In this Paper the superparamagnetism of the oxidzed surface layer of fine iron paricles is reported. Fine iron particles in the range of size from 15 to 50nm with oxidized surface ayer were prepared by evaporation in nitrogen atmosphere. The sizes were measured by the BET method and transmission electron microscope (TEM). X-ray and electron diffraction analysis show that the particle is coposed of α-Fe core and a sufrface layer of Fe3O4. The thickness of the outer oxidized layer is about 2nm and is independent of the average diameter of the particles. The results indicate that the transition of the domain structure plays an important role in the superparamagnetic behavior of the oxide surface layer of iron particles. The emergence of the superparamag-netism at low temperature, may be a diagnostic of the transttion from the smgle domain to multi-domain structre for inner core. The criticle size of the single domain domain is esatimated at-about 40nm.

The use of Gev heavy ion beam irradiation has auracted much attention in the field of material science. In the case of garnets, the superexchange inreraction among the maguetie cations in the materials is very sensitive to the electronic stopping power of the beam. The induced microstructure and magnetic propertics of irradiated Ca V Sn: YIG samples have been characterized by means of Mossbauer spectroscopy, high resohution electron microscopy (HREM), X-ray diffraction (XRD), positron annihilation techniques (PAT), vibrating sample magnetometry and ferrimagnetic resonance (FMR). The experimental results are discussed in this paper.

A novel member of the Prussian blue family, cu3Ⅱ [FeⅢ (CN) 6] 2. 3NH3·6H2O, was synthesized, in which NH3 ligands are in stochastic distribution. We present x-ray diffraction data, zero-field-cooled magnetization and field-cooled magnetization curves, Mössbauer spectra with/without an xternal Field of 5 T and a structural model. This Prussian blue analogue displays considerable magnetic hardness below the magnetic transition temperature Tc, which is about 19.8K. The coercive field determined from the magnetization hysteresis loop at 5 K was 2.76 kOe. The copper-iron cyanometallates have potentlal applications in the design of novel magnetic systems.

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