鉄欠損 R₂T₁₇ 型合金 Dy₂Fe_17-x-yAl_x の磁性

抄録

The ternary R₂T₁₇-type alloys Dy₂Fe_17-x-yAl_x with Fe deficiency have been studied by means of X-ray diffraction and magnetization measurements. The single phase boundary of R₂T₁₇-type structure was determined to be near the composition Dy₂Fe₉Al_x for x≥4 and Dy₂Fe_13-xAl_x for x≤4. The crystal structures are of the Th₂Ni₁₇-type for alloys with x≤5 while a Th₂Zn₁₇-type for those with 6≤x≤8. The thermo-magnetic curves show that the magnetism varies from P-type to N-type ferri-magnetism with an increase in the Al content x. Three types of spin arrangements, in which x≤2, 2<x≤5, 6≤x≤8, were proposed on the basis of the magnetic studies. It was concluded that the substitution of Al for Fe causes a derease in the Fe magnetic moment, but that defects in the Fe cause an increase in the Fe magnetic moment.