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Structural and Chemical Characterization of Cerium Oxide Thin Layers Grown on Silicon Substrate
2015
In this study, we report transmission electron microscopy and electron energy loss spectroscopy study of cerium oxide thin layers deposited on silicon substrate. Transmission electron microscopy experiments have revealed the flat morphology of the deposited layers. In addition, studies of high resolution images have indicated the presence of mainly ceria crystallized nanoparticles. Energy electron loss spectroscopy measurements were also performed in scanning mode to study the evolution of the cerium valence. In addition to Ce4+ inside the layer, the presence of amorphous cerium silicate with valence +3 is pointed out at the vicinity of the substrate.
Mechanical performance of experimental acrylic resins modified by nanoparticles after chemical and mechanical degradation.
2020
Background Different materials have been incorporated into the polymethylmethacrylate matrix to improve its performance. The aim of this study was to evaluate the degree of conversion (DC), the flexural strength (FS), the elasticity modulus (EM), and the effect of exposure to food-simulating liquids prior to brushing simulation on the gloss loss (GL) of experimental acrylic resins modified by nanoparticles. Material and methods Three different types of nanoparticles; silicon oxide (SiO2), cerium oxide (CeO2) and titanium oxide (TiO2) were added to a poly (methylmethacrylate) matrix, in proportions of 0.5wt%, 1wt% and 3wt% each, forming nine experimental groups. The acrylic resin was also te…
Preparation of magnetron sputtered thin cerium oxide films with a large surface on silicon substrates using carbonaceous interlayers.
2013
The study focuses on preparation of thin cerium oxide films with a porous structure prepared by rf magnetron sputtering on a silicon wafer substrate using amorphous carbon (a-C) and nitrogenated amorphous carbon films (CNx) as an interlayer. We show that the structure and morphology of the deposited layers depend on the oxygen concentration in working gas used for cerium oxide deposition. Considerable erosion of the carbonaceous interlayer accompanied by the formation of highly porous carbon/cerium oxide bilayer systems is reported. Etching of the carbon interlayer with oxygen species occurring simultaneously with cerium oxide film growth is considered to be the driving force for this effec…
MOCVD growth of porous cerium oxide thin films on silicon substrate
2015
Abstract Porous cerium oxide thin films were grown by pulsed direct liquid injection metal organic chemical vapor deposition (DLI-MOCVD) on silicon substrate, using cerium tetrakis (1-methoxy-2-methyl-2-propanolate) dissolved in cyclohexane as precursor as well as oxygen as oxidant agent. The chemical and morphological characteristics of the films were investigated by XPS, SEM and TEM. The influence of the growth conditions on the morphological features of the thin films and the cerium chemical states are reported and discussed. The decrease of the oxygen and/or alkoxide flow rate induces the decrease of both the film thickness and the porosity of the layer. Moreover, the growth of silicate…
La cerámica valenciana del siglo XV como modelo en la Italia del Quattrocento
2003
En este artículo se analiza un hecho insólito en la historia del arte español: productos creados en el siglo XV en Manises y Paterna, poblaciones cercanas a la ciudad de Valencia, sirven de modelo a otros italianos coetáneos y no a la inversa. Se trata de cerámica arquitectónica, "azulejos" (tiles), así como de piezas de vajilla. Y ello tanto en lo referente a las formas como al repertorio ornamental. (A)
La tinaja de Caná
2005
Los curiosos avatares de un vaso de reflejo dorado que hoy en día se conserva en el Museo Nacional de Estocolmo nos permiten recordar las conexiones entre la alquimia y la cerámica a lo largo de la historia. (A)
Sobre una escena de "hombre-ciervo" en la Terra Sigillata Hispánica
2002
Los elementos figurados que aparecen sobre la superficie de los vasos de Terra Sigillata Hispánica, nos informan de costumbres, mitos, creencias, gustos del mundo hispano que les dieron forma. Su identificación iconográfica nos aportará datos para la comprensión del proceso romanizador, de la asimilación por las gentes peninsulares de los modelos romanos, así como de la pervivencia de tradiciones indígenas. Analizamos en el artículo una escena, hasta ahora relacionada con el mito de Acteón, y aportamos datos para su posible identificación.
Uniformization with infinitesimally metric measures
2019
We consider extensions of quasiconformal maps and the uniformization theorem to the setting of metric spaces $X$ homeomorphic to $\mathbb R^2$. Given a measure $\mu$ on such a space, we introduce $\mu$-quasiconformal maps $f:X \to \mathbb R^2$, whose definition involves deforming lengths of curves by $\mu$. We show that if $\mu$ is an infinitesimally metric measure, i.e., it satisfies an infinitesimal version of the metric doubling measure condition of David and Semmes, then such a $\mu$-quasiconformal map exists. We apply this result to give a characterization of the metric spaces admitting an infinitesimally quasisymmetric parametrization.
Infrared study of the MoO3 doping efficiency in 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP)
2013
AbstractElectrochemical doping produces clear changes in the vibrational spectra of organic semiconductors as we show here for the system molybdenum oxide (MoO3) doped into the charge transport material 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP). Based on density-functional theory (DFT) calculations of vibrational spectra, the new spectral features can be attributed to the CBP cation that forms as a result of electron transfer from CBP to MoO3. The intensity of the new vibrational lines is a direct measure for the probability of charge transfer. MoO3 agglomerating within the CBP matrix limits the active interface area between the two species. The appearance of a broad electronic transition …
Incomplete Charge Collection at Inter-Pixel Gap in Low- and High-Flux Cadmium Zinc Telluride Pixel Detectors.
2022
The success of cadmium zinc telluride (CZT) detectors in room-temperature spectroscopic X-ray imaging is now widely accepted. The most common CZT detectors are characterized by enhanced-charge transport properties of electrons, with mobility-lifetime products μeτe > 10−2 cm2/V and μhτh > 10−5 cm2/V. These materials, typically termed low-flux LF-CZT, are successfully used for thick electron-sensing detectors and in low-flux conditions. Recently, new CZT materials with hole mobility-lifetime product enhancements (μhτh > 10−4 cm2/V and μeτe > 10−3 cm2/V) have been fabricated for high-flux measurements (high-flux HF-CZT detectors).…