We previously synthesized new nanocomposites that have clays uniformly dispersed in a nylon-6 matrix. Observation under the transmission electron microscope showed these clays to be a 1-nm-thick, 100-nm-wide layered filler. Recently, we have succeeded in making a threedimensional observation of the cross section of the nanocomposites subjected to oxygen plasma treatment, using a scanning electron microscope. The observation revealed a novel structure, in which the clay layers stood perpendicularly to the nylon surface, resemblin a vertical cliff. We named these layers a "nano wall".

Silicon-carbon (Si-C) composites were formed by mixing layered polysilane with sucrose, and then sintering. The Si-C composites had a unique form, which consisted of Si plates coated onto carbon particles. These composites were completely different from other Si-C composites made from silicon powder, which consist of carbon-coated silicon particles. Electrodes consisting of Si-C composites made from layered polysilane had a high capacity and a high capacity retention compared to layered polysilane electrodes, because the layered polysilane attached to carbon particles had a higher conductivity than a simple mixture of layered polysilane and carbon powder.

The ionomers distributed on carbon particles in the catalyst layer of polymer electrolyte fuel cells (PEFCs) govern electrical power via proton transport and oxygen permeation to active platinum. Thus, ionomer distribution is a key to PEFC performance. This distribution is characterized by ionomer adsorption and deposition onto carbon during the catalyst-ink coating process; however, the adsorbed and deposited ionomers cannot easily be distinguished in the catalyst layer. Therefore, we identified these two types of ionomers based on the positional correlation between the ionomer and carbon particles. The cross-correlation function for the catalyst layer was obtained by small-angle neutron scattering measurements with varying contrast. From fitting with a model for a fractal aggregate of polydisperse core–shell spheres, we determined the adsorbed-ionomer thickness on the carbon particle to be 51 Å and the deposited-ionomer amount for the total ionomer to be 50%. Our technique for ionomer differentiation can be used to optimally design PEFC catalyst layers.

Textured ¡-alumina ceramics were prepared by mixing different ratios of three-sized plate-like ¡-alumina particles and fine equiaxed particles without the use of sintering aids. The plate-like particles have developed a-b planes and were incorporated as an aligned template. Mixed powders were formed into a green sheet using a doctor blade technique and sintered under various conditions (temperature, duration and atmosphere). The development of microstructure and texture in the sintered bodies was examined and correlated with the preparation conditions. The addition of plate-like particles to the fine equiaxed powder suppressed densification and grain growth during sintering. The plate-like particles tend to grow with a lower aspect ratio at high temperatures, especially under vacuum sintering conditions. The addition of 30% plate-like particles produced sintered bodies with the highest uniaxial ©001ª orientation, but with residual porosity. The addition of 5% plate-like particles resulted in sintered bodies with almost full density but texture development was inferior to that of 30%. The vacuum-sintered specimens with larger amounts of platelets exhibited pseudo-isotropic grain growth and high-to-medium uniaxial ©001ª orientation, which suggests that anisotropic grain growth is not essential to achieve a high degree of orientation.

No abstract