NANOPOWDERS OF R_2Fe_(14)B-TYPE COMPOUNDS IN HIGH MAGNETIC FIELDS: THE EFFECTS OF SUBSTITUTIONAL AND INTERSTITIAL ATOMS ON INTER-SUBLATTICE EXCHANGE INTERACTION

摘要

The fundamental magnetic characteristics of R_2Fe_(14)B intermetallics are highly sensitive to atomic substitutions and interstitial absorption of light elements. In this work, both were combined, and the influence of the substitutions in the R-sublattice and hydrogen absorption on the magnetization of (RR')_2Fe_(14)BH_x (R is Tm or Er, and R' is Nd) in magnetic fields up to 58Twas studied. (Tm_(0.5)Nd_(0.5))_2Fe_(14)B and (Er_(0.5)Nd_(0.5))_2Fe_(14)B were prepared. By using direct hydrogen absorption, (R_(0.5)Nd_(0.5))_2Fe_(14)BH_x compounds were obtained with hydrogen content 0≤x≤5.5. Magnetic measurements of both the parent alloys and their hydrides were carried out on nanopowders. The strength of the inter-sublattice coupling in (Tm_(0.5)Nd_(0.5))_2 Fe_(14)B, (Er_(0.5)Nd_(0.5))_2Fe_(14)B and their hydrides is estimated by analysing high-field magnetization data. Itis shown that hydrogenation weakens the inter-sublattice exchange interaction up to 45 %. (Tm_(0.5)Nd_(0.5))_2Fe_(14)B, with the maximum hydrogen content of 5.5 at.H/f.u., reaches the field-induced ferromagnetic state at about 55 T.