57Fe hyperfine interaction parameters and selected magnetic properties of high purity MFe12O19 (M=Sr, Ba)

Abstract

Much of the confusion regarding the 57Fe Mossbauer spectroscopic hyperfine parameters of SrFe12O19 and BaFe12O19 at 300 K has been removed by means of an interlaboratory investigation of well-characterized samples prepared from high purity starting materials. In contrast to previous investigations, the contributions of each of the five Fe sublattices to the Mossbauer spectrum are discernible at 300 K and five components are necessary for an adequate fit of the data. The relative magnitudes of the hyperfine fields, Hn, and isomer shifts, [delta], are as follows: for SrFe12O19 and BaFe12O19: Hn(2b)Hn(12k)Hn(4f1) Hn(2a)Hn(4f2), for SrFe12O19 [delta](4f12), and for BaFe12O19 [delta]4f2), and for BaFe12O19 [delta](4f11)2)The high purity starting materials seem to have appreciable influences on both hyperfine interaction parameters and bulk magnetic properties as observed by others for spinel and garnet ferrites.