Mössbauer spectroscopy in the system (Nd1-xCex)1.1Fe10CoTi with ThMn12 structure

In this work, we examined the effects of the of Nd by Ce substitution and of the nitrogenation in the structural and hyperfine magnetic properties of (Nd1-xCex)1.1Fe10CoTi with x = 0, 0.5 and 1 systems. The alloys were prepared, with high pure elements, by arc-melting and the pieces were then homogenized at 1100 °C for 48 h. The nitrogenation was carried out at 450 °C for 1 h with a pressure of 0.1 MPa. The X-ray diffraction analysis allowed to identify the ThMn12-type structure mainly with average weigh fraction of 68%. The obtained tetragonal ThMn12 structure type presented an increased lattice parameter after nitrogenation for all alloys. The rhombohedral structure Th2Zn17-type is also present in the alloys and their lattice parameters do not show important changes after the nitrogenation. The Mössbauer spectra were fitted with seven sextets and a small quadrupolar component, the sextets were associated to the Fe sites in the ThMn12-type and Th2Zn17-type phases. The mean field, 〈Bhf〉, improve for all alloys after nitrogenation process. The Nd1.1Fe10CoTi (x = 0) and (Nd0.5Ce0.5)1.1Fe10CoTi (x = 0.5) alloys that present weigh fractions of 75 and 73%, respectively, with the ThMn12−type tetragonal structure present a 〈Bhf〉 of 30.9 and 31.0 T, respectively, after nitrogenation. Then, they can be possible candidates for rare earth-lean permanent magnets.