Crystallographic and magnetic properties of ( R = Y, Ce, Nd, Sm, Gd, Tb, and Dy)

Abstract

A systematic investigation of crystallographic and magnetic properties of nitride (R = Y, Ce, Nd, Sm, Gd, Tb, and Dy) has been performed. Nitrogenation leads to a relative volume expansion of about 6%. The lattice constants and unit cell volume decrease with increasing rare-earth atomic number from Nd to Dy, reflecting the lanthanide contraction. On average, the Curie temperature increases due to the nitrogenation to about 200 K compared with its parent compound. Generally speaking, nitrogenation also results in a remarkable improvement of the saturation magnetization and anisotropy fields at 4.2 K and room temperature for compared with their parent compounds. The transition temperature indicates the spin reorientations of for R = Nd and Sm are at around 375 and 370 K which are higher than that of for R = Nd and Sm 145 and 140 K, respectively. The magnetohistory effects of (R = Ce, Nd, and Sm) are observed in low fields of 0.04 T. After nitrogenation the easy magnetization direction of is changed from an easy-cone structure to the b-axis. As a preliminary result, a maximum remanence of 0.94 T, an intrinsic coercivity of 0.75 T, and a maximum energy product of for the nitride magnet are achieved by ball-milling at 293 K.