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Synthesis of Aluminum-doped Zinc Oxide Nanowires Hydrotherma.ly Grown on Plastic Substrate

Advances in ma.erials Physics and Chemistry 2012年第4期2卷 56-59页

作者： Concepción Mejía García Elvia Díaz Valdés ana ma. paniagua mercado Arturo F. Méndez Sánchez José A. Andraca Adame Veluma.i Subrama.iam Josué Romero Ibarra Centro de Nanociencias y Micro y Nanotecnologías del IPN UPALM Luis Enrique Erro S/N México 07738 México Departamento de Física Escuela Superior de Física y Matemáticas – IPN Edif. 9 UPALM Col. San Pedro Zacatenco Deleg. GAM México 07738 México Depto. de Ing. Eléctrica Sección de Estado Sólido Av. IPN No. 2508 Col. San Pedro Zacatenco México 07360 México

We report the synthesis of undoped ZnO and Al-doped ZnO (ZnO:Al) nanowires grown using a two-step process: (a) preparation of the seed layer, and (b) growth of the nanostructures. In the first step,? 10 mM solutions of zinc acetate dihydrate and 1-propanol were spin coated on polyethylene terephthalate? (PET) substrate at 2000 rpm by 30 s. Vertical nanowires were then grown by dipping the substrates in an equimolar solution of zinc nitrate hexahydrate and hexamethylenetetramine. As doping source, aluminum nitrate nonahydrate powders were added in the solution. In the solutions, Al doping concentrations were established as 0.5 At %, 1.0 At %, 2.0 At % and 3.0 At %, respectively. The hydrotherma. process were carried out with a commercially microwave at 140 W power setting. The nanowires were characterized optically and morphologically. XRD patterns show the presence of ZnO, Zn(OH)2 and Zn6Al2O9. Scanning electron microscopy analysis showed that the size of ZnO nanowires was 50 nm in diameter. The undoped ZnO and ZnO:Al nanowires bandgap energy was obtained from optical transmission spectra.

关键词： Nanowires ZnO ZnO:Al Nanowires Spin Coating Hydrotherma. Process

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BPSCCO Superconducting Films Grown by Spray Pyrolysis Technique: Systema.ic Study of the Relationship between Pb Content and Annealing Conditions

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Advances in ma.erials Physics and Chemistry 2012年第4期2卷 92-95页

作者： Y Elvia Díaz Valdés Concepción Mejía García ana ma.ía paniagua mercado Arturo Méndez Sánchez Departamento de Física Escuela Superior de Física y Matemáticas – IPN Edif. 9 UPALM Col. San Pedro Zacatenco Deleg. GAM México 07737 México

Actually recent investigation in developing semiconducting-superconducting composites based in CdS and Bi-based superconductors has attracted interest in processing thin superconducting films. In this work are reported Bi-Pb-Sr-Ca-Cu-O (BPSCCO) thin films grown on MgO substrates by spray pyrolysis technique from a solution containing Bi(NO3)3, Pb(NO3)2, Sr(NO3)2, Ca(NO3)2 and Cu(NO3)2, with a subsequent solid state reaction for growing the Bi-based superconducting phases. Annealed films were characterized by X-ray diffraction, atomic absorption spectroscopy and resistance measurements. Interdependence between Pb content, annealing time and temperature, in the forma.ion of superconducting phases was studied applying a fractional factorial design 3III4-2. Interrelation between Pb content, ta and Ta exists. The presence of Pb is necessary to stabilize the high-Tc phase but its content depends on the annealing conditions.

关键词： Superconductivity BPSCCO Superconducting Films Spray Pyrolysis Deposition Pb Content Annealing Conditions Experimental Design

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Development And Characterization of Ultra Low Cement Castable Cordierites by Thixotropic Properties Mixtures

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Advances in ma.erials Physics and Chemistry 2012年第4期2卷 96-98页

作者： ana M. paniagua-mercado Arturo Méndez-Sánchez Elvia Díaz Valdés Concepción Mejía García Depto. de Física Escuela Superior de Física y Matemáticas Instituto Politécnico Nacional Col. Lindavista CP 03778 México D. F. México

The ma.n target in this investigation was to take advantage of the reology properties of the tixotropic mixes in Ultra Low Cement Castables (ULCC). The cordierite phase in refractory mix can be obtained using raw ma.erials with ma.nesium oxide in its composition, such as, Mg(OH)2 or H2Mg3(SiO3)4 (Talc mineral), with a content of? 63.5% SiO2, 31.7% MgO and 4.8% H2O. In this investigation, as ma.nesium source, a commercial calcined ma.nesite with 90% MgO was used.? This mineral was selected instead of Talc mineral, because this last contains more impurities in its composition that tend to form more amounts of liquid phases with low fusion points. For this work two different ULCC mixes were designed. These were fired at 1260 oC, the cordierite phase was quantified in each mix.

关键词： Reology Thixotropic Mixtures Ultra Low Cement Castables Cordierite

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Influence of Humidity on Yield Stress Determination by Slump Test of Slip-Prone Clayey Soils and Their Relation with the Chemical Properties

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Advances in ma.erials Physics and Chemistry 2012年第4期2卷 102-105页

作者： Arturo F. Méndez-Sánchez ana M. paniagua-mercado Karen E. Nieto-Zepeda Leonor Pérez-Trejo Elvia Diaz Valdés Concepción Mejía García Escuela Superior de Física y ma.emáticas Instituto Politécnico Nacional Edif. 9 Unidad Profesional Adolfo López Mateos Col. Lindavista C. P. 07738 México D. F. México.

In this work, the yield stress evaluation as a function of water content for slip-prone clayey soils is studied in order to understand how yield stress decreases as water content increases, and their relation with the chemical properties. The clayey soil samples were taken from the region of Teziutlán-Puebla-Mexico. Yield stress was calculated using the slump test in cylindrical geometry. Results show three zones. The first one shows an exponential decrement on yield stress due to lower water content in accord with clayey soils with high content of illita, followed by a second region where yield stress decreases drama.ically at a certain critical water concentration, and the third one where yield stress dependence is not well-defined since the clayey soil flow is seen. Finally, it is discussed how yield stress variation due to the water increment influences the landslide risk increment.

关键词： Clayey Soil Yield Stress Slump Test Microstructure Illita

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