Experimental Method of Determination of Structural Correlations in Surface Layers of Oxide Glass

1990 ◽  
Vol 216 ◽  
Author(s):  
Zenon BochyŃski
Keyword(s):  
Structural Changes ◽  
Lattice Models ◽  
Molecular Size ◽  
Oxide Glass ◽  
X Ray Diffraction ◽  
Surface Layers ◽  
X Ray ◽  
The Real ◽  
Inorganic Glasses

ABSTRACTA new method of X-ray diffraction analysis of structural inhomogeneities in the quartz/Si02/n based inorganic glasses is presented. The method enables the determination of structural changes occuring in the real nodal lattice in the regions of 10…20 Å or more as well as substructural changes in the regions 5…15 Å comparable to the molecular size of SiO2…SiO4. In consequence these changes can be correlated with approximate nodal lattice models of different degree of ordering. The applied method provided the possibility of constructing structural models of nodal lattices describing the surface and inner layers of the real glasses, changes in the local inhomogeneities as well as boundaries in water-gel associates.

scholarly journals Photocrystallography

2007 ◽  
Vol 64 (1) ◽  
pp. 259-271 ◽  
Author(s):  
Jacqueline M. Cole
Keyword(s):  
Structural Changes ◽  
Three Dimensional ◽  
Research Area ◽  
Active Species ◽  
X Ray Diffraction ◽  
X Ray ◽  
Future Possibility ◽  
New Research ◽  
Exciting Area

This review describes the development and application of a new crystallographic technique that is starting to enable the three-dimensional structural determination of molecules in their photo-activated states. So called `photocrystallography' has wide applicability, particularly in the currently exciting area of photonics, and a discussion of this applied potential is put into context in this article. Studies are classified into four groups: photo-structural changes that are (i) irreversible; (ii) long-lived but reversible under certain conditions; (iii) transient with photo-active lifetimes of the order of microseconds; (iv) very short lived, existing at the nanosecond or even picosecond level. As photo-structural changes relative to the `ground state' can be subtle, this article necessarily concentrates on small-molecule single-crystal X-ray diffraction given that high atomic resolution is possible. That said, where it is pertinent, references are also made to related major advances in photo-induced macromolecular crystallography. The review concludes with an outlook on this new research area, including the future possibility of studying even more ephemeral, femtosecond-lived, photo-active species.

A determination of structural evolution during the processing of glycol-based, sol-gel derived ceramics through the study of ferrimagnetic interactions

2007 ◽  
Vol 22 (11) ◽  
pp. 3152-3157 ◽  
Author(s):  
Edward J. Donahue ◽  
Michael Ng ◽  
Patrick Li
Keyword(s):  
Thermogravimetric Analysis ◽  
Structural Changes ◽  
Sol Gel ◽  
Structural Evolution ◽  
X Ray Diffraction ◽  
Straight Chain ◽  
X Ray ◽  
Decomposition Pathway ◽  
Ferrimagnetic Ordering

This work studies the chemical and structural changes that occur in sols upon heating to form ceramics. Ferrimagnetic Y3Fe5O12 (YIG) was chosen because the geometric and structural constraint of ferrimagnetic interactions allow for a direct measurement of the degree of well-defined structure present within the sol at various stages of development. Glycolate sols of 8% mol total metal were prepared using Y(NO3)3 and Fe(NO3)3 hydrates in stoichiometric ratios. Terminal straight-chain diols were used, ranging from 1,2-ethanediol to 1,6-hexanediol. The temperatures at which mass change occurred during heating were determined by thermogravimetric analysis. Samples were heated to these temperatures and examined by Fourier transform infrared spectroscopy (FTIR), x-ray diffraction, and magnetometry to determine chemical, structural, and magnetic changes. Ferrimagnetic ordering was present after the first heating step. Defined structure, determined by x-ray, occurred in the penultimate step. Analysis of FTIR spectra, in conjunction with the results of thermogravimetric analysis, revealed a predictable decomposition pathway.

Structural Inhomogeneities Of SiO2 Quartz Gláss

1987 ◽  
Vol 105 ◽  
Author(s):  
Zenon Bochyński
Keyword(s):  
Amorphous Materials ◽  
Structural Parameters ◽  
Direct Determination ◽  
Great Success ◽  
X Ray Diffraction ◽  
Crystalline Materials ◽  
X Ray ◽  
Accuracy Of Results ◽  
Inorganic Glasses

AbstractTill now the only effective method of direct determination of structural parameters has been X-ray diffraction structural analysis. This method applied to crystalline materials has proved a great success and applied to noncrystalline substances like for example inorganic glasses, is becoming more and more successful.Beginning with the W. Ostwald proposition /1913/ carried out by W. Friedrich /1913/ and P. Debye /1915/ through the papers by B.E. Warren et al. /1934–1942/ or by E.A. Poray-Koshits et al. /1934–1942/ till the most recently published papers devoted to structural studies of noncrystalline /amorphous/ materials we follow a significant progress in technology and methodology of these studies.The resulting significant improvement to the accuracy of results yields much more accurate structural models of non-crystalline materials.

scholarly journals Structure and Properties of Surface Layers: X-ray Diffraction Studies

1988 ◽  
Vol 41 (2) ◽  
pp. 261 ◽  
Author(s):  
R Delhez ◽  
ThH de Keijser ◽  
EJ Mittemeijer ◽  
BJ Thijsse ◽  
MA Hollanders ◽  
...  
Keyword(s):  
Diffraction Analysis ◽  
Structural Changes ◽  
Diffusion Processes ◽  
Bulk Material ◽  
Effective Diffusion ◽  
Solid Material ◽  
X Rays ◽  
X Ray Diffraction ◽  
Surface Layers ◽  
X Ray

Because X-rays are strongly absorbed on propagation through solid material, X-ray diffraction analysis can be fruitfully applied in the study of surface layers. After a brief discussion of some aspects of X-ray diffraction analysis of surface layers, attention is focussed on investigations of stress development and interdiffusion in surface layers. The behaviour of surface layers depends largely on their state of (residual) macro- and microstress. The development and possible relaxation of macrostress in surface layers can originate from the thermally imposed difference in shrink or expansion between layer and substrate, from developing concentration profiles and from structural changes, in particular phase transformations. Diffusion processes in multilayers, composed of alternately stacked sublayers of elements A and B, are highly affected by the multitude of interfaces and therefore differ from those in bulk material. The effective diffusion coefficients can be determined from the decrease of the intensity of the reflections corresponding to the composition-modulation period [so-called (000) satellites], and the change of the integrated intensities of reflections from produced or retained crystalline components. Examples of interdiffusion in an amorphous multilayer (in conjunction with structural relaxation) and in a crystalline multilayer (leading to amorphisation) are presented.

Sem and X-Ray Analysis of Renal and Biliary Calculi

1976 ◽  
Vol 34 ◽  
pp. 306-307
Author(s):  
R. J. Narconis ◽  
G. L. Johnson
Keyword(s):  
Chemical Constituents ◽  
Natural State ◽  
X Ray Diffraction ◽  
Chemical Methods ◽  
X Ray ◽  
Additional Dimension ◽  
Biliary Calculi ◽  
Calculus Formation ◽  
Scanning Electron

Analysis of the constituents of renal and biliary calculi may be of help in the management of patients with calculous disease. Several methods of analysis are available for identifying these constituents. Most common are chemical methods, optical crystallography, x-ray diffraction, and infrared spectroscopy. The application of a SEM with x-ray analysis capabilities should be considered as an additional alternative.A scanning electron microscope equipped with an x-ray “mapping” attachment offers an additional dimension in its ability to locate elemental constituents geographically, and thus, provide a clue in determination of possible metabolic etiology in calculus formation. The ability of this method to give an undisturbed view of adjacent layers of elements in their natural state is of advantage in determining the sequence of formation of subsequent layers of chemical constituents.

New Coordination Compounds of Fe(III) with Organic Ligands

2009 ◽  
Vol 59 (12) ◽  
Author(s):  
Mihaela Flondor ◽  
Ioan Rosca ◽  
Doina Sibiescu ◽  
Mihaela-Aurelia Vizitiu ◽  
Daniel-Mircea Sutiman ◽  
...  
Keyword(s):  
Chemical Analysis ◽  
Complex Compounds ◽  
Organic Ligands ◽  
X Ray Diffraction ◽  
X Ray ◽  
Elemental Chemical Analysis ◽  
Structural Formulae ◽  
Paramagnetic Properties

In this paper the synthesis and the study of some complex compounds of Fe(III) with ligands derived from: 2-(4-chloro-phenylsulfanyl)-1-(2-hydroxy-3,5-diiodo-phenyl)-ethanone (HL1), 1-(3,5-dibromo-2-hydroxy-phenyl)-2-phenylsulfanyl-ethanone(HL2), and 2-(4-chloro-phenylsulfanyl)-1-(3,5-dibromo-2-hydroxy-phenyl)-ethanone (HL3) is presented. The characterization of these complexes is based on method as: the elemental chemical analysis, IR and ESR spectroscopy, M�ssbauer, the thermogravimetric analysis and X-ray diffraction. Study of the IR and chemical analysis has evidenced that the precipitates form are a complexes and the combination ratio of M:L is 1:2. The central atoms of Fe(III) presented paramagnetic properties and a octaedric hybridization. Starting from this precipitation reactions, a method for the gravimetric determination of Fe(III) with this organic ligands has been possible. Based on the experimental data on literature indications, the structural formulae of the complex compounds are assigned.

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