Magnetic properties of SmFe3 and its hydrogenation and nitrogenation

The magnetic properties of hydrogenated or/and nitrogenated SmFe ₃ alloys are studied. It is found that SmFe₃ can be readily hydrogenated while not nitrogenated. There are two hydrogenation temperatures, that at 195°C corresponding to the formation of SmFe₃H_x and that at 450°C corresponding to decrepitation of SmFe₃ phase forming SmH and α-Fe, respectively. The SmFe₃H_1.34 has the highest saturation magnetization of all, while anisotropy field decreases due to hydrogenation. The difficulty in nitrogenation is attributed to kinetic reasons of the formation of SmN compound, around 20 nm in size, on the surface or grain boundary of the powder, retarding further diffusion of nitrogen into the matrix