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81.
Takamasa Ishigaki Shigeru Yamauchi Junichiro Mizusaki Kazuo Fueki Hiroyuki Naito Tatsuya Adachi 《Journal of solid state chemistry》1984,55(1):50-53
The tracer diffusion coefficient, , of oxide ions in LaFeO3 single crystal was determined over the temperature range of 900–1100°C by the gas-solid isotopic exchange technique using 18O as a tracer. For the determination of , the depth profile of 18O was measured by means of a secondary ion mass spectrometer (SIMS). The surface exchange reaction was found to be slow and the surface exchange rate constant, k, was determined together with . It was found that at 950°C is proportional to P?0.58O2, where PO2 is an oxygen pressure. The vacancy mechanism was determined for the diffusion of oxide ions from the PO2 dependence. The vacancy diffusion coefficient, DV, for LaFeO3 was nearly the same as that for LaCoO3 at the same temperature. The activation energy for migration of oxide ion vacancies was 74 kJ · mole?1 for both oxides. 相似文献
82.
Takamasa Nonaka Rikiichi Tagawa Haruo Nishida Hiroaki Egawa 《Journal of polymer science. Part A, Polymer chemistry》1984,22(12):3815-3825
Water-solube polymer (PST) containing triethylenetetramine side chain was prepared by the amination of chloromethylated polystyrene with triethylenetetramine in 1,4-dioxane. The polymerization of vinyl monomers was carried out in the water–organic solvent system containing PST and a very small amount of peroxide. The polymerization of methyl methacrylate proceeded smoothly in the presence of both peroxide and PST. It was found that the polymerization was initiated with the radicals generated by the interaction between hydroperoxide and amino groups of PST. 1,4-Dioxane hydroperoxide showed a high activity for the polymerization of methyl methacrylate. The maximum rate of the polymerization was observed at 60°C and in an approximately neutral solution. The addition of suitable amount of Cu(II) accelerated the polymerization of methyl methacrylate. The selective polymerization of vinyl monomers was observed in this system. 相似文献
83.
Masayuki Kitamura Noritaka Usami Takamasa Sugawara Kenrato Kutsukake Kozo Fujiwara Yoshitaro Nose Toetsu Shishido Kazuo Nakajima 《Journal of Crystal Growth》2005,280(3-4):419-424
The floating zone technique was employed to grow multicrystalline Si with controlled grain boundary configuration. Purposely designed bi-crystals were utilized as seed crystals to investigate the effect of the tilt angle from the perfect twin boundary on the growth behavior. When the growth was initiated from a bi-crystal with a Σ3 twin boundary, no particular change took place on the grain boundary configuration during growth. On the other hand, the decrease of the tilt angle during growth was observed when the growth was initiated from a bi-crystal with a tilted boundary from Σ3. This was accompanied by the appearance of new crystal grains. The reduction of the total interface energy would be a possible driving mechanism for this phenomenon. 相似文献
84.
Naotoshi Nakashima Takeshi Tokunaga Yuko Nonaka Takashi Nakanishi Hiroto Murakami Takamasa Sagara 《Angewandte Chemie (International ed. in English)》1998,37(19):2671-2673
Two reversible one-electron transfers are observed for an electrode device made from C60 and an artificial lipid (see schematic drawing). Cyclic voltammetric studies reveal that the redox couples are unchanged even after 50 cycles, thus indicating that the C60 radical monoanion and the C60 dianion generated in aqueous solution are very stable. 相似文献
85.
Kunio Hiroi Fumiko Kato Takamasa Oguchi Shinya Saito Takanori Sone 《Tetrahedron letters》2008,49(22):3567-3569
α-Allenylcyclopropanedicarboxylates, for which a novel synthetic method has been devised by conjugate addition of a copper hydride (Stryker) reagent to α-cyclopropylpropargylic esters, have been newly found to be smoothly converted to methylenecyclopentene derivatives under mild reaction conditions by further treatment with the copper hydride reagent. The mechanistic pathway is discussed. 相似文献
86.
Atsushi Nakahira Hidezumi Nagata Takamasa Onoki Yuki Yamasaki 《Research on Chemical Intermediates》2008,34(4):347-352
Synthesis of mesoporous MCM-type bulks prepared by hydrothermal hot-pressing (HHP) method using MCM-type mesoporous powder
was attempted. Scanning electron microscopy (SEM), bulk density measurement, N2 adsorption-desorption isotherms and formaldehyde adsorption test have been employed to characterize the bulky products. As
a result, we succeeded in preparing a dense and strong mesoporous bulks with high BET over 1000 m2/g through the hydrothermal hot-pressing method under appropriate conditions. 相似文献
87.
Tomoyuki Nakano Yoshitaka Kawakami Tadashi Ishigaki Mineo Sato 《Journal of luminescence》2009,129(12):1654-1657
Alkaline earth silicates, which comprise a host material doped with rare-earth minerals, show excellent luminescence properties with various crystal structures and high stability. From results of this study, we report luminescence properties of Ba9Sc2Si6O24:Eu2+ and Ba9Sc2+δSi6O24−3δN3δ:Eu2+ as a novel alkaline earth silicate and silicon oxynitride phosphors for white LEDs. Using a conventional solid-state reaction, Ba9Sc2Si6O24:Eu2+ samples were synthesized and Ba9Sc2+δSi6O24−3δN3δ:Eu2+ samples were obtained by nitrization of Ba9Sc2+δSi6O24:Eu2+. The samples can be excited by blue light, exhibiting green (Ba9Sc2Si6O24:Eu2+) and yellow (Ba9Sc2+δSi6O24−3δN3δ:Eu2+) efficiently, which are emissions for use in white LEDs essentially. 相似文献
88.
We have demonstrated the decay of spontaneous emission (SE) from AlN-GaN quantum dots (QDs) into silver surface plasmon (SP) modes in the ultraviolet at approximately 375-380 nm. Using time-resolved photoluminescence (PL), we show that the electron-hole recombination rate in AlN-GaN QDs is enhanced when SE is resonantly coupled to a metal SP mode, corresponding to the dip in the continuous-wave PL spectrum. Exciton recombination by means of silver SP modes is as much as 3-7 times faster than in normal QD SE and depends strongly on emission wavelength and thickness of the silver. 相似文献
89.
Palladium complex catalyzed carbonylation of 2-bromo-3,3,3-trifluoropropene (2-Br-TFP) with ureas afforded 5-trifluoromethyl-5,6-dihydrouracils in moderate to good yields, which were converted into 5-trifluoromethyluracils in nearly quantitative yields. 相似文献
90.