MOSSBAUER STUDY OF A BINARY AMORPHOUS FERROMAGNET - FE80P20

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 TC=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 TC 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.