Status of the reference X-ray powder-diffraction patterns for the serpentine minerals in the PDF database—1997

2000 ◽  
Vol 15 (1) ◽  
pp. 42-50 ◽  
Author(s):  
Fred J. Wicks
Keyword(s):  
Powder Diffraction ◽  
Poor Quality ◽  
Critical Examination ◽  
Current Pattern ◽  
Powder Diffraction File ◽  
X Ray ◽  
Serpentine Minerals ◽  
Diffraction Patterns ◽  
The Many ◽  
Identification Tool

A critical examination of the reference X-ray powder-diffraction patterns of the serpentine minerals in the Powder-Diffraction File (PDF) database has revealed an unsettling situation. Most of the patterns in, or previously in, the PDF database are inaccurate, misidentified, or of poor quality. The PDF database is not a dependable tool for identifying the serpentine minerals, and has not been since the mid-1960s. This has serious implications for studies on serpentine minerals that have depended on the PDF database, particularly those by nonmineralogists doing health and environmental studies of chrysotile asbestos. In the current PDF database, lizardite-1T, carlosturanite, some amesite, and possibly some antigorite (but with inappropriate polytype symbols) can be identified. Only one of the many multilayer lizardites can be identified. The current pattern for chrysotile-2Mc1 (clinochrysotile) is of reasonable quality, but not the best, however the earlier patterns still in the database are so problematic that any chrysotile-2Mc1 identification must be considered suspect. Chrysotile-2Oc1 (orthochrysotile), and any mixture of serpentines cannot be identified using the PDF database. Until the reference serpentine patterns are corrected the PDF database cannot be considered a reliable identification tool. High-quality powder-diffraction patterns of the serpentine minerals have been published and can be rapidly introduced into the PDF database.© 2000 International Centre for Diffraction Data.

Evaluation of Reference X-ray Diffraction Patterns in the ICDD Powder Diffraction File

1990 ◽  
Vol 34 ◽  
pp. 369-376
Author(s):  
G. J. McCarthy ◽  
J. M. Holzer ◽  
W. M. Syvinski ◽  
K. J. Martin ◽  
R. G. Garvey
Keyword(s):  
Powder Diffraction ◽  
X Ray Diffraction ◽  
Powder Diffraction File ◽  
Cd Rom ◽  
X Ray ◽  
Binary Oxides ◽  
Diffraction Patterns ◽  
Input Format ◽  
Good Agreement

AbstractProcedures and tools for evaluation of reference x-ray powder patterns in the JCPDSICDD Powder Diffraction File are illustrated by a review of air-stable binary oxides. The reference patterns are evaluated using an available microcomputer version of the NBS*A1DS83 editorial program and PDF patterns retrieved directly from the CD-ROM in the program's input format. The patterns are compared to calculated and experimental diffractograms. The majority of the oxide patterns have been found to be in good agreement with the calculated and observed diffractograms, but are often missing some weak reflections routinely observed with a modern diffractometer. These weak reflections are added to the PDF pattern. For the remainder of the phases, patterns are redetermined.

X-ray powder diffraction reference patterns for Bi1−xPbxOCuSe

2016 ◽  
Vol 31 (3) ◽  
pp. 223-228 ◽  
Author(s):  
W. Wong-Ng ◽  
Y. Yan ◽  
J.A. Kaduk ◽  
X.F. Tang
Keyword(s):  
Cell Volume ◽  
Powder Diffraction ◽  
Ionic Radius ◽  
Unit Cell Volume ◽  
Unit Cell ◽  
Powder Diffraction File ◽  
X Ray ◽  
Natural Superlattice ◽  
Diffraction Patterns ◽  
Pb Substitution

The structures and powder X-ray reference diffraction patterns of the “natural superlattice” series Bi1−xPbxOCuSe (x = 0, 0.02, 0.04, 0.06, 0.08, and 0.10) have been investigated. As the ionic radius of Pb2+ is greater than that of Bi3+, the unit-cell volume of Bi1−xPbxOCuSe increases progressively from x = 0 to 0.1, namely, from 137.868(5) to 139.172(11) Å3, as expected. The structure of Bi1−xPbxOCuSe is built from [Bi2(1−x)Pb2xO2]2(1−x)+ layers normal to the c-axis alternating with [Cu2Se2]2(1−x)− fluorite-like layers. Pb substitution in the Bi site of Bi1−xPbxOCuSe leads to the weakening of the “bonding” between the [Bi2(1−x)Pb2xO2]2(1−x)+ and the [Cu2Se2]2(1−x)− layers. Powder patterns of Bi1−xPbxOCuSe were submitted to be included in the Powder Diffraction File.

Powder X-Ray Data for Synthetic Anhydrous Sodium Zirconium Silicates

1987 ◽  
Vol 2 (3) ◽  
pp. 176-179 ◽  
Author(s):  
G. Wilson ◽  
F. P. Glasser
Keyword(s):  
Solid State ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Solid State Reaction ◽  
The Other ◽  
X Ray Diffraction ◽  
Powder Diffraction File ◽  
X Ray ◽  
Sodium Zirconium ◽  
Diffraction Patterns

AbstractA systematic survey of phase formation in the Na2O-ZrO2-SiO2 system has revealed inconsistencies in the number and identity of ternary phases, and of their X-ray powder data. The phases Na2ZrSiO5, Na4Zr2Si3O12, Na2ZrSi2O7 and Na2ZrSi4O11 were prepared by solid-state reaction and their experimental X-ray diffraction patterns measured. Calculated X-ray diffraction patterns were generated by computer, using published crystallographic data, and critically compared with the experimentally observed values. The unit-cell constants were redefined to a greater accuracy than the presently accepted values published in the Powder Diffraction File. Only Na4Zr2Si3O12 produced an X-ray diffraction pattern which agreed with that previously published; those from the other phases were significantly different in both the intensities and positions of the reflections. Data for synthetic Na2ZrSi4O11 identical to the mineral vlasovite are reported.

X-ray powder diffraction studies of (BaxSr1−x)2Co2Fe12O22 and (BaxSr1−x)Co2Fe16O27

2015 ◽  
Vol 30 (2) ◽  
pp. 139-148 ◽  
Author(s):  
W. Wong-Ng ◽  
G. Liu ◽  
Y. Yan ◽  
K. R. Talley ◽  
J. A. Kaduk
Keyword(s):  
Seebeck Coefficient ◽  
Powder Diffraction ◽  
Lattice Parameters ◽  
Hexagonal Ferrite ◽  
Layered Compounds ◽  
X Ray Diffraction ◽  
Powder Diffraction File ◽  
Space Group ◽  
X Ray ◽  
Diffraction Patterns

X-ray structural characterization and X-ray reference powder patterns have been determined for two series of iron- and cobalt-containing layered compounds (BaxSr1−x)2Co2Fe12O22 (x = 0.2, 0.4, 0.6, 0.8) and (BaxSr1−x)Co2Fe16O27 (x = 0.2, 0.4, 0.6, 0.8). The (BaxSr1−x)2Co2Fe12O22 series of compounds crystallized in the space group R$\bar 3$m (No. 166), with Z = 3. The structure is essentially that of the Y-type hexagonal ferrite, BaM2+Fe63+O11. The lattice parameters range from a = 5.859 15(8) to 5.843 72(8) Å, and c = 43.4975(9) to 43.3516(9) Å for x = 0.2 to 0.8, respectively. The (BaxSr1−x)Co2Fe16O27 series (W-type hexagonal ferrite) crystallized in the space group P63/mmc (No. 194) and Z = 2. The lattice parameters range from a = 5.902 05(12) to 5.8979(2) Å and c = 32.9002(10) to 32.8110(13) Å for x = 0.2 to 0.8. Results of measurements of the Seebeck coefficient and resistivity of these two sets of samples indicated that they are insulators. Powder X-ray diffraction patterns of these two series of compounds have been submitted to be included in the Powder Diffraction File.

Evaluation of Reference X-Ray Diffraction Patterns in the ICDD Powder Diffraction File

1991 ◽  
pp. 369-376
Author(s):  
G. J. McCarthy ◽  
J. M. Holzer ◽  
W. M. Syvinski ◽  
K. J. Martin ◽  
R. G. Garvey
Keyword(s):  
Powder Diffraction ◽  
X Ray Diffraction ◽  
Powder Diffraction File ◽  
X Ray ◽  
Diffraction Patterns

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.

Design and use of a prototype long-wavelength powder diffractometer

1993 ◽  
Vol 8 (2) ◽  
pp. 84-88
Author(s):  
Ron Jenkins ◽  
J. A. Nicolosi
Keyword(s):  
Powder Diffraction ◽  
Poor Quality ◽  
Inorganic Materials ◽  
Large Unit ◽  
X Ray ◽  
Long Wavelength ◽  
Angle Data ◽  
Unit Cells ◽  
Diffraction Patterns ◽  
Low Symmetry

The analysis of crystalline organic phases by X-ray powder diffraction presents special problems, beyond those typically associated with inorganic materials. The large unit cells often associated with organic compounds, combined with the low symmetry of the structures, give rather complicated diffraction patterns that contain many low angle lines. The Bragg–Brentano geometric arrangement employed in most commercial diffractometers gives maximum (d-spacing error at low diffraction angles. This geometry, in turn, means that not only can the large (d-spacing data be of poor quality, but also that much of the low angle data required for the indexing of the pattern is subject to large errors.

The ICDD/PDF Coverage of the High Tc Superconductor and Related Compounds in the A-R-Cu-O Systems (A = Ba, Sr and Ca, and R = Lanthanides and Y)

1992 ◽  
Vol 7 (3) ◽  
pp. 125-133 ◽  
Author(s):  
Winnie Wong-Ng
Keyword(s):  
Powder Diffraction ◽  
Cross Correlation ◽  
Reaction Products ◽  
Powder Diffraction File ◽  
High Tc ◽  
X Ray ◽  
High Tc Superconductor ◽  
Different Types ◽  
Diffraction Patterns ◽  
Related Compounds

AbstractA compilation has been made of the X-ray powder diffraction patterns of the high Tc superconductor and related phases in the systems of Ba-R-Cu-O, Sr-R-Cu-O and Ca-R-Cu-O, where R = yttrium and lanthanides. In addition to the patterns of compounds found in these systems, other related compounds included are cation substitution products of the high Tc phases of Ba2RCu2O6+x, potential reaction products with different types of sample containers, and selected thin-film substrates. The International Centre for Diffraction Data/Powder Diffraction file (ICDD/PDF) coverage includes Sets 1 to 41. A cross correlation of these phases with those reported in Phase Diagrams For Ceramists (PDFC), has also been completed. Results of these efforts are tabulated.

X-Ray Powder Data for Tetracycline-urea Tetrahydrate, C23H36N4O13 and Tetracycline Hexahydrate, C22H24N2O8·6H2O

1989 ◽  
Vol 4 (3) ◽  
pp. 168-171
Author(s):  
Frank N. Blanchard ◽  
Gus J. Palenik
Keyword(s):  
Powder Diffraction ◽  
Objective Evaluation ◽  
Good Resolution ◽  
Close Correspondence ◽  
Unit Cell Parameters ◽  
Powder Diffraction File ◽  
X Ray ◽  
Cell Parameters ◽  
Low Intensity ◽  
Diffraction Patterns

AbstractIndexed powder diffraction patterns and related crystallographic data are reported for tetracycline-urea tetrahydrate and tetracycline hexahydrate, neither of which is represented in the X-ray Powder Diffraction File. Objective evaluation of the data indicates high precision of d-spacings and unit-cell parameters, intensities that are acceptably reproducible, sensitivity for low intensity reflections, good resolution of closely spaced reflections, and close correspondence with calculated patterns.

International Centre for Diffraction Data and American Society for Metals database survey of thermoelectric half-Heusler material systems

2013 ◽  
Vol 28 (1) ◽  
pp. 32-43 ◽  
Author(s):  
Winnie Wong-Ng ◽  
J. Yang
Keyword(s):  
Phase Diagrams ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Materials Selection ◽  
Powder Diffraction File ◽  
X Ray ◽  
Material Systems ◽  
Diffraction Patterns ◽  
American Society ◽  
Related Compounds

Phase diagrams and X-ray powder diffraction patterns provide critical information for thermoelectric (TE) research. We have conducted a survey of phase diagrams and powder diffraction patterns of TE systems in the ASM (American Society for Metals) Metal/Alloy database and ICDD (International Centre for Diffraction Data) PDF (Powder Diffraction File), respectively, for their availability and crystal systems. In this report, we focus on TE materials that have the half-Heusler XYZ structure, and related compounds, based on a set of materials selection rules. We found that among 306 potential XYZ compounds that we have surveyed, 234 have powder diffraction patterns in the PDF, but only 28 have phase diagram information, and 67 do not have any crystallographic information. Among the 234 phases with powder patterns, 84 were reported to have cubic F43m half-Heusler type structure, and the remainder have hexagonal, orthorhombic or other structure types. Some XYZ compounds have both cubic and hexagonal phases. This information will provide the basis for future activities for the improvement of the databases. These activities include filling the missing gaps in both phase equilibria database and the PDF, as well as adding TE and pertinent physical properties to the PDF.

Sign in / Sign up

Export Citation Format

Share Document