Denitrogenation process in ThMn12 nitride by in situ neutron powder diffraction
ThMn(12) nitrides are good candidates for high performance permanent magnets. However, one of the remaining challenges is to transfer the good properties of the powder into a useful bulk magnet. Thus, understanding the denitrogenation process of this phase is of key importance. In this study, we investigate the magnetic and structural stability of the (Nd-0.(75), Pr-0.25)(1.)2Fe10.5Mo1.5Nx compound (x = 0 and 0.85) as function of temperature by means of neutron powder diffraction. Thermal dependence of the lattice parameters, formation of alpha-(Fe,Mo), as well as the nitrogen content in the nitrides are investigated by heating the compounds up to 1010 K. The decomposition takes place mainly via the formation of the alpha-(Fe,Mo) phase, which starts at around 900 K, whereas the nitrogen remains stable in the lattice. Additionally, we show that the magnetic properties of the nitrides [M(4 T) = 90 Am-2/kg H-c and = 0.55 T] are maintained after the thermal treatments up to 900 K. This study demonstrates that the ThMn12 nitrides with the Mo stabilizing element offer good prospects for a bulk magnet provided an adequate processing route is found.