EFFECT OF INTERSTITIAL HYDROGEN AND NITROGEN ON THE MAGNETOCRYSTALLINE ANISOTROPY AND MAGNETOSTRICTION OF RARE - EARTH ― TRANSITION - METAL INTERMETALLICS

摘要

The effects of the hydrogen and the nitrogen on the magnetic properties (the Curie temperatures, saturation magnetization and magnetic anisotropy) of RFe_(11)Ti and R_2Fe_(17) compounds are studied. Structural and magnetic investigations has been performed by means of X-ray diffraction, torque and pendulum magnetometer techniques and high-field magnetization measurements on single crystal RFe_(11)TiH_(1-δ) and the magnetically aligned powder samples RFe_(11)TiN_x, R_2Fe_(17)H_x and R_2Fe_(17)N_x. The hydrides and nitrides still retain the structure of their parent compounds, but the unit cell volumes are expanded. The Curie temperature are increased by both hydrogenation and nitrogenation. Magnetic phase diagram of RFe_(11)TiH_(1-δ) and RFe_(11)TiN_(1-δ) compounds have been obtained. The signs of the first constants of magnetic anisotropy of a rare earth sublattice are in agreement with the sign of the Stevens factor of rare earth ions. The effect of the hydrogen and nitrogen atoms on rare-earth sublattice anisotropy have been found to be opposite.