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ABSTRACTPlasma sprayed pure alumina samples have been studied by Transmission Electron Microscopy and X–Ray diffraction. The main families of metastable forms (γ δ and θ) have been observed in as-sprayed or in annealed states. All derive... more
ABSTRACTPlasma sprayed pure alumina samples have been studied by Transmission Electron Microscopy and X–Ray diffraction. The main families of metastable forms (γ δ and θ) have been observed in as-sprayed or in annealed states. All derive from a spinel structure through a periodic antiphase boundaries mechanism, together with an ordering of vacant sites in the cationic sublattice.
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The epitaxial development of undoped zirconia films produced via the solution precursor route and deposited by dip-coating on (1120) planes of sapphire is investigated. After drying and firing at 600°C, polycrystalline films are made of... more
The epitaxial development of undoped zirconia films produced via the solution precursor route and deposited by dip-coating on (1120) planes of sapphire is investigated. After drying and firing at 600°C, polycrystalline films are made of nanosized randomly oriented tetragonal ZrO2 grains. Firing at higher temperatures promotes grain growth and islanding, so producing a layer of heteroepitaxial but isolated grains. Two
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Zirconia cordierite composite powders were fabricated by a sol-gel coating route. The crystallization of a deposited zirconia percursor thin layer and further phase transformation of tetragonal grains were shown to exhibit rather... more
Zirconia cordierite composite powders were fabricated by a sol-gel coating route. The crystallization of a deposited zirconia percursor thin layer and further phase transformation of tetragonal grains were shown to exhibit rather different behaviour from that of the free xerogel. The precursor layer and tetragonal zirconia grains were observed and imaged by transmission electron microscopy.
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Abstract Sols and gels (2SiO2 Al2O3) have been prepared by hydrolysis-condensation of a double alcoxyde in an alcoholic medium. Information concerning the chemical reactions has been previously obtained by 29Si and 27Al Nuclear Magnetic... more
Abstract Sols and gels (2SiO2 Al2O3) have been prepared by hydrolysis-condensation of a double alcoxyde in an alcoholic medium. Information concerning the chemical reactions has been previously obtained by 29Si and 27Al Nuclear Magnetic Resonance. This paper reports on the overall study of the growth of the polymers by small angle X-ray and neutron scattering and emphasizes the structural aspects.
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Nanocomposite ceramic materials were fabricated by conventional sintering of composite powders obtained by sol-gel coating of submicron powders. The microstructure of these MgAl2O4–ZrO2 materials was studied by transmission electron... more
Nanocomposite ceramic materials were fabricated by conventional sintering of composite powders obtained by sol-gel coating of submicron powders. The microstructure of these MgAl2O4–ZrO2 materials was studied by transmission electron microscopy. All zirconia grains were in the tetragonal phase. In addition, the intragranular zirconia crystals exhibited heteroepitaxial orientation relationships with the surrounding spinel grains, (hkl)zirconia//(hkl)spinel. Semi-coherent interfaces along {111} planes were observed by high-resolution microscopy. The transformation toward the orthorhombic or the monoclinic phase retained the epitaxial relationships as far as possible. The presence of such heteroepitaxial intragranular crystals in sintered ceramic materials, which did not involve a melting stage, was attributed to the specificity of the material preparation process.
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ABSTRACT
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A new and versatile method is proposed for the determination of strain profiles in epitaxic thin films. It is based on the simulation of the X-ray diffraction (XRD) profiles using cubic B-spline functions to model the vertical lattice... more
A new and versatile method is proposed for the determination of strain profiles in epitaxic thin films. It is based on the simulation of the X-ray diffraction (XRD) profiles using cubic B-spline functions to model the vertical lattice displacement profile. The lattice displacement profile, and consequently the strain profile, directly results from a least-square fit of the model to the experimental XRD profiles. Noa prioriassumption is made regarding the shape of the strain profile. Moreover, as spline functions are used, the recovered lattice displacement profile is smooth and exhibits a minimum curvature, thus avoiding oscillating or saw-toothed unphysical solutions. The potential of this method is illustrated with (100) yttria-stabilized zirconia epitaxic thin films deposited onto (11\bar{2}0) sapphire substrates by sol–gel processing.
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ABSTRACT
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Description d'un processus de stockage couple a la preparation d'un verre, a base de cordierite dans les proportions stœchiometriques, fabrique par le procede sol-gel
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A homemade x-ray diffractometer using one-dimensional position sensitive detector (PSD) and well suited to the study of thin epitaxial layer systems is presented. It is shown how PSDs can be advantageously used to allow fast reciprocal... more
A homemade x-ray diffractometer using one-dimensional position sensitive detector (PSD) and well suited to the study of thin epitaxial layer systems is presented. It is shown how PSDs can be advantageously used to allow fast reciprocal space mapping, which is especially interesting when analyzing poor crystalline and defective layers as usually observed with oxides and ceramics films. The quality of the data collected with such a setup and the limitations of PSDs in comparison with the use of analyzer crystals are discussed. In particular, the effects of PSD on angular precision, instrument resolution and corrections that must be applied to raw data are presented.
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ABSTRACT Reflectometry, diffraction and grazing incidence small angle X-ray scattering have been used to characterize zirconia (ZrO2) thin films obtained by the sol-gel route, during low temperature treatment. Different microstructural... more
ABSTRACT Reflectometry, diffraction and grazing incidence small angle X-ray scattering have been used to characterize zirconia (ZrO2) thin films obtained by the sol-gel route, during low temperature treatment. Different microstructural parameters of the films such as thickness, density, phase, grain size and spatial arrangement, have been determined. Thin films were formed on mirror-polished sapphire (Al2O3) wafers by a dip-coating process in a zirconia precursor sol. Before thermal treatment, the layer is amorphous and the thickness is about 140 nm. After thermal treatment at 600 °C during 30 minutes, the layer thickness decreases to 60 nm while the density increases, After crystallisation in the zirconia tetragonal form, the coating is made of randomly oriented nanocrystals. This structural evolution is similar to that of a conventional xerogel showing that the interface does not modify the microstructure of the layer. The nanocrystalline layer results in a relatively dense thin film.
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Investigation on the characteristics of x‐ray diffraction data for MgO powdered mixture of nano and sub‐nano particles has been carried out to reveal the crystallite‐size‐related microstructural information. The MgO powders were prepared... more
Investigation on the characteristics of x‐ray diffraction data for MgO powdered mixture of nano and sub‐nano particles has been carried out to reveal the crystallite‐size‐related microstructural information. The MgO powders were prepared by co‐precipitation method followed by ...
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ABSTRACT
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... 47-73 avenue Albert Thomas, 87065 Limoges Cedex, France $ Science des Procedes Ciramiques et de Traitements de Surfaces, Unite Mixte de Recherche associee au CNRS 6638, Facultk des Sciences, 123 avenue Albert Thomas, 87060 Limoges ...... more
... 47-73 avenue Albert Thomas, 87065 Limoges Cedex, France $ Science des Procedes Ciramiques et de Traitements de Surfaces, Unite Mixte de Recherche associee au CNRS 6638, Facultk des Sciences, 123 avenue Albert Thomas, 87060 Limoges ... (1982) and Delhez et al. ...
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Investigation on the characteristics of x‐ray diffraction data for MgO powdered mixture of nano and sub‐nano particles has been carried out to reveal the crystallite‐size‐related microstructural information. The MgO powders were prepared... more
Investigation on the characteristics of x‐ray diffraction data for MgO powdered mixture of nano and sub‐nano particles has been carried out to reveal the crystallite‐size‐related microstructural information. The MgO powders were prepared by co‐precipitation method followed by ...
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... Sci. Instrum. 48, 13031305. GabrielA., DauvergneF., and RosenbaumC. (1978). Linear, circular and two dimensional position sensitive detectors, Nucl. Instrum. ... Chem. 97, 95509554. SarrazinP., BlakeD., FeldmanS., ChiperaS.,... more
... Sci. Instrum. 48, 13031305. GabrielA., DauvergneF., and RosenbaumC. (1978). Linear, circular and two dimensional position sensitive detectors, Nucl. Instrum. ... Chem. 97, 95509554. SarrazinP., BlakeD., FeldmanS., ChiperaS., VanimanD., and BishD. (2005b). ...