Search results for "Microscope"
showing 10 items of 1412 documents
A multi-technique, micrometer- to atomic-scale description of a synthetic analogue of chukanovite, Fe-2(CO3)(OH)(2)
2014
International audience; A synthetic analogue of chukanovite Fe-2(CO3)(OH)(2) is formed during experimental work on iron-clay interactions simulating the cooling of containers in radioactive waste repositories. Despite its small size and the mixture with other minerals it is undoubtedly identified by X-Ray Diffraction, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy and Transmission Electron Microscopy. For the first time, the structural characterisation of a synthetic chukanovite is carried out thanks to the combination of Automated Diffraction Tomography and Precession Electron Diffraction. Refinement results and comparison with literature data show that the structure…
Relative proportions of rutile and pseudo-brookite phases in the Fe(III)-TiO2 system at elevated temperature
1997
Abstract The Fe(III)-TiO2 system has been studied at T ≥ 1023 K in the range of concentration 2–10 at.% of iron by powder X-ray diffraction, transmission and scanning electron microscopy, and optical microscopy. The relationship between the relative proportions of the TiO2 rutile phase and the pseudo-brookite phase Fe2TiO5, has been investigated in powder samples. Single crystals of pure rutile and rutile doped with 0.5 at.% of iron have been examined to elucidate the microstructures found in the powders. The results suggest that a low degree of solid solubility exists and that doped crystals contain planar faults on 101 planes.
Uniaxial Alignment of Polycyclic Aromatic Hydrocarbons by Solution Processing
2005
The self-organization of two polycyclic aromatic hydrocarbons with different aromatic core sizes, dodecylphenyl-substituted hexa-peri- hexabenzocoronene and an extended disk consisting of 96 carbon atoms 6-fold-alkyl-substituted, on the surface from solution has been investigated. Highly ordered surface layers of both materials could be obtained by the zone-casting technique, despite an apparently low self-organization in drop-cast films. The zone-cast films revealed high macroscopic uniaxial orientation of the columns with a molecular edge-on arrangement on the glass support as confirmed by polarized optical microscopy, UV-vis measurements in polarized light, high-resolution transmission e…
Theoretical study of an absorbing sample in infrared near-field spectromicroscopy
2004
Abstract This paper is devoted to study the near-field spectrometry in the infrared spectral range. To understand the behavior of the infrared light diffracted by an object, numerical calculations have been carried out with Fourier Modale (FM) method within R-matrix algorithm. We consider the case of three-dimensional system including a translational symmetry in one direction, where is included an homogenous layer in which is buried an absorbing object. Using an optical near-field analysis and by calculating the electric field intensity distribution, both of the thickness effect and the lateral size of the absorbing sample are investigated. It is found that the distribution of the intensity…
Electrical Characterization of the Fe-Doped BT Ceramics by an Impedance Spectroscopy
2015
The electric properties of the Fe - doped BaTiO3 ceramics was investigated as a function of frequency and temperature. The structure and morphology of investigated sample were characterized by an X-ray diffraction and scanning electron microscopy. The impedance measurements were carried out at the temperature ranging from 450 K to 600 K, and at the frequency range from 0.1 Hz to 10 MHz. Based on these parameters the electrical properties of the grains and grains boundaries were described. The bulk and grains boundaries resistance of ceramics and the thermal activation energies were determined.
Which tool to distinguish transient alumina from alpha alumina in thermally grown alumina scales?
2005
International audience; Alumina scales constitute excellent protective barriers when they form on alumina-forming steels. If they keep tightly adherent to the underlying substrate, they isolate it from the surrounding aggressive atmosphere at high temperature. The protectiveness of the alumina scale is highly dependant upon its growth mechanism. The nucleation and transformation of transient alumina (mainly g-Al2O3 and y-Al2O3) is known to play an important role on alumina scale formation. It is therefore fundamental to characterise these transient alumina especially during the early stages of the oxidation process. The morphology of the transient alumina was observed by scanning electron m…
Extractive-Pyrolytic Method for Au/MeO<sub>x</sub> Nanocomposites Production
2014
Au/MeOx(MeOx- SiO2, Al2O3and TiO2) nanocomposites have been produced by the extractive-pyrolytic method. An organic extract – a solution of n-trioctylammonium tetrachlorolaurate ([Oct3NH]AuCl4) in toluene – was used as a gold-containing precursor. The produced samples were analyzed by IR spectroscopy, X-ray diffraction and scanning electron microscopy. The performed studies have shown that the mean size of the metal crystallites vary within wide limits: on Al2O3from 60 nm to 35 nm; on SiO2from 33 nm to 23 nm; on TiO2from 50 nm to 13 nm.
SNOM study of ferroelectric domains in doped LiNbO3 crystals
2009
Abstract This work shows a study of the periodic ferroelectric domains formed in LiNbO3 crystals doped with rare earths by means of scanning near field optical microscopy (SNOM) technique. It has been observed periodic structures associated with ferroelectric domains with an unexpected high value of the optical contrast working under reflectance SNOM mode. From Raman-Nath diffraction patterns, a refractive index modulation of Δ n ∼ 1 0 − 4 has been calculated. These results were correlated with the ferroelectric periodic domains obtained by the SNOM technique. A light waveguide effects along the ferroelectric domains is suggested to explain the high reflectance contrast observed in SNOM exp…
Growth and characterization of Mg 1‐x Cd x O thin films
2016
In this paper, we study the growth of thin films of the Mg1–xCdxO alloy in the Mg-rich range of compositions by using the metal organic chemical vapour deposition (MOCVD) method at low pressure. X-ray diffraction (XRD) has been used to analyse the compound formation and the progressive incorporation of Cd2+ ions into the cubic MgO lattice. Both, layers with a single-cubic phase of Mg1–xCdxO and layers with a phase separation, where Cd1–xMgxO and Mg1–xCdxO coexist, have been studied. Finally, a morphological study of the layers has been carried out by using scanning electron microscopy (SEM) and the layers' composition has been measured by energy dispersive X-ray analysis (EDX). (© 2016 WILE…
Characterization of Dielectric Anomaly in Solid Solution Based on BaTiO3
2011
The influence of Zr doping on a structure and dielectric properties of Ba0.8Sr0.2TiO3 were studied. For this purpose Ba0.8Sr0.2Ti0.75Zr0.25O3 ceramics were obtained by a conventional method and were determined by an X-ray diffraction (XRD) and scanning electron microscopy (SEM) for crystallographic, surface morphological and compositional studies. The temperature and frequency dependence of dielectric permittivity were studied in the temperature range from 150 to 500 K and the frequency between 20 Hz and 1000000 Hz. The thermal behavior of the Ba0.8Sr0.2Ti0.75Zr0.25O3 ceramics were also studied using Differential Scanning Calorimetry. A diffusivity coefficient γ was calculated.