Advances in the Computer Indexing of Powder Patterns

1979 ◽  
Vol 23 ◽  
pp. 295-303
Author(s):  
Gordon S. Smith
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Computer Assisted ◽  
Powder Diffraction Data ◽  
Quality Of Data ◽  
Small Unit ◽  
Data Set ◽  
Computer Data ◽  
Crystal System

AbstractIndexing of powder-diffraction patterns by computer techniques has advanced to the state that it is now often possible to determine unit-cell dimensions and crystal system for an unknown material solely from its powder-diffraction data. This indexing is fully automated, proceeding directly from positions of observed diffraction lines as input, with decision-making steps being made by a computer. Ease of indexing depends on quality of data (accuracy and completeness), volume of the unit cell, and symmetry of the crystal system. In general, a powder pattern of a triclinic compound with a large unit cell requires a more accurate and complete data-set for successful indexing than does a cubic material having a small unit cell. Fortunately, data from a well-aligned diffractometer or Guinier camera ordinarily suffices for computer indexing. Because of systematic errors in the low-lying diffraction lines, data from the Debye-Scherrer technique usually are not adequate for computer indexing (except for the simpler cases). A brief review of the strategies/algorithms of some of the computer indexing codes now available is given. Criteria for assessing the reliability of a particular computer- assisted indexing are discussed. Finally, attention is directed toward future developments such as by automating the collection of powder- diffraction data, analyzing data by computer data processing, and increasing the speed and reliability of computer indexing.

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.

X-ray-diffraction data of Pb2(C2O4)(NO3)2·2H2O

1996 ◽  
Vol 11 (1) ◽  
pp. 7-8 ◽  
Author(s):  
Hee-Lack Choi ◽  
Nobuo Ishizawa ◽  
Naoya Enomoto ◽  
Zenbe-e Nakagawa
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Crystal System

X-ray powder-diffraction data for Pb2(C2O4)(NO3)2·2H2O were obtained. The crystal system was determined to be monoclinic. The unit-cell parameters were refined to a=10.613(2) Å, b=7.947(2) Å, c=6.189(1) Å, and β=104.48(2)°.

X-ray diffraction data of Ti2O2(C2O4)(OH)2·H2O

1994 ◽  
Vol 9 (3) ◽  
pp. 187-188 ◽  
Author(s):  
Hee-Lack Choi ◽  
Naoya Enomoto ◽  
Nobuo Ishizawa ◽  
Zenbe-e Nakagawa
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Crystal System

X-ray powder diffraction data for Ti2O2(C2O4)(OH)2·H2O were obtained. The crystal system was determined to be orthorhombic with space group C2221. The unit cell parameters were refined to a = 1.0503(2) nm, b = 1.5509(3) nm, and c = 0.9700(1) nm.

Powder Diffraction Data and Unit Cell of Kutnohorite

1988 ◽  
Vol 3 (3) ◽  
pp. 172-174 ◽  
Author(s):  
Laszlo Farkas ◽  
Beda H. Bolzenius ◽  
Georg Will
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Profile Analysis ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Powder Diffraction File ◽  
Data Set ◽  
Cell Parameters ◽  
Computer Controlled

AbstractX-ray powder diffraction data, unit cell parameters and chemical data published previously for kutnohorite, the manganese-rich double carbonate mineral, are critically evaluated and compared with new measurements on a specimen from Chvaletice, Czechoslovakia with a composition Ca (Mn0.64Mg0.23Fe0.13)(CO3)2. Data were collected with a computer controlled diffractometer and analysed with profile analysis techniques. The new powder diffraction data set yields much better data and unit cell parameters than the earlier ones given for kutnohorite on PDF 11-345 (Powder Diffraction File, 1987). A least-squares evaluation resulted in ao = 4.8518(3)Å and co = 16.217(2)Å.

Powder diffraction data of Ba0.5Sr0.5TiO(C2O4)2·5H2O

2001 ◽  
Vol 16 (2) ◽  
pp. 107-109
Author(s):  
G. Vanhoyland ◽  
S. Hoste ◽  
M. K. Van Bael ◽  
J. Mullens ◽  
L. C. Van Poucke
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Crystal System

Ba0.5Sr0.5TiO(C2O4)2·5H2O, which is used as a precursor for Ba0.5Sr0.5TiO3 (BST), has been characterized by X-ray powder diffraction. In accordance with the known structure of BaTiO(C2O4)2·yH2O, the crystal system was found to be monoclinic with unit cell parameters: a=1.3965(1) nm, b=1.3811(2) nm, c=1.3306(2) nm, and β=92.15(1)°. The space group is P21/n, ρ=2.292(2) g cm−3, and Z=8.

X-ray powder diffraction data for κ-Al2O3

1999 ◽  
Vol 14 (1) ◽  
pp. 61-63 ◽  
Author(s):  
M. Halvarsson ◽  
V. Langer ◽  
S. Vuorinen
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Theoretical Density ◽  
Powder Diffraction Data ◽  
Orthorhombic Crystal System ◽  
Orthorhombic Crystal ◽  
X Ray ◽  
Crystal System ◽  
Chemical Formulas

X-ray powder diffraction data for κ-Al2O3 are reported. It was concluded that κ-Al2O3 belongs to the orthorhombic crystal system with space group Pna21. The lattice parameters were found to be a=4.8351(3) Å, b=8.3109(5) Å, c=8.9363(3) Å. There are 16 Al3+ and 24 O2− in the unit cell, and thus the number of chemical formulas in the unit cell, Z, is 8. The volume V of the unit cell is equal to 359.09(6) Å3 and the theoretical density Dx is 3.772 g/cm3. The Smith–Snyder (F20) and the de Wolff (M20) values for these data are 136.1 (0.0059, 25) and 98.4, respectively.

Powder X-ray data for the solid solution [(NH4)3Al1−xFex/2Crx/2(C2O4)3] ·3H2O; 0.10≤x≤0.80

1996 ◽  
Vol 11 (1) ◽  
pp. 2-4
Author(s):  
Mohamed Ezahri ◽  
Georges Coffy ◽  
Bernard F. Mentzen
Keyword(s):  
Solid Solution ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Crystal System

X-ray powder diffraction data are reported for the [(NH4)3Al1−xFex/2Crx/2(C2O4)3]·3H2O solid solution. The crystal system is triclinic with space group P1. Refined unit-cell parameters are given for the compositions x=0.10, 0.50 and 0.80.

X-Ray Powder Diffraction Data of Bi2Mo3O12·nH2O (n = 4.75)

1990 ◽  
Vol 5 (4) ◽  
pp. 227-228 ◽  
Author(s):  
Yasushi Murakami ◽  
Nobuo Ishizawa ◽  
Hisao Imai
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Crystal System

AbstractX-ray powder diffraction data for Bi2Mo3O12·nH2O (n = 4.75) were obtained. The crystal system was determined to be monoclinic with space group P21or P21/m. The unit cell parameters were refined to a = 6.334(2) Å, b = 11.593(2) Å, c = 5.777(2) Å, and β= 113.166(8)°.

X-ray powder diffraction data for tetrazene nitrate monohydrate, C2H9N11O4

2021 ◽  
pp. 1-3
Author(s):  
J. Maixner ◽  
J. Ryšavý
Keyword(s):  
Cell Volume ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell Volume ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters

X-ray powder diffraction data, unit-cell parameters, and space group for tetrazene nitrate monohydrate, C2H9N11O4, are reported [a = 5.205(1) Å, b = 13.932(3) Å, c = 14.196(4) Å, β = 97.826(3)°, unit-cell volume V = 1019.8(4) Å3, Z = 4, and space group P21/c]. All measured lines were indexed and are consistent with the P21/c space group. No detectable impurities were observed.

Crystal data and X-ray powder diffraction data of 2,4-diiodo-4-nitrophenol (disophenol), C6H3I2NO3. More precise X-ray powder diffraction data of p-nitrophenol, C6H5NO3

1996 ◽  
Vol 11 (4) ◽  
pp. 301-304
Author(s):  
Héctor Novoa de Armas ◽  
Rolando González Hernández ◽  
José Antonio Henao Martínez ◽  
Ramón Poméz Hernández
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Crystal Data ◽  
Powder Diffraction Data ◽  
Space Group ◽  
X Ray ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Monoclinic Cell

p-nitrophenol, C6H5NO3, and disophenol, C6H3I2NO3, have been investigated by means of X-ray powder diffraction. The unit cell dimensions were determined from diffractometer methods, using monochromatic CuKα1 radiation, and evaluated by indexing programs. The monoclinic cell found for p-nitrophenol was a=6.159(2) Å, b=8.890(2) Å, c=11.770(2) Å, β=103.04(2)°, Z=4, space group P21 or P2l/m, Dx=1.469 Mg/m3. The monoclinic cell found for disophenol has the dimensions a=8.886(1) Å, b=14.088(2) Å, c=8.521(1) Å, β=91.11(1)°, Z=4, space group P2, P2, Pm or P2/m, Dx=2.438 Mg/m3.

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