at room temperature. By creating Sn vacancy and excess Sn doping, the martensitic transformation (MT) temperature decreased and Curie temperature of austenite (TcA) did not show a significant change. In addition, the electrical resistivity behaviors of all the samples revealed a good agreement with AC susceptibility measurements. The decrease of the MT temperature with the increase of Sn vacancy and excess Sn doping was also discussed on the basis of the valence electron concentration and cell volume variation.