Procedimiento de obtención de cintas, hilos o láminas superconductoras de Hg(1-x) Mx Ba(2-y) Sry Ca(n-1) Cun O(2n+2+δ) con substratos de base Ag

Referencia OEPM: P200001699.-- Fecha de solicitud: 07/07/2000.-- Titular: Consejo Superior de Investigaciones Científicas (CSIC).Procedimiento de obtención de cintas, hilos o láminas superconductoras de Hg(1-x) Mx Ba(2-y) Sry Ca(n-1) Cun O(2n+2+δ) utilizando la Ag y sus aleaciones como soporte o substrato metálico, con las siguientes etapas: a) preparación de una mezcla homogénea del óxido mixto superconductor o de los óxidos precursores multifásicos correspondientes con un exceso de Hg, HgO, CaHgO2 u otra fuente de mercurio cuyo objetivo sea saturar la Ag en forma de amalgama; b) las reacciones simultáneas vapor-sólido producidas entre 700°C y 900°C para dar lugar a la formación, recristalización y conexión de los granos superconductores mientras que la reacción de amalgamación con la Ag transcurre paralelamente con el exceso de Hg (vapor); c) repetición del proceso b previa nueva deformación plástica de la lámina, cinta o hilos por prensado, laminado o trefilado para mejorar la textura del superconductor.Peer reviewe

A simple statistical phenomenological model for cation substitutions in Nd1+xBa2-xCu3O7-d+x/2

International audienceIn this article we present the first results of a quite simple phenomenological model we have developed to simulate the cationic substitutions in Nd1+xBa2-xCu3O7+x/2-d (Nd123). Although elementary concepts from Statistical Mechanics had been used in it, significant results have been obtained, as the reconstruction of the substitution region limits and their dependence on temperature. Particularly interesting is the prediction of strong temperature dependence for the minimum of the substitution parameter x

Modeling of Atomic Migration Phenomena in Phase Change Memory Devices

Atomic migration on Phase Change Memory devices with wall architecture has been experimentally investigated and a quantitative model including electrical, thermal, and mechanical driving forces has been developed. The experimental results collected by driving the device with programming pulses with direct and reverse polarity have been accounted for. Comparison with data of atomic migration on heavily cycled cells is also provided

Fabrication of ordered Sb–Te and In–Ge–Te nanostructures by selective MOCVD

The controlled growth of chalcogenide nanoscaled phase change material structures can be important to facilitate integration and to enable complex architectures for phase change memory and other microelectronic applications. Here, the growth of Sb–Te and In–Ge–Te alloys by metal–organic chemical vapour deposition (MOCVD) on patterned substrates featured with an array of recesses (~130 nm features width) was investigated. High selectivity, with preferential growth on a CoSi2 metallic layer at the recess bottom with respect to the surrounding SiO2 masking layer, was obtained, leading to a single-step fabrication of arrays of high-aspect-ratio chalcogenide nanostructures. The growth selectivity, as well as the morphology, composition and microstructure of the grown nanostructures, as a function of the different MOCVD process parameters, were investigated by scanning electron microscopy, transmission electron microscopy, energy dispersive x-ray spectroscopy, Raman spectroscopy and Fourier transformed infrared spectroscopy. Thanks to the chosen substrates, the synthesized nanostructures were also directly electrically accessible, as proved by conductive-atomic force microscopy

Temperature-dependent thermal characterization of Ge 2 Sb 2 Te 5 and related interfaces by the photothermal radiometry technique

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Hot-wire chemical vapor deposition of chalcogenide materials for phase change memory applications

The successful growth of chalcogenide films with required functional properties for PCM (phase change memory) by the combination of hot-wire MOCVD and pulsed liquid injection, was reported. Ge(NMe2)4, Sb(NMe2)3, and Te(i-Pr)2 precursors were used for GST depositions. additional optimization of deposition conditions was made in order to decrease the crystallites size and surface roughness of GST films. Smaller crystallites and smoother films were obtained at higher distance between the hot wire and substrate and by adjusting the structure of precursor injection cycle, the pressure, and gas flow rate. The CVD GST emerged as an appealing technology that can enable he development of high aspect-ratio PCM cells with improved programming characteristics. © 2008 American Chemical SocietyPeer Reviewe