Influence of High-Pressure Nitrogenation on the Structure, Magnetism and Microwave Absorption Properties of SmFe sub(10)Mo sub(2)

Nitrogenation of SmFe sub(10)Mo sub(2) powders was performed in a self-made furnace under a high-purity N sub(2) atmosphere up to 40 MPa at 500 [degrees]C. Upon nitrogenation at atmospheric pressure, the lattice parameters a and c increase by 0.5% and 2.7%, respectively, whereas the Curie temperature T sub(C) increases from 519 to 633 K. With further increasing the nitrogenation pressure to 20 and 40 MPa, the 1:12 main phase starts to decompose and a large amount of Mo and alpha -Fe precipitates. This leads to variation of Mo concentration in the 1:12 phase and causes a sharp decrease in T sub(C) and in the coercivity. The relative complex permittivity and permeability of paraffin-SmFe sub(10)Mo sub(2) composites show multi-resonant behavior. After nitrogenation, the magnetic loss of the powders decreases, which may originate from the influence of eddy currents due to the increase in the particle size.