EFFECT OF MANGANESE SUBSTITUTION IN R₂AlFe_16-x Mn_x(R=Y,Ho,Nd AND Pr)COMPOUNDS ON STRUCTURAL AND MAGNETIC PROPERTIES

The structural and magnetic properties of R₂AlFe_16-xMn_x(0≤x≤8 for Y,Ho,0≤x≤10 for Pr, 0≤x≤16 for Nd) compounds have been investigated by means of X-ray diffraction and magnetization measurements.The R₂AlFe_16-xMn_x compounds have a hexagonal Th₂Ni₁₇-type structure for R=Y and Ho, and a rhombohedral Th₂Zn₁₇-type structure for Nd and Pr.With increasing x, the unit-cell volumes have a small increase initially,followed by a greater linear increase.The Curie temperature and the saturation magnetizati on of these compounds show marvelous drop with increasing x. Compensation point was observed in the temperature dependence of the magnetization for Ho₂AlFe₁₂Mn₄ compound.