Concept information
Preferred term
XRPD
Definition
- An x-ray powder diffractometer is primarily used for the identification of phases in powder form. An x-ray beam of known wavelength is focused on a powdered sample and x-ray diffraction peaks are measured using a germanium detector; the d-spacing of the observed diffraction peaks is calculated using Bragg's Law [n*lamda = 2dsin(theta)]. The Scintag Pad V automated powder diffractometer uses a Cu x-ray tube with variable filters, a four-sample changer, and a low-noise, high efficiency, liquid-nitrogen cooled germanium detector. The goniometer is automated and software packages are run from a PC running Windows NT 4. A number of Scintag software packages are available for routine powder diffraction data acquisition, background correction and peak identification. Unknowns can be matched to JCPDS cards in an on-line database. Other software is available for quantitative analysis of powder mixtures, unit cell refinement, Rietveld analysis, and GSAS structural analysis. Samples sho uld be prepared as powders with a grain size of 10 um (approximately), and typically about 100 milligrams of sample is required. Additional information available at "http://www.gps.caltech.edu/facilities/analytical/xrd.html" [Summary provided by Caltech] (en)
Broader concept
URI
https://gcmd.earthdata.nasa.gov/kms/concept/f54aafd2-925e-4653-b897-c6ae4e094c69
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