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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]
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