Nanostructured Materials最新文献

γ-irradiation method was used for the first time to prepare spherical assemblies of 10 × 50nm CdS nanofibers in poly(vinyl acetate) with diameter of 120nm. The irradiation reaction between cadmium chloride and carbon disulfide, and the polymerization of monomer vinyl acetate occur in the one-spot heterogeneous system, leading to the formation of spherical assemblies of semiconductor in polymer and the resulting CdS nanofibers with a good crystallinity. The preparation was done at room temperature and ambient pressure.

Attrition milled, nanostructured iron-based powders were compacted at temperatures less than one half the melting temperature and at pressure in excess of 1GPa and resulted in full dense samples from which macroscopic properties could be determined. The use of modest compaction temperatures resulted in (1) reducing the mechanical induced lattice strain, (2) producing interparticle bonding by grain boundary diffusion, and (3) limiting grain growth. The high compression stress resulted in deforming the milled particles into a fully dense compact. Hall-Petch relationships for the compacts were consistent with data from previous studies.

The importance of the internal interfaces between structural elements and their surroundings for the electronic properties of nanostructured materials is stressed by giving a brief overview of recent optical experiments on several different kinds of cluster-matter: (1) The Mie-absorption of silver nanoparticles embedded in various solid matrix materials was used to obtain information about static and dynamic charge transfer in the interlayers and their impact on the plasmon dephasing lifetime. (2) Effects of chemical surface reactions are demonstrated for silver clusters reacting with oxygen, sulphur and tripenylphosphine. (3) The occurrence of structural and electronic phase transitions during hydrogenation of yttrium (which is well-known for extended matter) is demonstrated for the first time for clusters. (4) Non-linear optical bi-stability is shown for silver-coated CdS-clusters. This paper was presented at The Fourth International Conference on Nanostructured Materials, NANO ‘98, July 1998, Stockholm/Sweden.

The exponential increase in areal density of recording of magnetic storage devices has reduced the recorded bit size to nano length scale. This has profound implications on all aspects of the storage system including recording device modeling, materials, fabrication, metrology, characterization, and tribology of the head-disk interface. In this paper, the impact of nanotechnology in extending the data storage device storage systems is explored with an emphasis on the fabrication and characterization of nanolayers and structures.

The shapes of Mössbauer spectra of coarse-grained annealed armco iron and submicrocrystalline (SMC) iron with a grain size of 0.22 μm were compared. The SMC was made from the armco iron by pressure shear and subsequent annealing at 420 °C. We intended to separate an additional subspectrum, which appears as a result of the grain refinement. That subspectrum was attributed to grain-boundary atoms or the “grain-boundary phase” (GBP). The volume fraction of that phase was determined. On the average, the GBP interatomic spacing was suggested to be 1% larger than that of the grain phase (GP) and the presence of considerable compressive stresses in the GBP were deduced. A possible reason for the satellite subspectrum appearing after the grain refinement was that it was attributed to a sudden change in the fundamental characteristics of the solid at a certain critical value of the lattice parameter, which varies continuously in going from the geometrical boundary to the grain center.