Upgrading Sulfide Mineral Patterns for the ICDD Powder Diffraction File

1994 ◽  
Vol 38 ◽  
pp. 107-115
Author(s):  
G. J. McCarthy ◽  
D. G. Grier ◽  
P. Bayliss
Keyword(s):  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Essential Role ◽  
Experimental Methods ◽  
Sulfide Mineral ◽  
Powder Diffraction File ◽  
Mineral Powder

Abstract The majority of sulfide mineral patterns in the International Centre for Diffraction Data Mineral Powder Diffraction File have historically been of low quality (e.g., FN < 10 and qualitative intensities). A five-year study has resulted in upgrading approximately 20% of the poorer quality patterns and will triple the number of “star quality” patterns. This paper describes the experimental methods used to obtain these upgraded patterns. The essential role of diffraction pattern calculations and diffractogram simulations is stressed.

Tools for Electron Diffraction Pattern Simulation for the Powder Diffraction File

2011 ◽  
Vol 19 (1) ◽  
pp. 32-37 ◽  
Author(s):  
Joel Reid ◽  
David Crane ◽  
Justin Blanton ◽  
Cyrus Crowder ◽  
Soorya Kabekkodu ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
High Tech ◽  
Inorganic Crystal Structure Database ◽  
Powder Diffraction File ◽  
Flat File ◽  
Quality Checks ◽  
Quality Mark

Since the creation of the Joint Committee on Powder Diffraction Standards (JCPDS) over sixty years ago, the Powder Diffraction File (PDF) has been the key source of standard powder diffraction data for identification and analysis of materials of all types, from natural minerals and high-tech ceramics to metals and alloys and pharmaceuticals. Although this editorially reviewed database has been the mainstay for diffraction pattern reference for the x-ray powder diffraction community, recent developments provide information and tools for electron diffraction. In recent years, the International Centre for Diffraction Data (ICDD, formerly JCPDS) has transformed the flat-file format of the PDF to a more flexible relational database (RDB) format. The PDF has been greatly expanded to include calculated patterns from multiple collaborating databases, including the Inorganic Crystal Structure Database (FIZ Karlsruhe, Germany), the Linus Pauling File (MPDS, Vitznau, Switzerland), and the Cambridge Structural Database (CCDC, Cambridge, United Kingdom). A significant portion of its entries include atomic coordinates and a specific database dedicated to organic phases exists. All new entries for the ICDD databases undergo over 100 quality checks before inclusion, and a quality mark is assigned for each entry that passes.

Combined method forab initiostructure solution from powder diffraction data

1999 ◽  
Vol 32 (5) ◽  
pp. 864-870 ◽  
Author(s):  
H. Putz ◽  
J. C. Schön ◽  
M. Jansen
Keyword(s):  
Global Optimization ◽  
Potential Energy ◽  
Diffraction Pattern ◽  
Intermetallic Compounds ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Powder Diffraction Data ◽  
Combined Method ◽  
The Difference ◽  
Space Method

A new direct-space method forabinitiosolution of crystal structures from powder diffraction diagrams is presented. The approach consists of a combined global optimization (`Pareto optimization') of the difference between the calculated and the measured diffraction pattern and of the potential energy of the system. This concept has been tested successfully on a large variety of ionic and intermetallic compounds.

X-ray powder diffraction data for indium nitride

1999 ◽  
Vol 14 (4) ◽  
pp. 258-260 ◽  
Author(s):  
W. Paszkowicz
Keyword(s):  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Microwave Plasma ◽  
Indium Nitride ◽  
Plasma Source ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
Calculated Density ◽  
X Ray

X-ray powder diffraction pattern for InN synthesized using a microwave plasma source of nitrogen is reported. The data were obtained with the help of an automated Bragg-Brentano diffractometer using Ni-filtered CuKα radiation. The lattice parameters for the wurtzite-type unit cell are ao=3.5378(1) Å, co=5.7033(1) Å. The calculated density is 6.921±0.002 g/cm3.

X-ray powder diffraction data for the superconducting phase Tl0.5Pb0.5Sr2CaCu2O6.5+δ

1993 ◽  
Vol 8 (4) ◽  
pp. 249-250 ◽  
Author(s):  
Chan Park ◽  
Robert L. Snyder
Keyword(s):  
High Temperature ◽  
Molten Salt ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Superconducting Phase ◽  
Powder Diffraction Data ◽  
X Ray ◽  
High Temperature Superconducting

The X-ray powder diffraction pattern for a sample of the high-temperature superconducting phase Tl0.5Pb0.5Sr2CaCu2O6.5+δ has been determined. The sample was prepared by a molten salt technique and had a Tc of 96 K.

X-Ray Powder Diffraction Data for Wolfeite: (Fe0.59Mn0.40Mg0.01)2PO4(OH)

1989 ◽  
Vol 4 (1) ◽  
pp. 34-35 ◽  
Author(s):  
Diano Antenucci ◽  
Francois Fontan ◽  
Andre-Mathieu Fransolet
Keyword(s):  
Federal Republic ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Federal Republic Of Germany ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters

AbstractWolfeite (Fe0.59Mn0.40Mg0.01)2PO4(OH) from the Hagendorf-Sud pegmatite, Bavaria, Federal Republic of Germany, yields unit-cell parameters of: a = 12.319(1), b = 13.280(2), c = 9.840(1) Å and β = 108° 24(1). Dmeas. = 3.82(2); Dcalc. = 3.88. An indexed powder diffraction pattern is given.

On racemic and L-malates: a comparison of their crystal structures

2004 ◽  
Vol 219 (2) ◽  
Author(s):  
Michel Fleck ◽  
Ekkehart Tillmanns ◽  
Ladislav Bohatý ◽  
Peter Held
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Monoclinic Space Group ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Powder Diffraction File ◽  
Space Group ◽  
X Ray

AbstractThe crystal structures of eight different L-malates have been determined and refined from single-crystal X-ray diffraction data. The compounds are the monoclinic (space groupIn addition, for all the compounds, powder diffraction data were collected, analysed and submitted to the powder diffraction file (PDF).

On the Need for Users of the Powder Diffraction File to Update Regularly

1987 ◽  
Vol 2 (2) ◽  
pp. 84-87 ◽  
Author(s):  
Ron Jenkins ◽  
Mark Holomany ◽  
Winnie Wong-Ng
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Review Process ◽  
Quality Of Data ◽  
Powder Diffraction File ◽  
Editorial Review

AbstractThe International Centre for Diffraction Data has an ongoing program to ensure the quality of data in the Powder Diffraction File (PDF) reflects current requirements of the powder diffraction community. Annual updates are made available, comprising of around 1800 new patterns and 200 replacement patterns, but current statistics indicate that only about 20% of users of the PDF take advantage of these updates. This paper reviews changes which have been inplemented in the editorial review process to continuously monitor and review pattern quality and gives examples of better data which have resulted from these changes.

Constraint-induced direct phasing method

2017 ◽  
Vol 73 (1) ◽  
pp. 54-60
Author(s):  
Hongliang Xu
Keyword(s):  
Single Crystal ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structural Information ◽  
Initial Structure ◽  
X Rays ◽  
Structural Refinement ◽  
Low Resolution ◽  
Crystallization Experiments

The best and most detailed structural information is obtained when the diffraction pattern of a single crystal a few tenths of a millimetre in each dimension is analyzed, but growing high-quality crystals of this size is often difficult, sometimes impossible. However, many crystallization experiments that do not yield single crystals do yield showers of randomly oriented microcrystals that can be exposed to X-rays simultaneously to produce a powder diffraction pattern. Although single-crystal diffraction data consist of discrete spots or X-ray reflections, the diffraction of microcrystals in a powder forms rings so that the reflections overlap. Thus, the analysis is more challenging due to unavoidable errors in the structure-factor amplitudes and the low-resolution data available for structure determination. This paper introduces a constraint-induced phasing method that (i) improves structure solutions measured by success rate, quality of solutions and various figures of merit, and (ii) extends low-resolution powder diffraction data to atomic resolution by adding unmeasured reflections. Application results have shown clearly that the constraint-induced phasing method is an effective way to produce initial structure models that are suitable for further structural refinement and completion.

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