Search results for "Diffraction"
showing 10 items of 1584 documents
Solidification of syndiotactic polystyrene by a continuous cooling transformation approach
2007
Syndiotactic polystyrene (sPS) was solidified from the melt under drastic conditions according to a continuous cooling transformation methodology developed by the authors, which covered a cooling rate range spanning from approximately 0.03 to 3000 °C/s. The samples produced, structurally homogeneous across both their thickness and surface, were analyzed by macroscopic methods, such as density, wide-angle X-ray diffraction (WAXD), and microhardness (MH) measurements. The density was strictly related to the phase content, as confirmed by WAXD deconvolution. The peculiar behavior encountered (the density first decreasing and then increasing with the cooling rate) was attributed to the singular…
High resolution X-ray diffraction, X-ray multiple diffraction and cathodoluminescence as combined tools for the characterization of substrates for ep…
2013
The goal of this work is to show the capability of X-ray multiple diffraction (XRMD) to be used in combination with high resolution X-ray diffraction (HRXRD) and cathodoluminescence (CL) as an easy and simple methodology to determine structural and surface defect-related characteristics of samples that could be used as substrates for epitaxial growth. For this study ZnO {0001}-oriented samples have been used in view of their use as substrates for homoepitaxy. The miscut and bending of the samples have been analyzed by measuring the position of the X-ray diffraction peaks. The presence of multiple crystallographic domains and their characteristics have been studied by HRXRD (from the allowed…
Synchrotron diffraction study of the isothermal oxidation of uranium dioxide at 250°C
2003
ABSTRACTThe structural evolution of UO2 during its oxidation to U3O8 at 250°C in air was studied by in-situ synchrotron X-ray diffraction on the D2AM-CRG beamline at ESRF. The aim of this study is to determine the phases that are likely to appear during the long-term storage of spent nuclear fuel. Our results are in disagreement with the literature in which the existence of an intermediate cubic phase is not reported. Instead, an α-U3O7 tetragonal phase (c/a < 1) was mentioned but not definitively observed. These previous interpretations may have been the result of poor instrumental resolution.
New insight into δ-Pu alloy oxidation kinetics highlighted by using in-situ X-ray diffraction coupled with an original Rietveld refinement method
2018
Abstract The reactivity of a δ-Pu alloy was studied under dry oxygen at different temperatures. Phase analysis has shown the presence of α-and β-Pu2O3, PuO2, as well as the destabilisation of the δ-phase. The oxidation kinetics were studied using in-situ X-ray diffraction coupled with an original method of Rietveld refinement enabling an individual monitoring of the growth of each oxide. The results have evidenced a parabolic stage resulting from the thickening of the α-Pu2O3 layer, in which a compressive stress state develops. This stage is followed by the linear growth of a porous PuO2 scale.
Noise-Assisted Crystallization of Opal Films
2012
International audience; An improvement of the crystal quality of opal fi lms self-assembled from polymer spheres in a moving meniscus using the agitation by white noise acoustic vibrations is demonstrated. A tenfold higher ordering of a hexagonal sphere packing in the (111) plane is achieved. This crystallization method, the mechanism of which is described in terms of the stochastic resonance, is a contrast to the widely used approach based on maintaining equilibrium conditions during the crystallization process. The precise quantifi cation of the incremental lattice order improvement as a function of acoustic noise intensity is achieved by calculating the probability of finding an opposite…
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.
X-ray diffraction line-broadening study on two vibrating, dry-milling procedures in kaolinites
2009
Due to the great technological importance of the microstructure of kaolinite, characterizing its evolution during dry milling of kaolin and analyzing the microstructural information obtained from different methods were the main aims of this work. The microstructural alteration of kaolinite is evaluated by X-ray diffraction and electron microscopy methods, comparing the results obtained and analyzing the correlations between them. The Warren-Averbach and Voigt-function methods of X-ray diffraction microstructural analysis have been applied successfully to the study of the effects of two different, vibrating-cup dry-milling configurations in the microstructure of kaolinite from the reflection…
Gas sensing properties of Zn-doped p-type nickel ferrite
2012
Abstract The influence of zinc ion to the NiFe2O4 p-type semiconductor gas response characteristics is demonstrated. For characterization of gas sensor material, synthesized by sol–gel auto combustion method, X-ray diffraction (XRD), scanning electron microscopy (SEM), DC resistance and impedance spectroscopy (IS) measurements were employed. The response change of Zn doped nickel ferrite is related to the interruption of hole hopping between nickel ions. This was improved by change of conductivity type with temperature and gas exposure.
Preparation and Electric Properties of Barium Zirconium Titanate Ceramic
2015
The relaxor behavior of barium zirconium titanate ceramics BaZr0.35Ti0.65O3 prepared by a conventional sintering process was investigated. The synthesized material was determined by an X-ray diffraction and scanning electron microscopy. Based on performed studies, the BaZr0.35Ti0.65O3 ceramic material has been identified as canonical relaxor, related to the Ti-rich polar regions. The freezing temperature Tf and activation energy Ea are calculated from the Vogel-Fulcher relationship.