A structural, magnetic, and Mössbauer study of the Dy2Fe17−xNbx solid solutions

Abstract The single-phase intermetallic compounds of refractory metal Nb doped Dy 2 Fe 17− x Nb x were prepared by arc melting. The substitution of Nb in the Dy 2 Fe 17 compound was found to have an important effect on their structure and magnetic properties. The Rietveld analysis of X-ray diffraction data shows that Dy 2 Fe 17− x Nb x ( x =0–1.5) solid solutions crystallize with the Th 2 Ni 17 structure. The lattice parameters obtained from Rietveld refinement show that the unit cell volume of Dy 2 Fe 17− x Nb x increases linearly with increasing Nb concentration up to x =1. The solubility of Nb was found to be limited to x ~1. The substitutional Nb atoms occupied all four sites in the order 12 j >12 k >6 g >4 f of a Th 2 Ni 17 structure. The Curie temperature ( T c ) was found to be Nb content dependent. The T c first increased and then decreased with increasing Nb content x , attaining a maximum value of 460 K at around x =1, which is 78 K higher than that of Dy 2 Fe 17 . The saturation magnetization decreased linearly with increasing Nb content from 69 emu/g for x =0 to 38 emu/g for x =1.5. 57 Fe Mossbauer spectra show the presence of DyFe 3 and NbFe 2 phases at a higher Nb content x ≥1. The hyperfine field values of 4 f site first increased up to x =1 and then decreased at higher Nb content.