Magnetic properties and structure of (Fe100-xGex)0.95Ni0.05 alloys (x = 0, 5, 10, 15, 20)

Abstract In this paper structural and magnetic properties of Fe-based alloys (Fe100-xGex)0.95Ni0.05 (x = 0, 5, 10, 15, 20) were studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), magnetic and 57Fe Mossbauer spectroscopy measurements. Also, Density Functional Theory (DFT) calculations were used to study preferred crystal structure for Fe–Ni alloys with different Ge concentration. The results indicate that the addition of less than 20% Ge leads to preferred formation of alloys with bcc-type structure. The XRD measurement shows that all the investigated compounds have a body-centred cubic structure and the lattice constant increases with an increase in Ge concentration in the alloy from 2.87092 A ˙ (x = 0) to 2.88594 A ˙ (x = 20). The investigation of magnetic properties of (Fe100-xGex)0.95Ni0.05 proved their ferromagnetic behaviour, but magnetic moment per atom decreases with an increase in Ge concentration in the alloy from 2.31 μB (x = 0) to 1.66 μB (x = 20). In a temperature of about 820 K structural transformation from body-centred to face-centred cubic structure was observed for all the alloys. The temperature of this transformation was constant and independent of Fe or Ge concentration in the alloy.