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Abstract: Size-controlled Mn0.67Zn0.33Fe2O4 nanoparticles in the wide range from 80 to 20nm have been synthesized, for the first time, using the oxidation method. It has been demonstrated that the particle size can be tailor-made by varying the concentration of the oxidant. The magnetization of the 80nm particles was 49Am2 kg−1 compared to 34Am2 kg−1 for the 20nm particles. The Curie temperatures for all the samples are found to be within 630±5K suggesting that there is no size-dependent cation distribution. The critical particle size for the superparamagnetic limit is found to be about 25nm. The effective magnetic anisotropy constant is experimentally determined to be 7.78kJm−3 for the 25nm particles, which is about an order of magnitude higher than that of the bulk ferrite. [Copyright &y& Elsevier]

Crystallographic structures and magnetic properties of chemically synthesized FePt nanoparticles, which were firmly stabilized into a monolayer on thermally oxidized Si substrate using 3-amino propyldimethylethoxysilene, were studied. The two-dimensional structure of FePt nanoparticles was confirmed by plan-view high-resolution scanning microscopy observation. The particles transformed from fcc to highly ordered L10 structure by annealing at 800°C under high vacuum with minimal coalescence. From rotational hysteresis loss analysis, a large magnetic anisotropy field of over 80 kOe for the 800°C-annealed film was estimated. The coercivity of the annealed sample was very small and of the order of 102 Oe at room temperature, meanwhile, the remanence coercivity obtained from DC demagnetization measurement was over 11 kOe. This large difference was resulted from the co-existence of Fe-poor particles with different low anisotropy fields in the monolayered film. [Copyright &y& Elsevier]

We here present the details of fullerene filling inside double-walled (DWNTs) and multi-walled carbon nanotubes (MWNTs) and also demonstrate plasma ion-irradiation effects on various kinds of nanotube structures. It is found that both the degree of the structural deformation and the fullerene filling efficiency are directly proportional to the applied bias voltage and plasma density used. In particular, in the case of relatively low substrate-bias application, irradiated fullerenes are only adsorbed on the surroundings of the DW/MWNTs, which are kept under end-cap structure. However, it should be noted that fullerene-like material filled DWNTs are shown to be formed by relatively high substrate-bias application, which frequently provokes nanotubes to form open-end structures. [Copyright &y& Elsevier]

The extended X-ray absorption fine structure (EXAFS) method and transmission electron microscopy (TEM) have been used for characterizing the local structure and morphology of ferric oxyhydroxides, α-FeOOH and γ-FeOOH, with and without chromium. These ferric oxyhydroxide powders were prepared from aqueous solutions containing iron and chromium ions. Radial structural functions for iron obtained by Fe K edge EXAFS spectra showed that the linkage of structural units formed by FeO6 octahedra in γ-FeOOH is distorted by chromium addition, while such distortion in α-FeOOH is not clearly detected. On the other hand, Cr K edge EXAFS spectra showed that the local structure around chromium does not necessarily correspond to the local structure around of iron, which is observed by Fe K edge EXAFS spectra. This suggests that the structural units containing iron and chromium are heterogeneously distributed in these ferric oxyhydroxides. The local structural information was discussed coupled with morphological features of these ferric oxyhydroxides observed by TEM. [Copyright &y& Elsevier]

A two-compartment photoelectrochemical cell consisting of a CdS photoanode immersed in aqueous sulfide solution, Nafion membrane, platinum cathode and sulfuric acid solution as the dark-compartment electrolyte was constructed. The effects of the concentrations of the electrolytes, membrane surface and cathode materials on the performance of the cell were studied to reach high quantum yield of hydrogen production. Under optimized conditions, light to hydrogen conversion efficiency up to 12% was observed under sun light illumination. [Copyright &y& Elsevier]

Nanocrystalline NiFe2O4 spinel ferrites with various grain sizes have been synthesized by ball milling the bulk NiFe2O4. The average grain sizes were estimated from the X-ray line broadening of the (3 1 1) reflection. The Ne´el temperatures of NiFe2O4 for various grain sizes were determined by magneto thermogravimetric method. The magnetic behaviour has been explained by combining the effects of changes in cation distribution on milling and finite size scaling. The shift in B–H loops has been correlated to the surface spin effects. The high coercivities observed here may be due to high anisotropies of the milled samples. The Hopkinson peak observed just below the Ne´el temperature has been explained by the mathematical formalism given by the Stoner Wohlfarth model. [Copyright &y& Elsevier]