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861.
V. V. Ozeryanskaya V. E. Guterman I. L. Shukaev V. P. Grigor'ev 《Russian Chemical Bulletin》1998,47(8):1481-1486
Comparative study of the regularities of the reaction and specific features of phase formation during electrochemical incorporation
of lithium from propylene carbonate solutions in intermetallic aluminum-based compounds (CuAl2, Mg2Al3, and NiAl) and pure metals (Al, Cu, Mg, and Ni) was performed. The initial stage of the process was shown to be dissolution
of lithium in the solid phase limited by diffusion for all studied substrates. Trace amounts of lithium-containing by-products,
were detected in NiAl, Ni, and Cu samples. The subsequent change in the limiting stage is related to the beginning of formation
of a new phase: metallic lithium (on Mg2Al3, NiAl, Mg, Ni, and Cu) or LiAl (on Al and CuAl2 cathodes). In the latter case, the solid-phase substitution occurs, which is formally described by the equation: CuAl2+2Li++2e→2LiAl+Cu. Thus, the specific features of phase formation on the CuAl2 electrode correspond to the highest (among three intermetallides studied) concentration of Al atoms in the crystal lattice
of the compound.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8. pp. 1525–1530, August, 1998. 相似文献
862.
Synthesis and properties of liquid crystalline polyurethanes 总被引:1,自引:0,他引:1
1,4-Bis(p-hydroxybenzoate)phenylene was prepared using 1,4-bis(trimethylsiloxy)benzene and p-hydroxybenzoyl chloride as starting materials. A series of novel 1,4-bis(p-hydroxyalkoxybenzoate)phenylene were synthesized by reaction of 1,4-bis(p-hydroxybenzoate) phenylene with 3-brompropanol and 4-bromobutanol, respectively. The liquid crystal polyurethanes were prepared
by 1,4-bis(p-hydroxyalkoxybenzoate)phenylene with MDI (p-methylene diphenylenediisocyanate) and 2,4-TDI(2,4-toluenediisocyanate), respectively. The thermotropic properties, the melting
point (T
m) and the isotropization temperature (T
i) of the synthesized polyurethanes were characterized by DSC, IR and POM. It showed that all of the polyurethane polymers
exhibited thermotropic liquid crystalline properties between 144°C and 260°C. The transition temperature (T
m and T
i) decreased with an increase in the length of the methylene spacer.
__________
Translated from Journal of Qingdao University of Science and Technology, 2006, 27(1) (in Chinese) 相似文献
863.
The thermodynamic properties of saturated aqueous lanthanide nitrate solutions were determined using recently published critically evaluated solubility and activity data. The variation of the thermodynamic functions and congruent melting points as a function of atomic number are interpreted in terms of changes in inner sphere coordination number in both the solid hexahydrates and in the aquo ions, and in terms of the double-double effect.Inconsistencies in experimental solubility data are generally caused by uncertainties in solid phase composition which is shown to be due to the very small Gibbs energies accompanying transitions from stable to metastable systems differing in the number of hydrating water molecules.Presentation to First International Symposium on Solubility Phenomena, University of Western Ontario, London, Ontario, August 21–23, 1984. 相似文献
864.
Summary A method for the separation of substituted tetraphenylporphyrins by preparative liquid chromatography is reported. The quality of the columns formed by axial compression of various stationary phases is tested. 相似文献
865.
JiKuanZHAO XiaoCHEN ChunJieYANG ZhenMingSUI YongCunCHAI GuoDongZHANG JieLIU 《中国化学快报》2005,16(4):557-560
Silver and gold organosols are easily prepared by transferring nanoparticles from aqueous phase into isooctane with high efficiency (>90%). Concentrations of sodium oleate and magnesium chloride have crucial effects on the transfer efficiency. Based on the UV-visible absorption spectra, TEM micrographs of nanoparticles, as well as molecular modeling calculation about the adsorption conformation of sodium oleate molecules, a possible phase transfer mechanism is proposed. 相似文献
866.
Zhaofei Li Junliang Sun Chun-K. Loong Fuhui Liao 《Journal of solid state chemistry》2005,178(11):3315-3322
A powder sample of Sr3FeMoO7 was synthesized by solid-state reaction in reduced atmosphere (5% H2/Ar). At room temperature, Sr3FeMoO7 crystallizes in a typical Ruddlesden-Popper (n=2) structure in the space group I4/mmm, and . The structure refinement indicates that the Fe and Mo ions are randomly distributed in a single B-site with small fraction of B-site and oxygen vacancies. At low temperature, long-range magnetic interaction was observed. The antiferromagnetic magnetic interaction can be described with a large unit cell, and cm=cn, in the magnetic space group An′. 相似文献
867.
868.
Summary A new stationary phase [bikis(2,6-di-O-pentyl-3-O-hex-6-enyl)-pentakis(2,6-di-O-pentyl-3-O-methyl)-β-CD-polysiloxane] was
synthesized and successfully applied in GC for the separation of chiral and achiral isomers. It possesses high column efficiency
and exhibits excellent separation ability for disubstituted benzenes. Some typical enantiomers and optical isomers are well
separated. The separation behavior of this new phase is characterized and discussed. 相似文献
869.
Tsutomu Takeichi Hiroshi Yada Yuzi Takayama Masami Morikawa 《Journal of separation science》1995,18(10):630-634
A chiral stationary phase prepared by bonding L -valine-t-butylamide to XE-60 has been coated on glass and metal capillaries. The performances of the chiral glass and metal columns were equivalent to those of commercial fused silica capillary columns. The thermal stability of the glass column was examined up to 280°C. It was found that no appreciable change in separation factor (α value) was observed up to 230°C. The α values gradually decreased between 240 and 260°C, and enantiomer separation was no longer achieved at 280°C. It was concluded that the allowable upper limit temperature of the chiral stationary phase is between 230 and 240°C in the isothermal mode, and ca 260°C in temperature-programmed mode. 相似文献
870.
The multielement trace analytical method ‘total reflection X-ray fluorescence’ (TXRF) has become a successfully established method in the semiconductor industry, particularly, in the ultra trace element analysis of silicon wafer surfaces. TXRF applications can fulfill general industrial requirements on daily routine of monitoring wafer cleanliness up to 300 mm diameter under cleanroom conditions. Nowadays, TXRF and hyphenated TXRF methods such as ‘vapor phase decomposition (VPD)-TXRF’, i.e. TXRF with a preceding surface and acid digestion and preconcentration procedure, are automated routine techniques (‘wafer surface preparation system’, WSPS). A linear range from 108 to 1014 [atoms/cm2] for some elements is regularly controlled. Instrument uptime is higher than 90%. The method is not tedious and can automatically be operated for 24 h/7 days. Elements such as S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Br, Sn, Sb, Ba and Pb are included in the software for standard peak search. The detection limits of recovered elements are between 1×1011 and 1×107 [atoms/cm2] depending upon X-ray excitation energy and the element of interest. For the determination of low Z elements, i.e. Na, Al and Mg, TXRF has also been extended but its implementation for routine analysis needs further research. At present, VPD-TXRF determination of light elements is viable in a range of 109 [atoms/cm2]. Novel detectors such as silicon drift detectors (SDD) with an active area of 5 mm2, 10 mm2 or 20 mm2, respectively, and multi-array detectors forming up to 70 mm2 are commercially available. The first SDD with 100 mm2 (!) area and integrated backside FET is working under laboratory conditions. Applications of and comparison with ICP-MS, HR-ICP-MS and SR-TXRF, an extension of TXRF capabilities with an extremely powerful energy source, are also reported. 相似文献