TexPat – a program for quantitative analysis of oblique texture electron diffraction patterns

2004 ◽  
Vol 219 (1) ◽  
Author(s):  
Peter Oleynikov ◽  
Sven Hovmöller ◽  
Xiaodong Zou ◽  
Anatoliy P. Zhukhlistov ◽  
Maxim S. Nickolsky ◽  
...  
Keyword(s):  
Automated Detection ◽  
Unit Cell ◽  
Published Data ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Symmetry Properties ◽  
Speed Up ◽  
Diffraction Patterns ◽  
Integrated Intensities

AbstractWe have developed a program – TexPat for quantification of texture patterns in order to facilitate, speed up and improve the accuracy of this analytical method. The program introduces new approaches for automated detection of centre and symmetry axes and simplifies the process of indexing and calculating the unit cell parameters. The main algorithm of the program uses the symmetry properties of the texture pattern images. The successive steps help to process the reflections of the pattern using the peak shape extracted from well-separated peaks. The program generates a list of unit cell parameters, all processed reflections with Miller indices and their integrated intensities. The quality of the results obtained by TexPat is compatible with published data.

The determination of unit-cell parameters from Laue diffraction patterns using their gnomonic projections

1992 ◽  
Vol 25 (2) ◽  
pp. 294-308 ◽  
Author(s):  
P. D. Carr ◽  
D. W. J. Cruickshank ◽  
M. M. Harding
Keyword(s):  
Diffraction Pattern ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Laue Diffraction ◽  
Cell Parameters ◽  
The Absolute ◽  
Diffraction Patterns

A method is described whereby the unit cell of a crystal and its orientation can be determined from a single Laue diffraction pattern (in transmission). The axial ratios and interaxial angles can be determined precisely, but the absolute scaling of the cell depends upon the accuracy with which the minimum wavelength for the experiment is known. Several examples are given.

X-ray powder diffraction data of anilinium trimolybdate tetrahydrate and anilinium trimolybdate dihydrate

1999 ◽  
Vol 14 (4) ◽  
pp. 280-283 ◽  
Author(s):  
A. Rafalska-Łasocha ◽  
W. Łasocha ◽  
M. Michalec
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Room Temperature ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Diffraction Patterns

The X-ray powder diffraction patterns of anilinium trimolybdate tetrahydrate, (C6H5NH3)2Mo3O10·4H2O, and anilinium trimolybdate dihyhydrate, (C6H5NH3)2Mo3O10·2H2O, have been measured in room temperature. The unit cell parameters were refined to a=11.0670(7) Å, b=7.6116(8) Å, c=25.554(3) Å, space group Pnma(62) and a=17.560(2) Å, b=7.5621(6) Å, c=16.284(2) Å, β=108.54(1)°, space group P21(4) or P21/m(11) for orthorhombic anilinium trimolybdate tetrahydrate and monoclinic anilinium trimolybdate dihydrate, respectively.

Systematic crystallographic refinement of triclinic unit cells

1998 ◽  
Vol 13 (1) ◽  
pp. 22-31
Author(s):  
Ludo K. Frevel
Keyword(s):  
Powder Diffraction ◽  
Unit Cell ◽  
Simultaneous Equations ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Triclinic Phase ◽  
Unit Cells ◽  
Diffraction Patterns ◽  
Limits Of Error

Combining the exhaustive indexing of triclinic powder diffraction patterns with a crystallographic determination of unit cell parameters from pinacoid and prism reflections yields unit cell parameters with realistic limits of error. Additionally a referee method has been developed by which the six reciprocal cell parameters of a triclinic phase are determined by solving an exhaustive set of linear simultaneous equations in six unknowns.

Powder-Pattern: A System of Programs for Processing and Interpreting Powder Diffraction Data

1982 ◽  
Vol 26 ◽  
pp. 63-72 ◽  
Author(s):  
Nikos P. Pyrros ◽  
Camden R. Hubbard
Keyword(s):  
Unit Cell ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Pure Phase ◽  
Diffraction Patterns ◽  
Better Than ◽  
Good Agreement

The production of standard x-ray diffraction patterns at NBS imposes special requirements in the data processing of powder patterns. The patterns should be complete and have an overall accuracy of better than 0.01 degree two theta. To ensure completeness all the observable peaks should be indexed. To make certain that the sample is a pure phase, weak peaks have to be identified as well.The indexing of all the peaks implies that the cell constants must be known and there should be a good agreement between all the calculated and observed peak positions. In practice this is achieved by a least-squares refinement of the unit cell parameters. This serves as a test of the assumed unit cell and also as an interpretation of the observed peaks. Finally, an attempt is made to identify the space group. This step also requires the identification of weak peaks. The agreement of a known space group with the observed reflections further confirms the purity of the sample.

RICICLE: A FORTRAN program to refine unit cell parameters of incommensurate structures

1993 ◽  
Vol 8 (3) ◽  
pp. 168-172 ◽  
Author(s):  
R. I. Smith
Keyword(s):  
Least Squares ◽  
Powder Diffraction ◽  
Fortran Program ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Full Matrix ◽  
Cell Parameters ◽  
Incommensurate Structures ◽  
Diffraction Patterns ◽  
Modulation Vector

A FORTRAN 77 program to perform full matrix least-squares refinement of unit cell parameters from powder diffraction patterns showing incommensurate supercell reflections is described. The code is completely general, being applicable to any crystal system, and can refine all three unit cell edges and angles and, in the presence of an incommensurate supercell, can refine the components of the modulation vector along all three reciprocal axes. Estimated standard deviations on all the refined parameters are calculated analytically.

X-ray powder diffraction pattern for lactitol and lactitol monohydrate

1994 ◽  
Vol 9 (3) ◽  
pp. 213-216 ◽  
Author(s):  
J. Valkonen ◽  
P. Perkkalainen ◽  
I. Pitkänen ◽  
H. Rautiainen
Keyword(s):  
Powder Diffraction ◽  
Least Squares Method ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Cell Dimensions ◽  
Diffraction Patterns ◽  
Unit Cell Dimensions

Diffraction patterns were recorded, and unit cell dimensions refined by the least-squares method, for lactitol and lactitol monohydrate. Refined unit cell parameters for lactitol are: a =7.622(1) Å, b = 10.764(2) Å, c = 9.375(1) Å, β= 108.25(1)° in space group P21, and those for lactitol monohydrate a =7.844(1) Å, b = 12.673(2) Å, c = 15.942(2) Å in space group P212121.

X-ray powder diffraction data for five lanthanoid chromates [Ln2(CrO4)3(H2O)5]·2H2O (Ln=La,Pr,Nd,Sm,Eu)

1994 ◽  
Vol 9 (2) ◽  
pp. 98-104
Author(s):  
Jaakko Leppä-aho ◽  
Jussi Valkonen
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Diffraction Patterns

X-ray powder diffraction data are reported for a series of isomorphous compounds of [Ln2(CrO4)3(H2O)5]·2H2O, where Ln=La, Pr, Nd, Sm, or Eu. The compounds crystallize in monoclinic space group P21/c (No: 14) with Z=4. Refined unit cell parameters and indexed powder diffraction patterns are given.

scholarly journals Precision lattice parameter determination from transmission diffraction of thick specimens with irregular cross sections

2019 ◽  
Vol 52 (1) ◽  
pp. 40-46 ◽  
Author(s):  
S. R. Stock ◽  
M. Laugesen ◽  
H. Birkedal ◽  
A. Jakus ◽  
R. Shah ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Unit Cell ◽  
Lattice Parameters ◽  
Parameter Determination ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
3D Printed ◽  
The Cross ◽  
Diffraction Patterns

Accurate determination of lattice parameters from X-ray diffraction requires that the diffraction angles be measured very precisely, and significant errors result if the sample–detector separation differs from that assumed. Transmission diffraction from bones, which have a complex cross section and must be left intact, is a situation where this separation is difficult to measure and it may differ from position to position across the specimen. This article describes a method for eliminating the effect of variable sample cross section. Diffraction patterns for each position on the specimen are collected before and after 180° rotation about an axis normal to the cross section of interest. This places the centroid of the diffracting mass at the center of rotation and provides the absolute lattice parameters from the average apparent lattice parameters at the two rotation angles. Diffraction patterns were collected across the cross section of three specimens: a 3D-printed elliptical cylinder of Hyperelastic Bone (HB), which is composed primarily of synthetic hydroxyapatite (hAp), a 3D-printed HB model of the second metacarpal bone (Mc2), and a modern human Mc2 containing nanocrystalline carbonated apatite (cAp). Rietveld refinement was used to determine precise unit-cell parameters a apparent and c apparent for each pattern of each scan, and these values determined the actual average 〈a〉 and 〈c〉 for each sample. The results indicate that the 0°/180° rotation method works well enough to uncover variations approaching 1 × 10−3 Å in cAp unit-cell parameters in intact bones with irregular cross sections.

Structure Studies of Electrodeposited Ni-Mo Alloys with Polymers after Annealing

2007 ◽  
Vol 130 ◽  
pp. 97-100 ◽  
Author(s):  
Małgorzata Karolus ◽  
Edward Rówiński ◽  
Eugeniusz Łągiewka
Keyword(s):  
Solid Solution ◽  
Steel Substrate ◽  
Argon Atmosphere ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Air Atmosphere ◽  
Diffraction Patterns

Electrolytical layers of Ni-Mo alloys with polypyrrole, polytiofene and polyethylene were deposited on steel substrate (St3S, 4 cm2). After structural analyses of as quenched samples performed by X-ray diffraction it was noticed that the solid solution of Mo in Ni is observed. After annealing in an argon atmosphere the solid solution of Mo in Ni is becomeing more stable and crystalites are growing to the size of 200 – 300 Å. After annealing in an air atmosphere X-ray diffraction patterns show presence of phases: NiO, MoO, NiCO3, Mo2N. The unit cell parameters of solid solution after annealing are smaller than parameters of as quenched samples what means that the solid solution has been decomposing.

Crystal data for benzofuroin

1983 ◽  
Vol 16 (1) ◽  
pp. 140-140
Author(s):  
O. Durruthy ◽  
F. Fajardo ◽  
R. Pomes
Keyword(s):  
Powder Diffraction ◽  
Unit Cell ◽  
Crystal Data ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Diffraction Patterns

Benzofuroin crystal data were obtained from X-ray powder diffraction patterns. Benzofuroin, C12H10O3, is monoclinic P21/c, with unit-cell parameters a = 10.672 (3), b = 16.521 (4), c = 5.586 (1) Å and γ = 110.45 (3)°, V= 922.8 (10) Å3, Z = 4, Dx = 1.45 Mgm−3.

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