Mossbauer spectroscopy has been used in Fe/(SiO2,BN) granular solids i
n order to elucidate the large differences in their coercivity values.
The Mossbauer data suggest a core/shell morphology for the Fe/SiO2 fi
lms with an Fe(Si) core surrounded by an Fe-Si-O shell whose surface c
onsists of Fe2+-Si-O particles. In Fe/BN the data indicate the presenc
e of amorphous FeB particles in a BN matrix.