Mossbauer study of a binary amorphous ferromagnet: Fe80P20

Abstract

Binary amorphous Fe₈₀P₂₀ has been studied by ⁵⁷Fe Mossbauer spectroscopy. The results from this study are compared with those of Fe₈₀B₂₀ so that the influence due to the metalloid elements can be elucidated. The Curie temperature of T_C=580 K for Fe₈₀P₂₀ is considerably lower than that of 685 K for Fe₈₀B₂₀. The hyperfine field distribution {P(H) } of Fe₈₀P₂₀ is distinctively asymmetrical as opposed to a nearly symmetrical P(H) in Fe₈₀B₂₀. From the temperature dependence of the hyperfine field and the values of T_C we have concluded that both the mean exchange interaction (J₀) and the width (ΔJ) of the distribution of exchange interactions {P(J) } are considerably smaller in Fe₈₀P₂₀. A large difference in the isomer shift has also been observed in the two alloys. It is suggested that these large changes are in part caused by the electronic differences of phosphorus and boron. At high temperatures Fe₈₀P₂₀ crystallizes into Fe₃P and α‐Fe.