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81.
An improved method is described for the sol–gel preparation of PLZT thin layers in the perovskite structure. The method uses a PbO cover coat. Details are reported for the sol-gel processing route and heat-treatment conditions. Through use of this method it is possible to prepare singlephase perovskite material with improved properties. The deleterious effect of additional phases—which are not present when a PbO cover coat is used—is attributed to Pb loss from the surface during thermal processing. Examples are given for PLZT thin layers integrated on Si with and without a PbO cover coat. The dielectric and ferroelectric properties were always found to be superior for coated structures. 相似文献
82.
Plasma-deposited polycrystalline Si films [or microcrystalline Si (μc-Si) films] produced by plasma enhanced chemical vapor deposition (PECVD) have attracted considerable attention as novel, low-cost and stable materials for the photovoltaic i-layer in p–i–n junction thin-film solar cells. The μc-Si films prepared under various deposition conditions show widely various microstructures, from a crystalline–amorphous mixed state to an almost perfect crystalline state, with different crystallographic orientations. These structural changes directly influence the carrier transport properties that play a dominant role in determining photovoltaic performance. Furthermore, obtaining a uniform built-in electric field throughout the i-layer is a crucial issue for achieving excellent photovoltaic performance. To obtain a uniform electric field, the following terms should be required for the i-layer: ‘truly’ intrinsic characteristic (or not n-type characteristics) as well as structural uniformity in the growth direction without an incubation layer. Here, structural properties of μc-Si for achieving truly intrinsic characteristics are reviewed with an emphasis on collations with the crystalline volume function and the degree of (2 2 0) crystallographic preferential orientation in the crystalline phase. In addition, we reviewed a growth mechanism for the μc-Si film that is actually used in the photovoltaic i-layer in highly efficient solar cells: hybrid-phase growth consisting of conventional vapor-phase growth at the surface and the solid-phase crystallization that simultaneously occurs in the film. That growth is very effective in producing structural uniformity along the growth direction and for formation of crystallites directly on the underlying doped layer. 相似文献
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Free radicals generated in stretched and ground poly [p-(2-hydroxyethoxy) benzoic acid] (PEOB) were studied by e.s.r. spectroscopy in an effort to isolate those formed by main chain scission. PEOB fibres stretched at ?86°C in a dry nitrogen atmosphere gave an asymmetric spectrum, which had patterns characteristic of both phenoxy and peroxy radicals in addition to some unknown peaks. The shape of the spectrum changed with increasing temperatures, finally becoming identical to that of phenoxy radicals at room temperature. The phenoxy radical was observed in all PEOB films ground or γ-irradiated in liquid nitrogen. In some cases a small peak of peroxy radical was observed. Theoretical spectra calculated for possible radical species or combinations of them were compared with those observed. No direct evidence was observed of the formation of alkyl type and radicals which were assumed to be formed with phenoxy radicals upon main chain rupture of PEOB. However, the relatively unstable peroxy radical observed in these experiments is thought to arise from them. 相似文献
86.
Mutsuto Kawahara Toshihiko Miwa 《International journal for numerical methods in engineering》1984,20(7):1193-1210
To estimate wave motion, the finite element method is presented based on the linear interpolation function and two-step explicit numerical integration in time. For the determination of free surface position, the two-step scheme based on the Eulerian technique is usefully employed. Travel and run-up of solitary wave have been analysed and compared with the analytical solution. Both results are reasonably well in agreement. This method is applied to estimate the wave force on the practical breakwater to show the validity of the method. 相似文献
87.
Toshihiko Nishida Yoshikazu Hanaki Taketoshi Nojima Giuseppe Pezzotti 《Journal of the American Ceramic Society》1995,78(11):3113-3116
A simple procedure for measuring the R -curve properties of ceramics by a stable fracture test in three-point bending is described. As a typical case, data are displayed for a Si3 N4 material toughened by the presence of acicular grains in situ grown during the sintering process. The fracture mechanics specimen was a single-edge double-notched beam (SEDNB), whose notch was sharpened to a radius of <10 μm in order to reduce the amount of elastic energy stored at its root prior to crack extension. Furthermore, a stabilizer, specially designed for the bending geometry, was used to control crack stability. During stable extension, the crack could be easily arrested at selected locations of the load-displacement curve, the load quickly released, and the stable crack extension directly measured by the die-penetration technique. The crack resistance, K R , of the material was calculated from the measured crack extent and the onset load value before unloading. This method enabled us to precisely monitor the critical load value at which the load-displacement curve deviated from linear behavior, as well as crack extensions from a few tens of micrometers to about 1 mm. As an application of this method, the fracture resistance of a Si3 N4 material with rising R -curve behavior was measured and found to increase from about 5.5 to 9.0 MPaμm1/2 within a 0.8-mm extension. 相似文献
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Toshihiko Sakayama Tetsuo Hara Tsuneo Imai 《Bulletin of Engineering Geology and the Environment》1982,26(1):309-313
Bulletin of Engineering Geology and the Environment - To explore the shallow structure of the ground, the combined use of ground probing radar and electric profiling was tested. As a result, it is... 相似文献