Enhanced magnetization and cation distributions in nanocrystalline ZnFe/sub 2/O/sub 4/: a conversion electron Mossbauer spectroscopic investigation

The synthesis of nanocrystalline zinc ferrite (ZnFe/sub 2/O/sub 4/) has been accomplished by a variety of chemical and mechanochemical techniques. An enhanced magnetization, 4-5 times that of bulk zinc ferrite, is observed for the nanoparticles regardless of the synthesis method. The hypothesis that the enhanced magnetization is due to partially inverted nanocrystalline zinc ferrite has been examined by transmission /sup 57/Fe Mossbauer spectroscopy (TMS), conversion X-ray Mossbauer spectroscopy (CXMS) and conversion electron Mossbauer spectroscopy (CEMS). Both TMS and CXMS data indicate differences in local structure between bulk and nanocrystalline samples, however they do not suggest that the samples are partially inverted. CEMS data are similar for both bulk and nanocrystalline samples, indicating similar cation distributions near the surface of nanocrystalline and bulk particles.