Magnetic and structural phase transitions in Heusler type alloys Ni2MnGa1 xInx

X-ray diffraction, magnetization, electrical resistivity and thermal expansion measurements were done on a series of Heusler alloys of the form Ni2MnGa1-xInx 0 < x < 0.25. X-ray diffraction patterns indicate that the samples possess a highly ordered Heusler alloy L21 type structure. Due to the larger radii of the In ion, the lattice parameters were found to expand with increasing In concentration. The negative volume anomaly (∼ - 0.1%) is found to accompany the martensitic transition. With increasing In content, a linear decrease of the martensitic transition and the Curie temperatures were observed. The compositional- transition temperature phase diagram is evaluated. Possible reasons for the structural transformations are discussed.