Search results for "Tin Dioxide"
showing 7 items of 7 documents
Hydrothermal growth mechanism of SnO2 nanorods in aqueous HCl
2018
Abstract Rutile-type nanorods of SnO2 were obtained in a one-pot hydrothermal synthesis starting from SnCl4·5H2O and HCl in a temperature range between 200 and 240°C. Although the nanorods are polydisperse, the average length of the nanorods could be adjusted from 13 to 65 nm by varying of the reaction temperature. The resulting anisotropic nanocrystals were characterized using powder X-ray diffraction (PXRD), (high resolution-) transmission electron microscopy (HR-TEM), and selected area electron diffraction (SAED). The particle growth proceeds via a dissolution-recrystallization process with soluble [SnCl5(H2O)]− intermediates, as confirmed by PXRD, Raman spectroscopy, and magic angle spi…
Densification of MnDoped Tin Oxide Films by Conventional Heating and Microwave Heating Treatment
2005
Mn(II) doped SnO2 thin films used for shielding fluoride glasses against corrosion were investigated by x-ray absorption spectroscopy (EXAFS and XANE)S at the Sn and Mn K-edges. The effect of firing treatment on the densification of the films was studied. It has been evidenced a partial change of Mn valence from 2.3 to 2.6 upon heating which is attributed to a change of ratios of two Mn sites: grafted divalent Mn ions at the surface of SnO2 nanocrystallites and trivalent Mn ions embedded into a substitutional solid solution with Sn.
Enzymatic Synthesis and Surface Deposition of Tin Dioxide using Silicatein-α
2011
Nanostructured tin dioxide was synthesized by making use of the catalytic activity of silicatein-α. TEM, HRTEM, and XRD revealed the formation of cassiterite SnO2. Surface bound silicatein retains its biocatalytic activity. This was demonstrated by immobilizing silicatein on glass surfaces using a histidine-tag chelating anchor. The subsequent deposition of SnO2 on glass was monitored by quartz crystal microbalance (QCM) measurements and scanning electron microscopy (SEM). This new aspect of silicatein activity toward the formation of metal oxides other than SiO2, TiO2, and BaTiO3 opens up new vistas in composite material synthesis.
Compressibility and structural behavior of pure and Fe-doped SnO2 nanocrystals
2017
We have performed high-pressure synchrotron X-ray diffraction experiments on nanoparticles of pure tin dioxide (particle size ~30nm) and 10 mol % Fe-doped tin dioxide (particle size ~18nm). The structural behavior of undoped tin dioxide nanoparticles has been studied up to 32 GPa, while the Fe-doped tin dioxide nanoparticles have been studied only up to 19 GPa. We have found that both samples present at ~13 GPa a second-order structural phase transition from the ambient pressure tetragonal rutile-type structure (P42/mnm) to an orthorhombic CaCl2-type structure (space group Pnnm). No phase coexistence was observed for this transition. Additionally, pure SnO2 presents a phase transition to a …
Characterization of V-doped SnO2 nanoparticles at ambient and high pressures
2018
Nanoparticles of V-doped SnO2 with stoichiometry Sn1-xO2Vx (x = 0.05, 0.075, 0.125) have been synthesized by a co-precipitation method. Their structural, vibrational, and nuclear properties have been characterized by x-ray Diffraction, Transmission Electron Microscopy, Energy Dispersive x-ray Spectroscopy, Raman Spectroscopy, and Mössbauer Spectroscopy (with 119Sn probe) at ambient pressure. We also performed high-pressure synchrotron x-ray diffraction experiments. The structural behaviour was studied up to ∼10 GPa under quasi-hydrostatic conditions. It has been found that tin dioxide nanoparticles with V are more compressible than un-doped tin dioxide nanoparticles. Fil: Ferrari, S. Consej…
A logarithmic multi-parameter model using gas sensor main and cross sensitivities to estimate gas concentrations in a gas mixture for SnO2 gas sensors
2007
Abstract In a metal-oxide semiconductor gas sensor, the sensitivity of the metal-oxide resistance to concentrations of reducing gases in the surrounding atmosphere is known to be related to adsorption and desorption of gas on the redox reactions between the gas and oxygen. Changes in the electric conductance due to these reactions were measured for tin dioxide semiconductor gas sensors. In this study, we propose a model of gas sensor responding behaviour using a relationship between sensor conductance and gas concentrations in a mixture. A least-squares method fit of measured data was applied to determining the values of coefficients. The proposed method uses main and cross sensitivities th…
Quantum Mechanical Co-Adsorption Modelling of Real Electrically Controlled Semiconductor Gas Sensors
2009
Abstract Co-adsorption of several gases is still a challenge due to the variety of reaction paths at the sensitive surface, and their competition for the adsorption sites. With an extended Wolkenstein model and the gas kinetic theory, we find that for specific paths their sequence of exposition has an important influence on the layer resistance as well as on the time required to achieve equilibrium. Whilst only processes that involve charge transfer can be electrically detected, a good correlation between model and electrical measurements needs weakly chemisorbed (physisorbed) layers to be taken in account. Our study presents a SnO2 nano-film sensor with electrical control electrodes expose…