Magnetic Properties of R2Fe17−xMx ( R = Y, Tm, Ho and M = Ni, Al) and Y2−xThxFe17 Compounds

The effects of varying electron concentration on the magnetic ordering of R2Fe17 compounds have been investigated in the temperature range 4.2K to above the Curie temperature (Tc). Tc increases sharply and reaches a maximum of 610K in the R2Fe17−xNix ternaries and 432K in the R2Fe17−xAlx ternaries. Y2−xThxFe17 ternaries do not show an increase in Tc. Saturation moments measured at 4.2K show a small increase for the thorium and nickel substituted ternaries, whereas Al substituted ternaries decrease in moment. Tm2Fe17 and the Ni and Al ternaries show an unusual thermal magnetization behavior with peaks interpreted as magnetic structure transformation and anisotropy effects. The results are discussed in terms of site preference and distance dependence of magnetic interactions.