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Rare Earth Metal (rare + earth_metal)
Selected AbstractsChemInform Abstract: Nitrides with Inverse K2[NiF4] Structure: (R1-xCa3+xN1-x/3)Bi2 with R: Rare Earth Metal.CHEMINFORM, Issue 37 2010Frank Gaebler Abstract The new compounds (La1-xCa3+xN1-x/3)Bi2 (x= 0.10, 0.05, 0.00), (Ce0.7Ca3.3N0.9)Bi2, and (PrCa3N)Bi2 are characterized by powder X-ray and neutron diffraction, magnetic susceptibility, and electrical resistivity measurements. [source] Solid State and Electronic Structure of Rare Earth Metal Intercalated Graphite from First-Principles TheoryCHEMINFORM, Issue 37 2007Chang-Ming Fang Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Crystal Structures of KNdTe4, RbPrTe4, and RbNdTe4 , Investigations Concerning the Thermal Stability of KNdTe4 as well as Some Remarks Concerning Additional Representatives of the Composition ALnTe4 (A: K, Rb, Cs and Ln: Rare Earth Metal).CHEMINFORM, Issue 20 2003Klaus Stoewe Abstract For Abstract see ChemInform Abstract in Full Text. [source] Friedel,Crafts Reaction Catalyzed by Perfluorinated Rare Earth Metals.CHEMINFORM, Issue 1 2003Min Shi Abstract For Abstract see ChemInform Abstract in Full Text. [source] In situ ellipsometric studies of formation kinetics of rare earth metal conversion coatings on magnesium alloyPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2008Lingjie Li Abstract In situ spectroscopic ellipsometry was employed to investigate the initial regime of rare earth metal (REM) conversion coatings formation on AZ31 magnesium alloy. Three REM salts solutions, 0.05 mol·dm -3 Ce(NO3)3, La(NO)3 and Sm(NO)3 solutions, were used for REM conversion coatings preparation. By deconvoluting the ellipsometric data, the surface of the fresh well-polished AZ31 magnesium alloy was found to be covered with 15.80 nm thick native (hydr)oxide film; the refractive indices and the thickness of Ce, La and Sm conversion coatings were obtained. The formation kinetics of three REM coatings follows different exponential functions and the coatings exhibit different optical properties. La conversion coating has the largest n values and the lowest k values while Sm conversion coating is just opposite. Moreover, the pH variation of the bulk conversion solutions upon the coatings formation was recorded. It is confirmed that the reduction of protons leads to the interfacial pH increasing and further results in the precipitation of REM hydroxide gel, which is critical for the REM conversion coatings formation. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Rare Earth Benzotriazolates: Coordination Polymers Incorporating Decomposition Products from Ammonia to 1,2-Diaminobenzene in,1[Ln(Btz)3(BtzH)] (Ln = Ce, Pr), ,1[Ln(Btz)3{Ph(NH2)2}] (Ln = Nd, Tb, Yb), and ,1[Ho2(Btz)6(BtzH)(NH3)],EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 10 2006Klaus Müller-Buschbaum Abstract The solvent-free melt reactions of benzotriazole (BtzH, C6H4N2NH) with rare earth metals result in three different types of benzotriazolate coordination polymers. Early 4f metals yield ,1[Ln(Btz)3(BtzH)] [Ln = Ce (1), Pr (2)], from neodymium to ytterbium the type ,1[Ln(Btz)3{Ph(NH2)2}] is observed [Ln = Nd (3), Tb (4), Yb (5)], whereas the late 4f metal Ho gives ,1[Ho2(Btz)6(BtzH)(NH3)] (6). Depending on the reaction conditions and the respective rare earth element, ligand fragments originating from decomposition products are incorporated in the coordination polymers. Compounds 1,3 and 6 were obtained as single crystals and their crystal structures determined by single-crystal X-ray analysis, whilst 4 and 5 were obtained as powders. X-ray powder diffraction shows the isotypic character of polymers 3, 4, and 5. The benzotriazolates contain trivalent lanthanide ions with complete nitrogen coordination. Decomposition of the ligand accompanies the formation of the coordination polymers. X-ray analysis was combined with thermal analysis and mass spectrometry to investigate the influence of reaction temperatures on ligand decomposition. Ln-benzotriazolates exhibit aspects of materials science such as luminescence {5D4,7FJ, J = 4,6 for ,1[Tb(Btz)3{Ph(NH2)2}] (4)} without quenching by concentration. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Comparison of the surface and catalytic properties of rare earth-promoted CaO catalysts in the oxidative coupling of methaneJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2006Vilas H Rane Abstract Rare earth (viz. La, Ce, Sm, Nd and Yb) promoted CaO catalysts have been investigated, comparing their surface properties (viz. surface area and basicity/base strength distribution) and catalytic activity/selectivity in the oxidative coupling of methane at different reaction conditions (temperatures, 650,800 °C, CH4/O2 ratios, 2.0,8.0 and space velocity, 51 360 cm3 g,1 h,1). The surface properties and catalytic activity/selectivity are strongly influenced by the rare earth promoter and its concentration. Apart from the Sm-promoted CaO catalyst, both the total and strong basic sites (measured in terms of CO2 chemisorbed at 50° and 500 °C respectively) are decreased due to the promotion of CaO by rare earth metals (viz. La, Ce, Nd and Yb). The catalytic activity/selectivity is strongly influenced by the temperature, particularly below ,700 °C, whereas at higher temperature no further effect is seen. The La2O3CaO, Nd2O3CaO and Yb2O3CaO catalysts showed high activity and selectivity, and also their results are comparable. Among the catalysts, Nd-promoted CaO (with Nd/Ca = 0.05) showed the best performance (19.5% CH4 conversion with 70.8% C2+ selectivity) in the oxidative coupling of methane. A close relationship between the surface density of total and strong basic sites (measured in terms of CO2 chemisorbed at 50° and 500 °C respectively) and the C2+ selectivity and/or C2+ yield has been observed. Copyright © 2005 Society of Chemical Industry [source] | ||||||||||