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71.
Molecular Dynamics Study of Atomic Structure and Diffusion Behavior in Amorphous Silicon Nitride Containing Boron 总被引:1,自引:0,他引:1
We have performed molecular dynamics simulations of amorphous Si3 N4 containing boron (Si-B-N). We have examined short-range atomic arrangements and self-diffusion constants of amorphous Si-B-N systems with various boron contents. Our simulations show that boron atoms are threefold coordinated by nitrogen atoms and that nitrogen atoms are bonded to both silicon and boron atoms in the amorphous network of Si-B-N. Also, the self-diffusion constant of nitrogen in Si-B-N is much decreased compared with that in amorphous Si3 N4 . This suggests that boron is important in decreasing the mobility of atoms in amorphous Si-B-N, which may explain the improved thermal stability of amorphous Si-B-N relative to amorphous Si3 N4 observed experimentally. 相似文献
72.
73.
Hiroyuki Kamata Shun-ichiro Ueno Naoki Sato Toshiyuki Naito 《Fuel Processing Technology》2009,90(7-8):947-951
Mercury oxidation by hydrochloric acid over the metal oxides supported by anatase type TiO2 catalysts, 1 wt.% MOx/TiO2 where M = V, Cr, Mn, Fe, Ni, Cu, and Mo, was investigated by the Hg0 oxidation and the NO reduction measurements both in the presence and absence of NH3. The catalysts were characterized by BET surface area measurement and Raman spectroscopy. The metal oxides added to the catalyst were observed to disperse well on the TiO2 surface. For all catalysts studied, the Hg0 oxidation by hydrochloric acid was confirmed to proceed. The activity of the catalysts was found to follow the trend MoO3 ~ V2O5 > Cr2O3 > Mn2O3 > Fe2O3 > CuO > NiO. The Hg0 oxidation activity of all catalysts was depressed considerably by adding NH3 to the reactant stream. This suggests that the metal oxide catalysts undergo the inhibition effect by NH3. The activity trend of the Hg0 oxidation in the presence of NH3 was different from that observed in its absence. A good correlation was found between the NO reduction and the Hg0 oxidation activities in the NH3 present condition. The catalyst having high NO reduction activity such as V2O5/TiO2 showed high Hg0 oxidation activity. The result obtained in this study suggests that the oxidation of Hg0 proceeds through the reaction mechanism, in which HCl competes for the active catalyst sites against NH3. NH3 adsorption may predominate over the adsorption of HCl in the presence of NH3. 相似文献
74.
Takanori Takeno Toshifumi Sugawara Hiroyuki Miki Toshiyuki Takagi 《Diamond and Related Materials》2009,18(5-8):1023-1027
Tribological properties of a diamond-like carbon (DLC) coating with an adhesive tungsten-containing DLC (W-DLC) layer were investigated. The coatings were deposited onto AISI316L steel substrates and Si wafers using plasma enhanced chemical vapor deposition and tungsten co-sputtering of the metal target. Methane and argon gases were used as the precursor of the coatings. In this study, three types of coatings were evaluated: DLC/W-DLC on AISI316L (DLC-1), DLC/W-DLC on Si wafer (DLC-2), and DLC on Si wafer (DLC-3). The structural characterizations were performed by transmission electron microscopy and tapping mode atomic force microscopy. At the boundary between the W-DLC layer and the AISI316L substrate, microscopic decohesion or delamination was not observed. The surface roughness of the DLC-1 coating was greater than that of the DLC-2 coating. This feature was derived from the surface roughness of the initial surface of the AISI316L substrate. Friction tests were performed using a rotation-type ball-on-flat configuration tribometer. The observed friction of the DLC-1 coating was unstable compared with the DLC-2 or DLC-3 coatings. This was due to wear debris which had risen to the friction surface resulting in unstable friction on the DLC-1 coating. During the friction studies, the top DLC layer was removed from the adhesive W-DLC layer because the adhesive strength at this part was not enough. In order to achieve the low and stable friction of the DLC coating with the W-DLC layer on AISI316L, it is necessary to improve the smoothness of the surface and the adhesion between the DLC coating and the W-DLC layer. 相似文献
75.
The catalytic activity in the polymerization of styrene has been examined using commercially available simple rare earth metal compounds such as Sm(OiPr)3, Sm(acac)3, Sm(OCOMe)3, SmI2(THF)2 or SmCl3 coupled with Et3Al or methylaluminoxane (MAO). Among these compounds, the Sm(OiPr)3/AlEt3 system shows the highest catalytic activity, especially in the presence of a minor amount of toluene at 60 °C. The random copolymerization of styrene with methyl methacrylate suggests that the present polymerization proceeds with a radical polymerization mechanism. (C5Me5)SmCl3Na(THF) and (C5Me5)SmCl3Li(THF) systems exhibit relatively low catalytic activity, even in the presence of AlEt3. © 2001 Society of Chemical Industry 相似文献
76.
Hiroshi Kominami Masaaki Kohno Yukino Matsunaga Yoshiya Kera 《Journal of the American Ceramic Society》2001,84(5):1178-1180
Silica-modified titanium oxide (S-TiO2 ) powders that have an anatase structure were synthesized via the thermal decomposition of mixtures of titanium(IV) isopropoxide (TIP) and tetramethyl orthosilicate (TMOS) in toluene at 300°C. These S-TiO2 materials had high rutile-transformation temperatures and maintained large surface areas at elevated temperatures (550°–1000°C). For example, the product that was prepared from a 9:1 TIP:TMOS mixture transformed to rutile at ∼1100°C and possessed a surface area of 160 m2 /g, even after calcination at 800°C for 1 h. 相似文献
77.
The effects of seed layers on the characteristics of rf-sputtered lead zirconium titanate thin films were investigated. Prior to sputtering, PbTiO 3 seed layers (100 nm) were deposited onto the Pt/Ti/Si and Pt/Si substrates by sol-gel (spin coating) processing method. Structure-property relation was studied as functions of substrate temperature and sputtering conditions. Special efforts were given in optimizing the deposition parameters to prepare the films in the perovskite phase without post deposition annealing. Dielectric constant and loss tangent of the films were in the range 800-950 and 0.04 -0.06, respectively. Remanent polarization and coercive field were 23.1 w C/cm 2 and 75kV/cm, respectively, for the films without PbTiO 3 seed layer, where as the corresponding quantities for in situ -deposited perovskite Pb(Zr, Ti)O 3 films on PbTiO 3 seed layer were 28 w C/cm 2 and 65 kV/cm, respectively. 相似文献
78.
Song Chen Toshiyuki Ikoma Nobuhiro Ogawa Satoshi Migita Hisatoshi Kobayashi Nobutaka Hanagata 《Science and Technology of Advanced Materials》2010,11(3)
Novel type I collagen hybrid fibrils were fabricated by neutralizing a mixture of type I fish scale collagen solution and type I porcine collagen solution with a phosphate buffer saline at 28 °C. Their structure was discussed in terms of the volume ratio of fish/porcine collagen solution. Scanning electron and atomic force micrographs showed that the diameter of collagen fibrils derived from the collagen mixture was larger than those derived from each collagen, and all resultant fibrils exhibited a typical D-periodic unit of ∼67 nm, irrespective of volume ratio of both collagens. Differential scanning calorimetry revealed only one endothermic peak for the fibrils derived from collagen mixture or from each collagen solution, indicating that the resultant collagen fibrils were hybrids of type I fish scale collagen and type I porcine collagen. 相似文献
79.
Masayuki Ohta Keitaro Kondo Masayuki Matsunaka Hiroyuki Miyamaru Isao Murata Toshiyuki Iida Kentaro Ochiai Chikara Konno 《Fusion Engineering and Design》2009,84(7-11):1446-1449
Integral benchmark experiments with DT neutrons are not always sufficient for nuclear data benchmarking in the MeV region, below 10 MeV. A neutron spectrum shifter, which will be placed between a sample and a DT neutron source, is effective to moderate DT neutrons incident to the sample. In order to estimate effects of the spectrum shifter, the ratio of the contribution of 14 MeV neutrons in the leakage neutron and gamma-ray spectra was calculated with MCNP-4C for an experimental configuration at FNS of JAEA, Japan. The calculations were carried out for a Li2TiO3 sample with a Be, D2O, or 7LiD spectrum shifter. It was found out that the Be shifter was superior to others and the Be shifter was effective to decrease the contribution of 14 MeV neutrons especially for secondary gamma-ray spectrum measurements. 相似文献
80.