scholarly journals Poisson errors and adaptive rebinning in X-ray powder diffraction data

2018 ◽  
Vol 33 (4) ◽  
pp. 266-269 ◽  
Author(s):  
Marcus H. Mendenhall
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Data Sets ◽  
Powder Diffraction Data ◽  
Data Set ◽  
X Ray ◽  
Short Summary ◽  
Correct Assignment ◽  
Wide Range ◽  
Diffraction Patterns

This work provides a short summary of techniques for formally-correct handling of statistical uncertainties in Poisson-statistics dominated data, with emphasis on X-ray powder diffraction patterns. Correct assignment of uncertainties for low counts is documented. Further, we describe a technique for adaptively rebinning such data sets to provide more uniform statistics across a pattern with a wide range of count rates, from a few (or no) counts in a background bin to on-peak regions with many counts. This permits better plotting of data and analysis of a smaller number of points in a fitting package, without significant degradation of the information content of the data set. Examples of the effect of this on a diffraction data set are given.

X-Ray Powder Diffraction Study of 2,2′,2″ triamino-triethylamine-Ni(II)-di-thiocyanate by Transmission PSD Diffractometer and Rietveld Techniques

1991 ◽  
Vol 6 (3) ◽  
pp. 166-169
Author(s):  
Britta Lundtoft ◽  
Svend Erik Rasmussen
Keyword(s):  
Diffraction Study ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Internal Standard ◽  
Data Sets ◽  
Powder Diffraction Data ◽  
Data Set ◽  
X Ray ◽  
Lattice Constants ◽  
Deep Blue

AbstractX-Ray powder diffraction data for the compound 2,2′,2″-triamino-triethylamine-Ni(II)-di-thiocyanate were obtained by transmission diffractometric methods at 20°C - 22°C. Two data sets were collected with CuKα1 radiation (λ = 1.54056 Å) one with Si as an internal standard (a = 5.430825 Å) and one without.The deep blue crystals are orthorhombic of space group P212121. Peak positions were corrected by aid of the Si peaks in the first data set. Refinements of lattice constants from indexed reflections yielded the following values: a = 10.8524(18) Å; b = 14.7249(16) Å; c = 8.6511(11) Å; Dx = 1.542 Mg/m3. The second data set was used for a Rietveld refinement. The lattice constants obtained by this method are: a = 10.8451(5) Å; b = 14.7148 Å; c = 8.6447(4) Å.

ExtSym: a program to aid space-group determination from powder diffraction data

2008 ◽  
Vol 41 (6) ◽  
pp. 1177-1181 ◽  
Author(s):  
Anders J. Markvardsen ◽  
Kenneth Shankland ◽  
William I. F. David ◽  
John C. Johnston ◽  
Richard M. Ibberson ◽  
...  
Keyword(s):  
Error Estimates ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
National Laboratory ◽  
Powder Diffraction Data ◽  
Acta Cryst ◽  
Data Set ◽  
Crystal System ◽  
Wide Range ◽  
Integrated Intensities

Once unit-cell dimensions have been determined from a powder diffraction data set and therefore the crystal system is known (e.g.orthorhombic), the method presented by Markvardsen, David, Johnson & Shankland [Acta Cryst.(2001), A57, 47–54] can be used to generate a table ranking the extinction symbols of the given crystal system according to probability. Markvardsenet al.tested a computer program (ExtSym) implementing the method against Pawley refinement outputs generated using theTF12LSprogram [David, Ibberson & Matthewman (1992). Report RAL-92-032. Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, UK]. Here, it is shown thatExtSymcan be used successfully with many well known powder diffraction analysis packages, namelyDASH[David, Shankland, van de Streek, Pidcock, Motherwell & Cole (2006).J. Appl. Cryst.39, 910–915],FullProf[Rodriguez-Carvajal (1993).Physica B,192, 55–69],GSAS[Larson & Von Dreele (1994). Report LAUR 86-748. Los Alamos National Laboratory, New Mexico, USA],PRODD[Wright (2004).Z. Kristallogr.219, 1–11] andTOPAS[Coelho (2003). Bruker AXS GmbH, Karlsruhe, Germany]. In addition, a precise description of the optimal input forExtSymis given to enable other software packages to interface withExtSymand to allow the improvement/modification of existing interfacing scripts.ExtSymtakes as input the powder data in the form of integrated intensities and error estimates for these intensities. The output returned byExtSymis demonstrated to be strongly dependent on the accuracy of these error estimates and the reason for this is explained.ExtSymis tested against a wide range of data sets, confirming the algorithm to be very successful at ranking the published extinction symbol as the most likely.

Powder-diffraction data for several solid solutions with the compositions (CaxSr1−x)CuO2 and (CaxSr1−x)2CuO3

1995 ◽  
Vol 10 (4) ◽  
pp. 296-299 ◽  
Author(s):  
S. T. Misture ◽  
C. Park ◽  
R. L. Snyder ◽  
B. Jobst ◽  
B. Seebacher
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Powder Diffraction ◽  
Solid Solutions ◽  
Diffraction Data ◽  
Solid State Reaction ◽  
High Temperature Superconductors ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Diffraction Patterns

Several compositions of the solid solutions (CaxSr1−x)CuO2 and (CaxSr1−x)2CuO3, both of which are found as minor phases in the high-temperature superconductors, were prepared by solid-state reaction. X-ray powder-diffraction patterns for three compositions of (CaxSr1−x)CuO2 and two for (CaxSr1−x)2CuO3 are presented.

Update in a Rietveld analysis program for x-ray powder spectro-diffractometry

2003 ◽  
Vol 18 (1) ◽  
pp. 32-35 ◽  
Author(s):  
Yanan Xiao ◽  
Fujio Izumi ◽  
Timothy Graber ◽  
P. James Viccaro ◽  
Dale E. Wittmer
Keyword(s):  
Computer Program ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Analysis ◽  
Anomalous Scattering ◽  
Analysis Program ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Synchrotron Light ◽  
Diffraction Patterns

A computer program for refining anomalous scattering factors using x-ray powder diffraction data was revised on the basis of the latest version of a versatile pattern-fitting system, RIETAN-2000. The effectiveness of the resulting program was confirmed by applying it to simulated and measured powder-diffraction patterns of Mn3O4 taken at a synchrotron light source.

X-ray powder diffraction data for compound DyNiSn

1997 ◽  
Vol 12 (3) ◽  
pp. 134-135
Author(s):  
Liangqin Nong ◽  
Lingmin Zeng ◽  
Jianmin Hao
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Diffraction Patterns

The compound DyNiSn has been studied by X-ray powder diffraction. The X-ray diffraction patterns for this compound at room temperature are reported. DyNiSn is orthorhombic with lattice parameters a=7.1018(1) Å, b=7.6599(2) Å, c=4.4461(2) Å, space group Pna21 and 4 formula units of DyNiSn in unit cell. The Smith and Snyder Figure-of-Merit F30 for this powder pattern is 26.7(0.0178,63).

X-Ray Powder Diffraction Data and Crystal Refinement of a New Compound AlCrNi3Pr

2016 ◽  
Vol 850 ◽  
pp. 3-7
Author(s):  
Shu Hui Liu ◽  
Liu Qing Liang ◽  
Chang Sheng Qin ◽  
De Gui Li ◽  
Ling Min Zeng ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Structure Refinement ◽  
Structure Type ◽  
Hexagonal Structure ◽  
Powder Diffraction Data ◽  
Tungsten Electrode ◽  
X Ray ◽  
Diffraction Patterns

Rare earth-transition metal (R-T) intermetallics have been well used because of their excellent properties. The X-ray diffraction patterns of many new phases in the R-T system have not been extensively studied. A new compound AlCrNi3Pr was prepared by arc melting using non-consumable tungsten electrode under argon atmosphere, and then annealed at 1023K for 30 days. The X-ray powder diffraction data of AlCrNi3Pr was collected on a Rigaku SmartLab X-ray powder diffractometer. The powder patterns of the compound were indexed, and the structure refinement by using Rietveld method indicated that the AlCrNi3Pr compound crystallized in the hexagonal structure, space group P6/mmm (No.191) with PrNi5 structure type, a=b=5.0553(9) Ǻ, c=4.0763(6) Ǻ, V=90.22Ǻ3, Z=1, ρx=7.288g cm-3, the Smith–Snyder FOM F30=279.1(0.0044, 32) and the intensity ratio RIR=1.23.

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.

Powder Diffraction Data of Some Acentric Tartrates and Tartrato-Antimonates

1991 ◽  
Vol 6 (2) ◽  
pp. 107-110
Author(s):  
Markus Garsche ◽  
Ekkehart Tillmanns ◽  
Thomas Bauer ◽  
Reinhard X. Fischer ◽  
Ladislav Bohaty
Keyword(s):  
Aqueous Solutions ◽  
Single Crystals ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Crystal Data ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Optical Effects ◽  
Diffraction Patterns

AbstractSix acentric tartrates and tartrato-antimonates have been investigated by means of X-ray powder diffraction. Single crystals were obtained by evaporation from aqueous solutions. The compounds have attracted attention because of their electrostrictive and electro-optical effects. Complete crystal data for the six compounds are reported. X-ray powder diffraction patterns for Rb2C4H4O6 and Ca [Sb2{C4H2O6}2]·2H2O are given.

X-ray powder diffraction studies of fibrillar zinc trimolybdates ZnMo3O10·nH2O (n=3.75,5,10)

1999 ◽  
Vol 14 (4) ◽  
pp. 276-279
Author(s):  
Wiesław Łasocha ◽  
Wiesław Surga ◽  
Alicja Rafalska-Łasocha
Keyword(s):  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Lattice Parameters ◽  
Fiber Axis ◽  
Powder Diffraction Data ◽  
Parallel Fibers ◽  
X Ray ◽  
Space Groups ◽  
Diffraction Patterns

The X-ray powder diffraction data of polycrystalline fibrillar zinc trimolybdates ZnMo3O10·3.75H2O, ZnMo3O10·5H2O, and ZnMo3O10·10H2O, are reported. An uncommon diffraction pattern was recorded in the case of the “wet fibers” of ZnMo3O10·10H2O, which could be indexed assuming a model of parallel fibers with translation disorder along the fiber axis. The powder diffraction patterns, lattice parameters, space groups, and other data describing these compounds are presented in this paper.© 1999 International Centre for Diffraction Data.

New X-ray powder diffraction data for two triborates CsB3O5(CBO) and TlB3O5(TBO)

1999 ◽  
Vol 14 (3) ◽  
pp. 234-236 ◽  
Author(s):  
M. Touboul ◽  
N. Pénin ◽  
L. Seguin
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Powder Diffraction Data ◽  
Powder Diffraction File ◽  
Space Group ◽  
X Ray ◽  
Figures Of Merit ◽  
Diffraction Patterns ◽  
Better Than

Precise X-ray powder diffraction patterns of two isostructural triborates, CsB3O5(CBO) and TlB3O5(TBO), have been collected on a D5000 diffractometer with a primary monochromated beam (λ CuKα1=1.5406 Å). Refinement of indexed reflections in the space group P212121 led to: a=6.201(1) Å, b=8.514(2) Å, c=9.176(2) Å, Z=4, Dx=3.363 for CBO and a=5.2156(4) Å, b=8.2659(6) Å, c=10.2240(9) Å, Z=4, Dx=4.773 for TBO. The Smith–Snyder figures of merit are F30=53.0 (0.0101, 56) for CBO and F30=112.9 (0.0074, 36) for TBO. These values are much better than the previous ones published in Powder Diffraction File.

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