Powder Diffraction File record

The data are taken from the ICDD powder diffraction file, record No. 4-836 H.E. Swanson, E. Tatge, National Bureau of Standards (US), Circular 359, 1 (1953). 

The most complete and most often used powder diffraction database is the Powder Diffraction File (PDF), which is maintained and periodically updated by the fritemational Centre for Diffraction Data (ICDD ). PDF is a commercial database, and complete information about both the ICDD and Powder Diffraction File is available on the Web at http //www.icdd.com. This database is quite unique it contains either or both the experimentally measured and calculated digitized powder patterns for hundreds of thousands of compounds, including minerals, metals and alloys, inorganic materials, organic compounds and pharmaceuticals. The PDF is available as a whole or in subsets. Each record in the database is historically called the card."... 

Figure 4.18. Example of a record extracted from the ICDD Powder Diffraction File. ...

X-Ray Diffraction. Ash and potassium carbonate pulverized to —325 mesh were examined with a General Electric XRD-5 diffractometer. Copper radiation at 35 kvp and 16 ma was used for the analyses. Each scan was started at an angle 20 of 4° and continued through 70°. The data were recorded on a strip chart. The interplanar d spacings in angstroms for the recorded x-ray peaks were determined from a copper K (A = 1.5418 A) table, and compounds were identified from the ASTM x-ray powder diffraction file. 

X-ray diffraction patterns were obtained with a Bruker D5005 Theta-Theta diffractometer equipped with a diffracted-beam graphite monochromator using Cu Ka radiation (1.54184 A). The data were collected by continuous scanning between 15 and 73° (20) with a counting time of 8 s per 0.02°. The recorded patterns were referred to the powder diffraction file PDF-2 Database (International Centre for Diffraction Data) for the identification of phases, using the software package DiffracPlus (Socabim-Bruker). 

The simplest application of powder diffraction is to identify a crystalline phase. One merely runs the powder pattern of the solid and records either 29 values or rf-spacings or both. This information is given by the program and can be printed directly on the pattern. Then one may consult a database such as the JCPDS file. These initials refer to the JCPDS. As a result of the complexity of keeping pace with the ever growing fist of known phases, the operation grew and was renamed the International Centre for Diffraction Data (ICDD), headquartered in Newton Square, Pennsylvania. 

The powder X-ray diffraction spectra were recorded on a Philips PW 3710 diffractometer using the Cu Ka (X = 1.54178 A) radiation. The crystalline phases were identified with reference to the powder diffraction data files (JCPDS-ICDD). 

X-Ray Powder Diffraction. X-ray powder diffraction patterns were recorded with a Philips X-ray diffractometer PW1800 using the Cuk(x radiation (LFF tube, 40kV, 50 mA), a graphic back monochromator with automatic divergence slit (irradiated sample length 10 mm) and APD 1700 version 4.0 software. X-ray diffraction patterns, JCPDS files, and data from the literature were used to identify the crystallized phases obtained for randomly oriented samples. 

It is possible that the future may also see the use of digital calculators in qualitative spectrometric analyses. Various types of punched cards have been used as a method of recording spectral data on pure compounds. The purpose of these files is to facilitate the identification of spectral data on unknown substances. Their use in infrared analysis has been covered by Mecke and Schmid (M6), Keuntzel (K3), and Baker, Wright, and Opler (B2). The last named authors describe a file of 3150 spectra which was expected eventually to be expanded to include up to 10,000 spectra. Zemany (Zl) discussed the use of edge-notched cards in cataloging mass spectra and Matthews (M4) describes a similar application in connection with X-ray diffraction powder data. These two applications made use of only hand-sorting methods the files of Baker et al. were intended to be processed by machine. 

Identification of crystalline substance and crystalline phases in a specimen is achieved by comparing the specimen diffraction spectrum with spectra of known crystalline substances. X-ray diffraction data from a known substance are recorded as a powder diffractionfile (PDF). Most PDFs are obtained with CuKa radiation. Standard diffraction data have been published by the International Centre for Diffraction Data (ICDD), and they are updated and expanded from time to time. For one crystalline substance, there may be more than one file. The most recently updated file is recommended for phase identification. The early PDFs may contain errors in data obtained experimentally. More recently published PDFs are either obtained by more accurate experimental measurements or by theoretical calculation. A specimen to be identified should be in a powder form for most accurate matching. When we need to identify the crystal structure of a specimen that cannot be prepared as powder, matches of peak positions and relative intensities might be less than perfect. In this case, other information about the specimen such as chemical composition should be used to make a judgment. 

Powder X-ray diffraction patterns were recorded in a D-5000 Siemens diffractometer, using nickel-filtered CuKa as monochromatic X-ray radiation. The patterns were recorded over a range of 20angles from 20 to 70 and crystalline phases were identified using JCPDS files. 

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