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Metallic Phase (metallic + phase)
Selected AbstractsElectron Structure of the K3Bi2 Metallic PhaseCHEMINFORM, Issue 22 2005Pere Alemany Abstract For Abstract see ChemInform Abstract in Full Text. [source] Electronic Structures of KNa3In9 and Na2In, Two Metallic Phases with Classical Closed-Shell Electronic Configurations.CHEMINFORM, Issue 24 2006Bin Li 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] Redox Active Two-Component Films of Palladium and Covalently Linked Zinc Porphyrin,Fullerene DyadELECTROANALYSIS, Issue 9 2006Marta Plonska Abstract Redox active films have been generated electrochemically by the reduction of dyads consisting of fullerene C60 covalently linked to zinc meso -tetraphenyloporphyrin, ZnPC60, and palladium acetate. The films are believed to consist of a polymeric network formed via covalent bonds between the palladium atoms and the fullerene moieties. In these films, the zinc porphyrin moiety is covalently linked to the polymeric chains through the pyrrolidine ring of the fullerene. The ZnPC60/Pt films are electrochemically active in both positive and negative potential excursions. At positive potentials, two oxidation steps for the zinc porphyrin are observed. In the negative potential range, electron transfer processes involving the zinc porphyrin and the fullerene entities are observed. Film formation is also accompanied by palladium deposition on the electrode surface. The presence of a metallic phase in the film influences its morphology, structure and electrochemical properties. [source] 55Mn NMR study in magnetically ordered state of perovskite manganitesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2004K. Shimizu Abstract We present NMR results of Pr1,xSrxMnO3 and their lacunar samples, and also present results of the single crystalline layered manganites La1.2Sr1.8Mn2O7 and La1.2Sr1.6Ca0.2Mn2O7. In Pr1,xSrxMnO3, a single resonance line is observed for 0.27 , x , 0.4, which indicates the sample to be in a metallic state. In the Pr and Sr deficient samples, the NMR line arising from Mn2+ is observed. Introducing deficiency to Pr or Sr sites, a charge disproportionation of the type 2Mn3+, Mn2+ + Mn4+ probably occurs. For La1.2Sr1.8Mn2O7 and La1.2Sr1.6Ca0.2Mn2O7 compounds, the NMR spectra under an external field of 1.5 T are broad and spread with several distinct lines in the frequency range 310,420 MHz. This is different from the results of La1,xSrxMnO3 and Pr1,xSrxMnO3 with a metallic state, where a single line has been observed. The distinct NMR lines are ascribed to Mn4+, Mn3+ and metallic phase, taking account of the results for La1,xSrxMnO3 and Pr1,xSrxMnO3. In addition to the NMR line from the metallic phase, the observation of Mn3+ and Mn4+ lines suggests a phase separation at low temperature in La1.2Sr1.8Mn2O7 and La1.2Sr1.6Ca0.2Mn2O7. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Double exchange model in cubic vanadatesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 1 2006Krzysztof Wohlfeld Abstract We investigate the role of the double exchange mechanism for stability of the metallic C-type antiferromagnetic (C-AF) phase, which was observed experimentally in hole doped La1,xSrx VO3. The double exchange model treats localized electrons in xy orbitals as classical S = 1/2 spins, which interact by Hund's exchange JH with yz /zx electrons in partly filled t2g orbitals. Including strong on-site Coulomb repulsion U between t2g electrons, and using slave boson method we demonstrate that C -AF and metallic phase can be stabilized due to the specific features of the hopping in degenerate and partly filled t2g orbitals. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Studies on structural and optical properties of Cu-Sb-O thin filmsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2010Nadia Chaglabou Abstract We report in this paper the structural and optical properties of Cu-Sb-O thin films systems. Samples were prepared via sequential thermal vacuum deposition of Cu and Sb or Sb and Cu (10 -5 Torr) on glass substrates after what they were heated in vacuum at 200 °C for 1 hour. So, the obtained intermetallic multilayer systems (Cu/Sb)j=1,2,3 and (Sb/Cu)j=1,2,3 were annealed in air atmosphere between 30°C and 400 °C for 3 h for j=1; for 6 h for j=2 and for 9 h for j=3. These films were characterized for their structural, surface morphological, compositional, and optical properties by using X-ray diffraction (XRD) and optical (transmittance and reflectance) measurement techniques. The X-ray diffraction (XRD) patterns revealed the presence of CuO, Sb2O3 and Sb2O4phases. The absorption coefficient of Cu-Sb-O thin films in all cases is in the range104 -105 cm -1. The films after annealing have two direct band gap energies in the ranges 1.48,1.50 eV and 2.20-2.95 eV. The electrical measurements show a conversion from a metallic phase to the semiconductor phase after annealing. The samples exhibit p-type conductivity after annealing in air of the intermetallic multilayer systems (Cu/Sb)j=3 and (Sb/Cu)j=3. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Oxidation-induced high-Curie-temperature ferromagnetism in CoAl(100)PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2007V. Rose Abstract In conventional magnetic materials, oxidation is a disagreeable effect that often lowers or destroys the magnetic capabilities of those materials. By contrast, we report on the decisive paramagnetic-ferromagnetic phase transition in CoAl(100) at room temperature, utilizing oxidation of stoichiometric CoAl. We also discuss the control and drastic increase of the coercive field by subsequent annealing of the oxidized sample. The alumina film grown by selective oxidation protects the alloy from oxidation of Co, despite the accumulation of Al vacancies and the resulting enrichment in Co of the metallic phase underneath the oxide film. As a result, a ferromagnetic thin Co-rich phase is formed at the interface between the insulating aluminum oxide and the paramagnetic Co50Al50 bulk. The creation via simple oxidation of a ferromagnetic thin film underneath a surface insulator demonstrates a novel path to building the majority of a magnetic tunnel junction. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Electrical transport in strained La0.7Ca0.3MnO3 filmsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2006V. Markovich Abstract Magnetotransport properties of La0.7Ca0.3MnO3 thin films deposited on (100) LaAlO3 substrate were investigated. Fine balance between the charge ordered insulating phase and ferromagnetic metallic phase results in a number of glassy features such as: significant hysteresis, memory effects and long-time resistivity relaxation at turning on and off of magnetic field. It was found that in the temperature range 10,220 K the resistance of thin film decreases significantly upon applying electric current and this effect cannot be explained by homogeneous Joule heating. The magnetotransport properties of the thin films are discussed in the frame of cross-coupling of charge, spin and strain. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Study on surface morphology and selectivity of precipitated iron catalysts of FTSASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009Wang Xingjun Abstract The precipitated iron catalyst was prepared by co-precipitation. The surface morphology of the catalyst was investigated under different reduction conditions by SEM (S-250, USA). Under H2 -reduction, the surface morphology of the catalyst had the obvious changes, which the diameter reduced, adhered together, came into being wads considered as a group. But the surface morphology of the catalyst had almost no change under CO reduction. The crystal structure of the catalyst was studied under different reduction conditions by X-ray diffraction (XRD) (Rigaku D/max, Japanese). It was found that the catalyst was reduced completely with H2, but it was reduced partly with CO. The crystal structure of the catalyst converted into the metallic phase with H2 reduction. However, most of the iron converted into iron oxide (Fe3O4) with CO reduction. And the predominant phase in a sample of a mature catalyst is ,-Fe5C2, which is the active phase in the Fischer-Tropsch synthesis (FTS). The experimental results showed that CO conversion and H2 conversion increase with the change of reaction temperature from 260 to 300 °C, under the conditions of pressure P = 2.6 MPa, space velocity = 0.86 Nl h,1 g-Fe,1, n(H2)/n(CO) = 2/3, and most of the hydrocarbon products are C5,11 which hold half of the hydrocarbon products. The next content is C2,4 which holds the quarter of hydrocarbon products. Then it is C12+, which is equal to 18%. And the last is C1, which is equal to 7%. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | |||||||||||||