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Stoichiometric Mixture (stoichiometric + mixture)
Selected AbstractsGrowth, structure and thermal properties of CuAlxGa1-xSe2 alloysCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2006J. Castro Abstract Ingots of the CuAlxGa1-xSe2 (0 , x , 1) alloys system were prepared by direct fusion of the stoichiometric mixture of the elements. The analysis of X-ray Powder Diffraction data showed the presence of one single phase with chalcopyrite tetragonal structure at room temperature for all the studied compositions. The lattice parameters, a and c, and the bond lengths were calculated. The phase transition temperatures were obtained by the onset method from Differential Thermal Analysis measurements performed on samples sealed in evacuated quartz ampoules. Fusion or transition enthalpies were determined from the area of the corresponding DTA peak. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The reactive Riemann problem for thermally perfect gases at all combustion regimesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 3 2010A. Beccantini Abstract In this work we analyze the reactive Riemann problem for thermally perfect gases in the deflagration or detonation regimes. We restrict our attention to the case of one irreversible infinitely fast chemical reaction; we also suppose that, in the initial condition, one state (for instance the left one) is burnt and the other one is unburnt. The indeterminacy of the deflagration regime is removed by imposing a (constant) value for the fundamental flame speed of the reactive shock. An iterative algorithm is proposed for the solution of the reactive Riemann problem. Then the reactive Riemann problem and the proposed algorithm are investigated from a numerical point of view in the case in which the unburnt state consists of a stoichiometric mixture of hydrogen and air at almost atmospheric condition. In particular, we revisit the problem of 1D plane-symmetric steady flames in a semi-infinite domain and we verify that the transition from one combustion regime to another occurs continuously with respect to the fundamental flame speed and the so-called piston velocity. Finally, we use the ,all shock' solution of the reactive Riemann problem to design an approximate (,all shock') Riemann solver. 1D and 2D flows at different combustion regimes are computed, which shows that the approximate Riemann solver, and thus the algorithm we use for the solution of the reactive Riemann problem, is robust in both the deflagration and detonation regimes. Copyright © 2009 John Wiley & Sons, Ltd. [source] Synthesis of Phase-Pure Pb(ZnxMg1,x)1/3Nb2/3O3 up to x= 0.7 from a Single Mixture via a Soft-Mechanochemical RouteJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2000Seiji Shinohara Phase-pure perovskite Pb(ZnxMg1,x)1/3Nb2/3O3 solid solution (PZxM1,xN) is obtained for x, 0.7 by heating a milled stoichiometric mixture of PbO, Mg(OH)2, Nb2O5, and 2ZnCO3·3Zn(OH)2·H2O at 1100°C for 1 h. Percent perovskite (fP) with respect to total crystalline phase decreases with increasing temperature of subsequent heating then increases to 900°C for the mixtures where x, 0.8 and milled for 3 h. For mixtures with x= 0.9 and x= 1, fP decreases monotonically. Curie temperature increases almost linearly with increasing x up to x= 0.7. The maximum dielectric constant at 1 kHz is 2×104 and 1.7×104 for the mixture with x= 0.4 and x= 0.7, respectively. The stabilization mechanism of strained perovskite is discussed. [source] Structures of incommensurate and commensurate composite crystals RbxMnO2 (x = 1.3711, 1.3636)ACTA CRYSTALLOGRAPHICA SECTION B, Issue 1 2010Jürgen Nuss Rb1.3711MnO2 (Rb11Mn8O16) has been synthesized via the azide/nitrate route from a stoichiometric mixture of the precursors Mn2O3, RbNO3 and RbN3. The structure of this extremely air- and moisture-sensitive compound can best be described in terms of an incommensurate composite structure, built up by a honeycomb-like framework of Rb ions, as one subsystem and by a second subsystem of chains, consisting of edge-sharing MnO4/2 tetrahedra. These two composite substructures interpenetrate in such a way that the manganate chain polyanions centre the channels of the Rb-honeycomb framework. Crystals transform by an aging process into Rb1.3636MnO2 (Rb15Mn11O22), which has a similar structure but a different commensurate modulation. Two reasons can be established for the origin of the modulations: the charge ordering of Mn2+/Mn3+ on one hand, and the incompatibility of the Mn,Mn and Rb,Rb separations on the other. [source] Influence of dT20 and [d(AT)10]2 on Cisplatin Hydrolysis Studied by Two-Dimensional [1H,15N] HMQC NMR SpectroscopyCHEMISTRY - A EUROPEAN JOURNAL, Issue 13 2005Jo Vinje Dr. Abstract The influence of the presence of DNA on the kinetics of cisplatin (cis -[PtCl2(NH3)2]) aquation (replacement of Cl, by H2O) and anation (replacement of H2O by Cl,) involved in the hydrolysis of cisplatin have been determined by two-dimensional [1H,15N] HMQC NMR spectroscopy. Single-stranded dT20 and double-stranded [d(AT)10]2 oligonucleotides were used as DNA models, avoiding guanines which are known to react rapidly with aquated cisplatin forms. Reactions starting from cis -[PtCl2(15NH3)2], or from a stoichiometric mixture of cis -[Pt(15NH3)2(H2O)2]2+ and Cl, (all 0.5,mM PtII; in ionic strength, adjusted to 0.095,M or 0.011,M with NaClO4, pH between 3.0 and 4.0) were followed in an NMR tube in both the absence and presence of 0.7,mM dT20 or [d(AT)10]2. In the presence of dT20, we observed a slight and ionic-strength-independent decrease (15,20,%) of the first aquation rate constant, and a more significant decrease of the second anation rate constant. The latter was more important at low ionic strength, and can be explained by efficient condensation of cis -[Pt(15NH3)2(H2O)2]2+ on the surface of single-stranded DNA, in a region depleted of chloride anions. At low ionic strength, we observed an additional set of [1H,15N] HMQC spectral signals indicative of an asymmetric species of PtN2O2 coordination, and we assigned them to phosphate-bound monoadducts of cis -[Pt(15NH3)2(H2O)2]2+. Double-stranded [d(AT)10]2 slowed down the first aquation step also by approximately 15,%; however, we could not determine the influence on the second hydrolysis step because of a significant background reaction with cis -[Pt(NH3)2(H2O)2]2+. [source] Synthesis and Structure of [nPr3N(CH2)6NnPr3][CuFe3Br3(SePh)6], [Cu5Fe(SePh)7(PPh3)4] and [Cu4Fe3(SePh)10(PPh3)4],EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2007Andreas Eichhöfer Abstract CuBr and Fe(OOCCH3)2 react with PhSeSiMe3 in acetonitrile in the presence of the diammonium salt [nPr3N(CH2)6NnPr3]Br2 to yield ionic [nPr3N(CH2)6NnPr3][CuFe3Br3(SePh)6]. The neutral complexes [Cu5Fe(SePh)7(PPh3)4] and [Cu4Fe3(SePh)10(PPh3)4] were obtained by similar reactions of different stoichiometric mixtures of CuOOCCH3 and FeCl2 with PPh3 and PhSeSiMe3. The crystal structures of the compounds were determined by single-crystal X-ray analysis to give new structural types of molecular cluster compounds formed by copper, iron and selenium. Thermal treatment of [Cu5Fe(SePh)7(PPh3)4] and [Cu4Fe3(SePh)10(PPh3)4] resultsin the formation of mixtures of binary Cu2Se and ternaryCuFeSe2.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] ChemInform Abstract: Synthesis and Structural Chemistry of La18Li8Rh4MO39 (M = Ti, Mn, Ru).CHEMINFORM, Issue 42 2010Peter D. Battle Abstract The title compounds are synthesized by solid state reactions of stoichiometric mixtures of La2O3, Rh2O3, MO2 (M: Ti, Mn, Ru), and a 50% excess of Li2CO3 (800 °C, 12 h). [source] ChemInform Abstract: Structural Chemistry and Magnetic Properties of Ln18Li8Rh5-xFexO39 (Ln: La, Nd).CHEMINFORM, Issue 36 2010Peter D. Battle Abstract The title compounds (0.5 , x , 5) are synthesized by solid state reactions of stoichiometric mixtures of the metal(III) oxides and a 50% excess of Li2CO3 (air, 800 °C, 12 h; 1000 °C, 1 h). [source] ChemInform Abstract: Synthesis, Characterization, and Crystallographic Study of the PbO,Bi2O3,V2O5 System: Pb3-xBi2x/3V2O8 (0.20 , x , 0.50).CHEMINFORM, Issue 35 2010Prangya Parimita Sahoo Abstract The new title solid solution is synthesized by solid state reaction of stoichiometric mixtures of PbO, Bi2O3, and V2O5 (650 °C, 2 d). [source] ChemInform Abstract: Li3V(MoO4)3: A New Material for Both Li Extraction and Insertion.CHEMINFORM, Issue 33 2010D. Mikhailova Abstract The title compound is prepared from stoichiometric mixtures of Li2MoO4, MoO3, and V2O3 (Ar, silica tube, 813 K, 30 h) and characterized by single crystal XRD, electrochemical measurements, XPS, and magnetic measurements. [source] | ||||||||||