Mössbauer spectroscopy in the system (Nd_1-xCe_x)_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 (Nd_1-xCe_x)_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, 〈B_hf〉, improve for all alloys after nitrogenation process. The Nd_1.1Fe₁₀CoTi (x = 0) and (Nd_0.5Ce_0.5)_1.1Fe₁₀CoTi (x = 0.5) alloys that present weigh fractions of 75 and 73%, respectively, with the ThMn₁₂₋type tetragonal structure present a 〈B_hf〉 of 30.9 and 31.0 T, respectively, after nitrogenation. Then, they can be possible candidates for rare earth-lean permanent magnets.