Studying Structure of Metallic Superlattices by "Symmetric" and "Asymmetric" X-rAY Diffraction

1993 ◽  
Vol 308 ◽  
Author(s):  
G. Gladyszewski ◽  
Ph. Goudeau ◽  
K.F. Badawi ◽  
A. Naudon
Keyword(s):  
Atomic Structure ◽  
General Procedure ◽  
Structural Disorder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Superlattice Structure ◽  
Complete Determination ◽  
Psi Method

ABSTRACT"Symmetric" and "asymmetric" x-ray diffraction measurements are proposed as a tool for quantitative and complete determination of the superlattice structure. A general procedure which takes into account the atomic structure of the sublayers as well as structural disorder are presented. The "asymmetric" geometry using the "sin2psi" method is particularly emphasized.

Quantitative X-Ray Structure Determination of Superlattices and Interfaces

1991 ◽  
Vol 229 ◽  
Author(s):  
Ivan K. Schuller ◽  
Eric E. Fullerton ◽  
H. Vanderstraeten ◽  
Y. Bruynseraede
Keyword(s):  
General Procedure ◽  
Structural Refinement ◽  
X Ray Diffraction ◽  
Diffraction Profile ◽  
X Ray ◽  
Superlattice Structure ◽  
Wide Range ◽  
Fitting Algorithm ◽  
Superlattice Structures

AbstractWe present a general procedure for quantitative structural refinement of superlattice structures. To analyze a wide range of superlattices, we have derived a general kinematical diffraction formula that includes random, continuous and discrete fluctuations from the average structure. By implementing a non-linear fitting algorithm to fit the entire x-ray diffraction profile, refined parameters that describe the average superlattice structure, and deviations from this average are obtained. The structural refinement procedure is applied to a crystalline/crystalline Mo/Ni superlattices and crystalline/amorphous Pb/Ge superlattices. Roughness introduced artificially during growth in Mo/Ni superlattices is shown to be accurately reproduced by the refinement.

Exact determination of superlattice structure by small-angle x-ray diffraction

1988 ◽  
Vol 93 (1-4) ◽  
pp. 318-322 ◽  
Author(s):  
M. Sugawara ◽  
M. Kondo ◽  
S. Yamazaki ◽  
K. Nakajima
Keyword(s):  
Small Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Superlattice Structure ◽  
Exact Determination

Atomic Structure of Rare Earth Si-Al-O-N Glasses

1998 ◽  
Vol 53 (5) ◽  
pp. 259-264 ◽  
Author(s):  
H. Uhlig ◽  
M.-J. Hoffmann ◽  
S. Steeb
Keyword(s):  
Rare Earth ◽  
Neutron Diffraction ◽  
Atomic Structure ◽  
Pair Correlation ◽  
X Ray Diffraction ◽  
Ionic Radii ◽  
X Ray ◽  
Structure Factors ◽  
Total Structure

Abstract In this paper the results of X-ray diffraction experiments of Ln-Si-Al-O-N (Ln = La, Gd, Yb) glasses are presented. Total structure factors and pair correlation functions allow the determination of the first coordination sphere of Ln atoms. The bond lengths observed correspond to the ionic radii of the Ln-ions surrounded by oxygen and nitrogen atoms. The presence of non-bridging nitrogen is discussed together with results of neutron diffraction, NMR-experiments and XPS-studies of other authors.

THE GROWTH AND ATOMIC STRUCTURE OF THALLIUM ON COPPER(001)

1997 ◽  
Vol 04 (06) ◽  
pp. 1191-1196
Author(s):  
C. L. NICKLIN ◽  
C. NORRIS ◽  
C. BINNS ◽  
N. JONES ◽  
J. ALVAREZ ◽  
...  
Keyword(s):  
Atomic Structure ◽  
Ultrathin Films ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Temperature Growth ◽  
X Ray

We report a determination of the room temperature growth and atomic structure of ultrathin films of thallium on copper(001) using surface X-ray diffraction. The results show clearly that the growth is layerwise up to two monolayers and islanded thereafter. This is contrary to earlier reports which suggested that the islanding commenced at one monolayer. The first submonolayer structure to appear is a c(4×4) arrangement. Reflectivity scans suggest that there is significant reordering of the substrate at this coverage.

Antiphase Boundaries in Ordered Ni3FE Crystals

1969 ◽  
Vol 27 ◽  
pp. 62-63
Author(s):  
Y. H. Liu
Keyword(s):  
Domain Size ◽  
Antiphase Domain ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hardening Mechanism ◽  
Superlattice Structure ◽  
Disordered Phase ◽  
Domain Boundaries ◽  
Atomic Scattering ◽  
The Difference

Ordered Ni3Fe crystals possess a LI2 type superlattice similar to the Cu3Au structure. The difference in slip behavior of the superlattice as compared with that of a disordered phase has been well established. Cottrell first postulated that the increase in resistance for slip in the superlattice structure is attributed to the presence of antiphase domain boundaries. Following Cottrell's domain hardening mechanism, numerous workers have proposed other refined models also involving the presence of domain boundaries. Using the anomalous X-ray diffraction technique, Davies and Stoloff have shown that the hardness of the Ni3Fe superlattice varies with the domain size. So far, no direct observation of antiphase domain boundaries in Ni3Fe has been reported. Because the atomic scattering factors of the elements in NijFe are so close, the superlattice reflections are not easily detected. Furthermore, the domain configurations in NioFe are thought to be independent of the crystallographic orientations.

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.

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