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| Titel |
X-ray microdiffraction as a tool for quantitative phase analysis |
| VerfasserIn |
L. Medici, C. Belviso, S. Fiore |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250028132
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| Zusammenfassung |
| This work aims to verify if data obtained via laboratory-based X-ray microdiffraction are
suitable for mineralogical quantitative analyses and to determine the best instrumental
parameters for quantitative phase analyses using powder diffraction.
A X-ray microdiffractometer needs few milligrams of powder material to obtain a
complete X-ray spectrum and can directly work on thin sections and bulk matrices; this
routine technique could satisfy the claims of a lot of experiments where small samples are
used and mineralogical quantitative determinations are required.
Different ratios of solid binary mixtures of quartz, calcite, kaolinite, and illite were
prepared by analytical balance: 5/95, 25/75, 50/50, 75/25, 95/5. These powder mixtures were
analyzed using a Rigaku Rint 2200 instrument with a conventional Bragg-Brentano geometry
equipped with a copper tube and a graphite crystal monochromator. The data were collected
in the angular range 3-100Ë 2θ with steps of 0.02Ë and 5 s/step. The data collections were
converted into GSAS files for EXPGUI software and quantitatively refined by Rietveld
method. These refinements and weight amounts were used as references for the following
data collections.
The same powder mixtures were analyzed by a X-ray microdiffractometer Rigaku D-Max
Rapid, equipped with an image plate detector, a flat graphite monochromator, a microscope
for the positioning of the sample in the path of the X-ray beam, operating at 40 kV and 30
mA with CuKα radiation. Each powder sample was collected with different beam collimators
(beam diameters: 0.03, 0.05, 0.10, 0.30 mm), different collection times, two fixed values of
omega angle (3Ë and 6Ë ), five angular ranges of rotation of phi angle (0Ë , 30Ë , 90Ë
, 180Ë , 360Ë ). The XRD data were collected as two-dimensional images and
converted into 2θ - I profiles; further conversions into GSAS files for EXPGUI
software were carried out, and the data were quantitatively refined by Rietveld
method.
The results of these refinements were compared with the weight amounts and the results
obtained by the other X-ray technique, highlighting X-ray microdiffraction appears to be
suitable for mineralogical quantitative analyses using different instrumental parameters. |
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