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11.
Yu. L. Frolov I. V. Guchik V. A. Shagun A. V. Vashchenko 《Journal of Structural Chemistry》2005,46(6):979-984
Models of alkali metal hydroxide-water-dimethylsulfoxide superbasic media have been constructed using Hartree Fock and DFT (B3LYP) quantum chemical methods; the structure and energies of anion complexes are considered. The hydroxide anion in the models is stabilized as complexes of OH?·H2O and OH?· 2H2O types. 相似文献
12.
利用软嵌式粉末电极技术研究了Y(OH)3包覆对球形Ni(OH)2电化学性能的影响. 循环伏安结果表明, 在球形Ni(OH)2的氧化过程中存在Ni(Ⅲ)和Ni(Ⅳ)的两步氧化反应, 产生的Ni(Ⅳ)不稳定, 能分解产生NiOOH和氧气, 所以可将Ni(Ⅲ)→Ni(Ⅳ)看作副反应. Y(OH)3包覆层对Ni(OH)2氧化过程后期的副反应, 特别是Ni(Ⅲ)→Ni(Ⅳ)具有较好的抑制作用. 由包覆后的Ni(OH)2制成的模拟电池表现出很好的高温性能, 在1C充放电条件下, 当Y的摩尔分数为1.61%时, 在60 ℃时所对应的容量保持率可达到25 ℃的92.7%; 当Y的摩尔分数仅为0.55 %时, 在60 ℃时所对应的质量比容量也可达到241.3 mA·h/g. 相似文献
13.
Titanosilicates with complete or partial substitution of Ge or Nb in the framework and having the mineral pharmacosiderite topology were hydrothermally prepared and their ion-exchange properties towards Cs were studied for Ti/Ge/Si, Ti/Si, Nb/Ti/Si and pure Ge phases. The basis for the differences in the ion exchange properties measured as distribution coefficients (Kd) for these materials are detailed via structural characterization using the Rietveld refinement technique on the X-ray powder diffraction data. The differences in affinity towards Cs+ result either from the degree of hydration of the exchanger resulting in different coordination environments or the position of cesium ion in the eight-ring channel. 相似文献
14.
trans-RhCl(CO)(TPPTS)2 (TPPTS=tris(m-sulfonatophenyl)phosphine) has been intercalated into Zn-Al layered double hydroxides (LDHs) by the method of ion exchange. The structure, composition and thermal stability of the composite material have been characterized by powder X-ray diffraction, Fourier transform infrared and 31P solid-state magic-angle spinning nuclear magnetic resonance spectroscopy, elemental analysis, thermogravimetry, and differential thermal analysis. The geometry of trans-RhCl(CO)(TPPTS)2 was fully optimized using the PM3 semiempirical molecular orbital method, and a schematic model for the intercalated species has been proposed. The thermal stability of trans-RhCl(CO)(TPPTS)2 is significantly enhanced by intercalation, which suggests that such materials may have prospective application as the basis of a supported catalyst system for the hydroformylation of higher olefins. 相似文献
15.
Determination of trace elements in biological materials using tetramethylammonium hydroxide for sample preparation 总被引:1,自引:0,他引:1
Patrícia Martins Dirce Pozebon Valderi L. Dressler Gisele A. Kemieciki 《Analytica chimica acta》2002,470(2):62-204
A method to prepare milk powder, bovine liver and bovine muscle samples for analysis by electrothermal atomic absorption spectrometry (ETAAS) is proposed. Samples are mixed with a small amount of tetramethylammonium hydroxide (TMAH) and a stable and homogeneous slurry is produced in ca. 2 h with heating at 60–70 °C. After such sample preparation and dilution with water, trace elements are determined in certified reference materials. Pyrolysis and atomisation temperatures are optimised for each element, and several modifiers are investigated. External calibration is used for every analyte. Limits of detection (LODs), precision and accuracy are reported for Cd, Pb, Ni, Cr, Cu and Ag and compared with those obtained after conventional acid digestion. The main advantages of the proposed method are the simplicity of sample preparation and the longer lifetime of the graphite tube. 相似文献
16.
17.
Effects of polystyrene-encapsulated magnesium hydroxide on rheological and flame-retarding properties of HIPS composites 总被引:1,自引:0,他引:1
In this study, polystyrene (PS)-encapsulated magnesium hydroxide (Mg(OH)2) was successfully prepared by in situ polymerization of styrene on the surface of Mg(OH)2 in a high-speed mixer. A large amount of PS chemically bonded on Mg(OH)2 surface was confirmed by means of FT-IR, TGA and SEM. A series of composites of high impact polystyrene (HIPS) were prepared by melt blending in a co-rotating twin-screw extruder. The effects of PS-encapsulated filler on the properties of HIPS composites were studied by SEM, rheology and combustion tests (horizontal burning tests and cone calorimetry). The dispersion and adhesion patterns of PS-encapsulated Mg(OH)2 in HIPS matrix were investigated through FT-IR and SEM. The experimental results demonstrated that comparing to the composites containing untreated filler, the rheological and flame retardant properties of those containing PS-encapsulated filler were found to be significantly improved. This improvement is mostly attributed to a better dispersion of the encapsulated filler and a strong adhesion between the filler and matrix. 相似文献
18.
19.
Igor Djerdj Georg Garnweitner Markus Niederberger 《Journal of solid state chemistry》2007,180(7):2154-2165
The preparation of lanthanum hydroxide and manganese oxide nanoparticles is presented, based on a nonaqueous sol-gel process involving the reaction of La(OiPr)3 and KMnO4 with organic solvents such as benzyl alcohol, 2-butanone and a 1:1 vol. mixture thereof. The lanthanum manganese oxide system is highly complex and surprising results with respect to product composition and morphology were obtained. In dependence of the reaction parameters, the La(OH)3 nanoparticles undergo a shape transformation from short nanorods with an average aspect ratio of 2.1 to micron-sized nanofibers (average aspect ratio is more than 59.5). Although not directly involved, KMnO4 plays a crucial role in determining the particle morphology of La(OH)3. The reason lies in the fact that KMnO4 is able to oxidize the benzyl alcohol to benzoic acid, which presumably induces the anisotropic particle growth in [0 0 1] direction upon preferential coordination to the ±(1 0 0), ±(0 1 0) and ±(−110) crystal facets. By adjusting the molar La(OiPr)3-to-KMnO4 ratio as well as by using the appropriate solvent mixture it is possible to tailor the morphology, phase purity and microstructure of the La(OH)3 nanoparticles. Postsynthetic thermal treatment of the sample containing La(OH)3 nanofibers and β-MnOOH nanoparticles at the temperature of 800 °C for 8 h yielded polyhedral LaMnO3 and worm-like La2O3 nanoparticles as final products. 相似文献
20.
Chen Xiao-Ming Wu Yu-Luan Tong Ye-Xiang Sun Ziming David N. Hendrickson 《Polyhedron》1997,16(24):1041
A novel tetranuclear terbium(III) complex [Tb4(OH)4(pybet)6(H2O)8][Tb4(OH)4(pybet)6(H2O)7 (NO3)](ClO4)14·6H2O has been synthesized and shown by X-ray crystallography to have a cubane-like Tb4(μ3-OH)4(μ2-carboxylato-O,O′)6 core. The ligand pybet is pyridinoacetate, C5H5+N-CH2CO2−. Magnetic susceptibility data were measured for this Tb4 complex in the range of 2.0–320 K and in fields of 1.0 G to 50.0 kG. It is concluded that either there is very weak antiferromagnetic exchange interaction (J = −0.015 cm−1) or there is a small crystal-field splitting of the 7F6 TbIII ground state. 相似文献