Magnetic and Structural Investigations on Substituted Pr(2)Co(17-x)T(x) Systems (T=Fe, Mn, Cr, Cu and Al)

摘要

Magnetic and structural characteristics of Pr2Co17-based ternaries, in which Co is partly replaced by other transition elements, namely Fe, Mn, Cr, Cu and Al, have been investigated. The objective of the work was to explore the possibility of enhancing the anisotropy of Pr2Co17 to the point that it would be useful for permanent magnet fabrication. X-ray diffraction indicates that all the systems studied occur in the rhombohedral Th2Zn17 structure. The cell constants increase as Fe, Mn, etc., are introduced in the system, which indicates that substitution occurs in the Co sublattice. The Curie temperatures, T subscript C, decrease monotonically with increasing x in the order Fe < Cu < Mn < Al < Cr. The saturation magnetization, M subscript s, increases with increasing x for the Fe system with x < or = 8. For x > 8 in the Pr2Co17-x Fex system and in all other ternary systems studied, M subscript s, decreases with x, the magnitude of the effect being in the order Cr > Al > Mn > Cu. The rate of decrease is larger than that expected as a simple dilution except for the systems containing Cu. Significant modification of the anisotropy characteristics of PrCo17 is observed upon substitution. The planar anisotropy of Pr2Co17 becomes uniaxial with Fe (x > or = 4) and Mn (x > or = 2) substitutions. With Cr and Al substitutions, the plane-seeking tendency of Pr2Co17 is significantly weakened.