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81.
Shinichi Komaba Naoaki Yabuuchi Sachi Ikemoto 《Journal of solid state chemistry》2010,183(1):234-4419
To study crystallization process of spinel-type Li1+xMn2−xO4, in-situ high-temperature X-ray diffraction technique (HT-XRD) was utilized for the mixture consisting of Li2CO3 and Mn2O3 as starting material in the temperature range of 25-700 °C. In-situ HT-XRD analysis directly revealed that crystallization process of Li1+xMn2−xO4 was significantly affected by the difference in the Li/Mn molar ratio in the precursor. Single phase of stoichiometric LiMn2O4 formed at 700 °C. The formation of single phase of spinel was achieved at the lower temperature than the stoichiometric sample as Li/Mn molar ratio in the precursor increased. Lattice parameter of the stoichiometric LiMn2O4 at 25 °C was 8.24 Å and expanded to 8.31 Å at 700 °C, which corresponds to the approximately 3% expansion in the unit cell volume. From the slope of the lattice parameter change as a function of temperatures, linear thermal expansion coefficient of the stoichiometric LiMn2O4 was calculated to be 1.2×10−5 °C−1 in this temperature range. When the Li/Mn molar ratio in Li1+xMn2−xO4 increased (x > 0.1), the spinel phase segregated into the Li1+yMn2−yO4 (x > y) and Li2MnO3 during heating, which involved the oxygen loss from the materials. During the cooling process from 700 °C, and the segregated phase merged into Li1+xMn2−xO4 with oxygen incorporation. Such trend directly observed by in-situ HT-XRD was supported by thermal gravimetric analysis as reversible weight (oxygen) loss/gain at higher temperature (500-700 °C). 相似文献
82.
We report an electron-probe microanalysis of a hologram recorded in a silica-nanoparticle-dispersed photopolymer film. We used S and Si atoms as label elements to identify formed polymer and nanoparticle species, respectively. It is found that the periodic density distributions of S and Si atoms are out of phase with each other, indicating that those of the formed polymer and nanoparticles are out of phase each other. This result shows decisive evidence of the mutual diffusion of monomer molecules and silica nanoparticles in the film under holographic two-beam interference exposure. 相似文献
83.
Naoaki Yamasaki Junzo Masamoto 《Journal of polymer science. Part A, Polymer chemistry》2004,42(3):520-533
Novel reactions between trioxane and ethylene oxide were discovered, and three novel cyclic formals were isolated and identified. These novel cyclic compounds clarified the initiation mechanism of the copolymerization of trioxane and ethylene oxide. This type of reaction was not limited to the reaction between trioxane and ethylene oxide but was also generalized to the reaction between the cyclic formal and ethylene oxide. Although an NMR method for analyzing the ethylene oxide sequences of the acetal copolymer from trioxane and ethylene oxide has not yet been established, the three newly found novel cyclic compounds, composed of 1 mol of ethylene oxide and 1 mol of trioxane, 2 mol of ethylene oxide and 1 mol of trioxane, and 3 mol of ethylene oxide and 1 mol of trioxane, were useful for analyzing the ethylene oxide sequences. These compounds gave only one consecutive oxyethylene unit, two consecutive oxyethylene units, and three consecutive oxyethylene units in three consecutive oxymethylene units, respectively, and gave different 1H NMR spectra for each oxyethylene unit. Considering these data, we synthesized three polymeric model compounds that had one consecutive oxyethylene sequence, two consecutive oxyethylene sequences, and three consecutive oxyethylene sequences in an oxymethylene main chain. By a linear combination of the 1H NMR spectrum of each oxyethylene unit of the three polymeric model compounds, we succeeded in determining the ethylene oxide sequences by the 1H NMR method for the copolymer from trioxane and ethylene oxide. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 520–533, 2004 相似文献
84.
Kiriyama H Mori M Nakai Y Yamamoto Y Tanoue M Akutsu A Shimomura T Kondo S Kanazawa S Daido H Kimura T Miyanaga N 《Optics letters》2007,32(16):2315-2317
We describe a compact, reliable, high-power, and high-contrast noncollinear optical parametric chirped-pulse amplifier system. With a broadband Ti:sapphire oscillator and grating-based stretching and compression, the chirped pulses are amplified from 0.1 nJ to 122 mJ in type I beta-barium borate optical parametric chirped-pulse amplifiers with a total gain of over 10(9) at 10 Hz repetition rate. Pulse compression down to 19-fs duration achieved after amplification indicates a peak power of 3.2 TW at an average power of 0.62 W. The prepulse contrast is measured to be less than 10(-8) on picosecond time scales. 相似文献
85.
Saito N Nanjyo J Taneda Y Shiokawa Y Tanimoto M 《Rapid communications in mass spectrometry : RCM》2007,21(16):2654-2662
We report a new type of mass spectrometry based on a time-of-flight mass spectrometer combined with an ion attachment ionization technique (IA-TOF). In contrast to electron ionization mass spectra, IA-TOF mass spectra are not complicated by peaks due to fragmentation of the molecular ion; the adduct ion formed in IA does not fragment. We developed a tabletop IA-TOF system and evaluated its performance by analyzing specimens originally in the gas, liquid, and solid phases. We obtained fragment-free spectra covering a mass range up to m/z 3400 with a mass resolution of about 4700. Our IA-TOF system realizes accurate and versatile real-time mass spectrometry. 相似文献
86.
Hideo Kaiju Mao NishiyamaYuki Otaka Naoaki SakaguchiKazuo Shiiki 《Journal of magnetism and magnetic materials》2006
The oxidation states of Al-oxide layer and the leakage current density in coercive differential spin tunneling junctions Co/Al-oxide/Co have been investigated in order to clear the mechanism of the increasing resistance change. X-ray photoelectron spectroscopy analysis shows that the resistance change increases with decreasing unoxidized Al, which can be qualitatively explained by using first-principle band calculation based on linear-muffin-tin-orbital atomic-sphere-approximation method. The resistance change decreases with increasing leakage current density, which originates from Schottky effect. Reduction of unoxidized Al and leakage current density originating from Schottky effect is required to obtain the large resistance change in spin tunneling junctions. 相似文献
87.
The chemical behavior of 1-adamantylnitrenium ion seems to be not known much compared to 1-adamantylcarbinyl cation,2 though one example of the rearrangement of 1-adamantylnitrenium ion to 4-azahomoacamantyl ion has been reported recently by Kovacic et al in the reaction of 1-M,N-dichloroaminoadamantane with aluminum chloride.3 From our interest in the reactivity and rearrangement aptitude of 1-adamantylnitrenium ion, we investigated the reactions of various N-substituted N-chloro-1-adamantylamine derivatives with aluminum chloride. This communication deals with the preliminary results which indicated that the reactions of 1-adamantylnitrenium ion are much affected by the N-substituents and also by the solvents used. 相似文献
88.
89.
A combined preconcentration-photometric determination technique has been worked out for trace concentration of tin in fresh and sea waters. After refluxing the sample acidified to 1M HCl for 2 h, tin is preconcentrated by anion-exchange in the presence of thiocyanate and recovered by elution with dilute HNO3. Tin is then generated as stannane, caught in permanganate solution, and determined spectrpphotometrically with phenylfluorone. The results are quoted on the determination of tin in several fresh and sea waters in the order of submicrogram of tin per litre. The results for tin are in good agreement with those obtained for these samples by manganese dioxide coprecipitation-hydride generation-phenylfluorone spectrophotometric method that is also newly developed. 相似文献
90.
Proton spin-lattice relaxation rate has been measured at room temperature in the impurity-doped (CH3)4NMn(1-x)CuxCl3 for X = 0.04, 0.1 and 0.17. The result for Hz. snfc;chain-axis as a function of resonance frequency clearly shows that the spectral density of the spin fluctuations in the impure system remains to have the characteristics 1-D diffusive term (ω-), with a slower rate of the spin diffusion in accordance with the theory by Richards. The result for H⊥ chain-axis indicates, however, the existence of a singularity of the fluctuations near ω = 0. 相似文献