Search results for " diffraction"
showing 10 items of 896 documents
Ab initiothermodynamics ofBacSr(1−c)TiO3solid solutions
2005
Based on ab initio calculations for a number of the ${\mathrm{Ba}}_{\mathrm{c}}{\mathrm{Sr}}_{(1\ensuremath{-}\mathrm{c})}\mathrm{Ti}{\mathrm{O}}_{3}$ (BST) superlattices, we developed a thermodynamic approach to these solid solutions. In particular, we calculate the BST phase diagram and show that at relatively low temperatures (below $400\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ for $c=0.5$ and $300\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ for $c=0.1$) the spinodal decomposition of the solid solution occurs. As a result, we predict for small Ba concentrations formation of $\mathrm{Ba}\mathrm{Ti}{\mathrm{O}}_{3}$ nanoregions in a predominantly $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_{3}$ matrix and …
Synthesis, UV/vis, FT-IR and Mössbauer spectroscopic characterization and molecular structure of the Bis[4-(2-aminoethyl)morpholine](tetrakis(4-metox…
2016
International audience; The synthesis, the UV-visible, FT-IR and Mossbauer spectroscopy and the crystal structure characterizations of the bis[4-(2-Aminoethyl)morpholine]tetrakis(4-metoxyphenyl)porphy-rinato)iron(II) complex are described. The title compound crystallizes in the triclinic, space group P-1, with a = 11.1253(4) angstrom, b = 11.2379(4) angstrom, c = 11.5488(4) angstrom, alpha = 72.304(2)degrees, beta = 86.002(2)degrees gamma = 72.066(2)degrees, V = 1308.28(8) angstrom(3), Z = 1. The Mossbauer data are consistent with an iron(II) low-spin (S = 0) porphyin species. The spin-state is confirmed by the value of the average equatorial iron-nitrogen pyrrole distance (Fe-Np = 1.988(2)…
Correlating Solution‐ and Solid‐State Structures of Conformationally Flexible Resorcinarenes: Significance of a Sulfonyl Group in Intramolecular Self…
2020
Abstract The synthesis of tetramethoxyresorcinarene podands bearing p‐toluene arms connected by ‐SO3‐ (1) and ‐CH2O‐ (2) linkers is presented herein. In the solid state, the resorcinarene podand 1 forms an intramolecular self‐inclusion complex with the pendant p‐toluene group of a podand arm, whereas the resorcinarene podand 2 does not show self‐inclusion. The conformations of the flexible resorcinarene podands in solution were investigated by variable‐temperature experiments using 1D and 2D NMR spectroscopic techniques as well as by computational methods, including a conformational search and subsequent DFT optimisation of representative structures. The 1H NMR spectra of 1 and 2 at room te…
Determination of surface and interface magnetic properties for the multiferroic heterostructure Co/BaTiO3using spleed and arpes
2016
Co/BaTiO$_3$(001) is one of the most interesting multiferroic heterostructures as it combines different ferroic phases, setting this way the fundamentals for innovative technical applications. Various theoretical approaches have been applied to investigate the electronic and magnetic properties of Co/BaTiO$_3$(001). Here we determine the magnetic properties of 3 ML Co/BaTiO$_3$ by calculating spin-polarized electron diffraction as well as angle-resolved photoemission spectra, with both methods being well established as surface sensitive techniques. Furthermore, we discuss the impact of altering the BaTiO$_3$ polarization on the spectra and ascribe the observed changes to characteristic deta…
Measuring Multiple Residual-Stress Components using the Contour Method and Multiple Cuts
2009
The conventional contour method determines one component of residual stress over the cross section of a part. The part is cut into two, the contour (topographic shape) of the exposed surface is measured, and Bueckner’s superposition principle is analytically applied to calculate stresses. In this paper, the contour method is extended to the measurement of multiple residual-stress components by making multiple cuts with subsequent applications of superposition. The theory and limitations are described. The theory is experimentally tested on a 316L stainless steel disk with residual stresses induced by plastically indenting the central portion of the disk. The multiple-cut contour method resu…
Application of fractal geometry to dissolution kinetic study of a sweetener excipient
2001
Abstract In the context of relationship study between dissolution kinetic and particle morphology using the fractal geometry tool, we use a commercially available quality of saccharin powder. The characterization of molecular feature and image analysis study allows us to conclude to the statistic self-similarity of particles of four sieved particles size fractions, permitting the fractal approach. Calculation of reactive fractal dimension is performed using two forms of mass transfer equation: −d Q /d t = kQ D R /3 Δ C and −d Q /d t = k′R D R −3 Δ C , with Δ C ={ C f /[ln C s /( C s − C f )]}. Based on comparison of the surface fractal dimension D S on the two values of reactive fractal di…
Different Dissolution Media Lead to Different Crystal Structures of Talinolol with Impact on Its Dissolution and Solubility
2003
During the performance of dissolution tests with immediate and controlled-release talinolol tablets it was detected that the type of the buffer used as dissolution medium had a strong influence on the solubility and the dissolution behavior of the drug. It was proven that talinolol appeared in different crystal structures with strongly differing solubilities when pure water, acetate, or phosphate buffers were employed as dissolution media. The resulting crystal structures were characterized by means of light microscopy, differential scanning calorimetry, and X-ray powder diffraction. All methods were adjuvant to detect changes in talinolol crystal structures. The different solubility and di…
Electron Crystallography in Mineralogy and Materials Science
2006
The mineral aerinite is investigated by electron crystallography (NED and HREM). TEM results of aerinite are compared with X-ray and synchrotron powder diffraction data. Six selected area electron diffraction (SAED) patterns and two HREM images from Pb5MoO8 single crystals are used to solve their structure. The unit cell parameters of these crystals confirm the known powder diffraction data.
Self-assembled MgxZn1−xO quantum dots (0 ≤ x ≤ 1) on different substrates using spray pyrolysis methodology
2013
By using the spray pyrolysis methodology in its classical configuration we have grown self-assembled MgxZn1−xO quantum dots (size [similar]4–6 nm) in the overall range of compositions 0 ≤ x ≤ 1 on c-sapphire, Si (100) and quartz substrates. Composition of the quantum dots was determined by means of transmission electron microscopy-energy dispersive X-ray analysis (TEM-EDAX) and X-ray photoelectron spectroscopy. Selected area electron diffraction reveals the growth of single phase hexagonal MgxZn1−xO quantum dots with composition 0 ≤ x ≤ 0.32 by using a nominal concentration of Mg in the range 0 to 45%. Onset of Mg concentration about 50% (nominal) forces the hexagonal lattice to undergo a p…
Adsorption of m-Xylene on Prehydrated Zeolite BaX: Correlation between Temperature-Programmed Desorption and Low-Temperature Neutron Powder Diffract…
1999
Adsorption of m-xylene on partially hydrated zeolite BaX is studied by thermogravimetry, mass spectrometry, temperature-programmed desorption and neutron diffraction for different m-xylene loadings of the zeolite. Macroscopic and microscopic measurements, for both molecules, were correlated and relationships were found between the crystallographic positions of the adsorbed molecules on the zeolite and macroscopic properties such as the number and the area of the peaks in the desorption spectra for m-xylene or water. The influence of water molecules on the adsorption phenomenon of m-xylene on BaX zeolite was characterized. In particular, it was shown that the increase of the filling of the p…