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991.
S. V. Kolotilov A. V. Shvets N. V. Kas’yan 《Theoretical and Experimental Chemistry》2006,42(5):271-276
It was shown that the sorptive capacity for hydrogen in composites based on MCM-41 molecular sieves and nanoparticles of the
oxides of 3d metals or the metals themselves at 77 K and 1 atm is determined both by the surface area and by the volume of
the micropores of the samples and does not depend on the nature of the 3d metal (Ni, Co, Cu) or its degree of oxidation.
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 5, pp. 265–270, September–October, 2006. 相似文献
992.
CAI Wen-Bin WAN Yong-Qin LIU Hou-Tian ZHOU Wei-FangDepartment of Chemistry Fudan University Shanghai China 《中国化学》1996,14(2):138-146
The reduction processes of anodic PbO2 films formed on Pb-Sb alloys in 4.5mol·dm-3 H2SO4 solution at 1.4 V(vs.Hg/Hg2SO4) for 1 h have been investigated by pho-tocurrent method,chronoamperometry,linear sweep voltammetry as well as X-ray diifractornetry.It was found that the reduction of most of the β-PbO2 and part of the α-PbO2 to PbSO4 can be completed within I s between 0.9 V and 1.0 V(vs.Hg/Hg2SO4) and proceeds much faster than that of the remaining a-PbO2 into photoactive α·PbOx (1相似文献
993.
J. Madarász G. Pokol C. Novák F. Tamarit Cobos S. Gál 《Journal of Thermal Analysis and Calorimetry》1992,38(3):445-454
Thermal decomposition and hydrothermal reactions of aluminum oxides and hydroxides were studied. The starting material was gibbsite pretreated by grinding in different ways. Sixteen kinetic models were fitted and the rate constants were estimated at different temperatures. Mechanical activation of the starting gibbsite had an effect on the reactivity of samples in several subsequent reactions.A new quantity, the relative residual variance is defined for comparison of different linearized models, and it is proposed as a criterion of fit. This was applied in making statistics in order to find the well-fitting models.
Zusammenfassung Es wurden die thermische Zersetzung und hydrothermische Reaktionen von Aluminiumoxiden und -hydroxiden untersucht. Das Ausgangsmaterial war Gibbsit, welches durch Zerkleinern auf verschiedene Weise vorbereitet wurde. Es wurden sechzehn kinetische Modelle angewendet und bei verschiedenen Temperaturen die Gesch-windigkeitskonstanten geschätzt. Die mechanische Aktivierung des Ausgangsmateriales Gibbsit beeinflu\t die Reaktivität der Proben in einigen Folgereaktionen.Für den Vergleich verschiedener Linearisationsmodelle wurde eine neue Grö\e, die relative Restvarianz definiert, die als Kriterium für die Anpassungsgüte vorgeschlagen wird. Dies wurde bei statistischen Untersuchungen angewendet, um die bestangepa\ten Modelle zu finden.相似文献
994.
Preparation and Structure of Niobium Tungsten Oxides (Nb,W)17O47 with Mixed Valency The formal substitution of 2Nb5+ by Nb4+ or W4+, respectively, and W6+ leads to tungsten niobium oxides (Nb,W)17O47 with mixed valency. The phases Nb8-nW9+nO47 with n = 1 to 5 could be obtained by heating (1 250°) mixtures of NbO2 or WO2, respectively, with Nb2O5 and WO3. The products crystallize with the structure of Nb8W9O47. This is proved by X-ray powder diffraction and transmission electron microscopy. A further decrease of the Nb-content results in two-phase products. 相似文献
995.
N. Deligne 《Journal of solid state chemistry》2007,180(7):2026-2033
New hybrid organic-inorganic materials based on group 5 elements and a well-defined polymeric matrix have been prepared and used as precursors for Nb-Ta and Nb-Mo mixed oxides. In this non-conventional but easily accessible route to multimetallic oxides, a copolymer of N,N-diallyl-N-hexylamine and maleic acid was synthesised and used as matrix to stabilise inorganic species generated in solution from (NH4)6Mo7O24·4H2O, NH4VO3, (gu)3[Nb(O2)4] and (gu)3[Ta(O2)4]. Solid-state studies indicate that the homogeneity of the blends can be kept up to about 0.5 mol NbV and TaV and 0.25 mol VV per mol of repeat units of the copolymer. The calcination conditions of these homogeneous hybrid precursors were optimised to produce Nb-Mo, Nb-Ta and Nb-V oxides. While the thermal treatment of the Nb-V hybrid blends led only to a mixture of different phases, the characterisation of the final phases by X-ray diffraction (XRD) proved the formation of pure Nb2Mo3O14 and showed that Nb-Ta oxides could be synthesised as single phases corresponding to a continuous series of solid solutions. 相似文献
996.
A. M. Nazarov E. M. Chainikova S. L. Khursan A. N. Ryzhkov R. L. Safiullin V. D. Komissarov 《Russian Chemical Bulletin》1998,47(7):1292-1295
The kinetics of self-termination of benzophenone oxide (BPO) in the liquid phase was studied by flash photolysis. The extinction
coefficient of BPO (ε) was found to be virtually independent of the solvent nature, ε=(1.9±0.1)·103 L mol−1 cm−1. The rate constant of the BPO self-temination increases from 1.8·107 (MeCN) and 7.4·107 (C6H6) to 1.5·109 (n-decane) and 2.0·109 L mol−1 s−1 (n-pentane) at 293±2 K. Solvation of BPO promotes a polar state of the molecule in MeCN and C6H6. In nonpolar hydrocarbons, a great contribution is made by the biradical structure resulting in an increase in the rate constant
and a shift of the absorption maximum to the long-wave region (from 410 nm in MeCN to 425 nm inn-pentane). In solutions of benzene and acetonitrile, benzophenone oxide reacts with the parent diazo compound with a rate
constant of (2–4)·105 L mol−1 s−1 (293±2 K) along with the self-termination.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1329–1332, July, 1998. 相似文献
997.
Luisa F. Cueto Gustavo A. Hirata Eduardo M. Sánchez 《Journal of Sol-Gel Science and Technology》2006,37(2):105-109
The effect of electrochemical reduction of CO2 on the structure and morphology of titanium(IV) oxide thin films was examined after a fixed-potential bulk electrolysis process.
Films deposited on ITO (Indium-Tin Oxide) substrates were used as the working electrodes and 1-butyl-3-methylimidazolium tetrafluoroborate
([BMIm][BF4]) as solvent and as supporting electrolyte. Grazing incidence X-ray diffraction analysis performed before and after the electrolysis
process indicated no microstructural changes of the anatase films. X-ray photoelectron spectroscopy revealed peaks associated
with adsorbed carbonate ions at 288 eV and CO2 species at 293 eV, whereas Ti2p peaks displacements for CO2-saturated TiO2/ITO surfaces in [BMIm][BF4] revealed chemical bonding effects. Auger electron spectroscopy revealed a high carbon content on CO2-exposed films, and suggested a strong chemisorption of CO2 and CO32− species on the TiO2/ITO surface in [BMIm][BF4] solvent system. A significant decrease in carbon content after bulk electrolysis indicated that the CO2 electroreduction process is not controlled by either diffusion or by adsorption of CO2 on the TiO2/ITO electrode surface. 相似文献
998.
V. A. Ogurtsov O. A. Rakitin Yu. A. Strelenko N. V. Obruchnikova L. I. Khmel'nitskii 《Russian Chemical Bulletin》1993,42(4):706-708
Interaction of aromatic nitrile oxides with bis-trimethylsilylthiodiimide results in 2-amino-4-aryl-1,2,3,5-oxathiadiazoles, the first representatives of a new class of heterocyclic compounds.For Part 2, see ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 742–743, April, 1993. 相似文献
999.
用XPS测定了LnCu2O4(Ln=Gd, Nd)的内层和价层电子能谱,观察到LnCu2O4中稀土金属的3d电子结合能比相应的稀土金属简单氧化物的3d结合能低0.8~0.9 eV,而Cu的2p电子结合能比CuO的高0.4~0.5 eV,因此推断在LnCu2O4的Ln-O-Cu链中存在Cu→O→Ln电荷转移.XPS分析还表明LnCu2O4的Cu原子上有较低的电荷密度,但不存在混合价态.此外,通过比较价电子能谱,发现NdCu2O4的Ln 4f Cu 3d O 2p价带中心比GdCu2O4的价带中心向Fermi能级移近了3.4 eV,而且NdCu2O4的价带谱更窄. 相似文献
1000.
Quasi two-dimensional copper oxides derived from La1·8Sr0·2CuO4 by substitution of La, Sr or Cu show highT
c
superconductivity.
Contribution No. 421 from the Solid State and Structural Chemistry Unit. 相似文献