Magnetic Properties of Borides with a Cr₂₃C₆ Structure

Abstract

A series of Cr₂₃C₆-type borides was investigated by means of thermomagnetic measurements. The atomic magnetic moment (Curie temperature) of (Fe, Co)₂₀Al₃B₆ increases linearly from about 0.6 Bohr magnetons (403°K) for Co₂₀Al₃B₆ to a value of 1.5 Bohr magnetons (815°K) for Fe₈Co₁₂Al₃B₆. Partial replacement of the Ni in non-magnetic Ni₂₀Al₃B₆ by Fe also causes a smooth increase in moment (Curie temperature) and gives a value of 0.5 Bohr magnetons (285°K) for Fe₈Ni₁₂Al₃B₆. (Co, Ni)₂₀Al₃B₆ exists in a perfect solid solution and shows a peak in moment (Curie temperature) vs. composition curve at about Co₁₇Ni₃Al₃B₆.
These results can be accounted for in terms of an idea in which new magnetic moment is induced in these systems.