X-ray powder

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X-ray powder diffractometer
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X-ray powder diffractometer
radiation counter
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X-ray powder diffractometer
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Powder diffractometer (see Jenkins Snyder,
chap. 7)

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Powder diffractometer (see Jenkins Snyder,
chap. 7)
Bragg-Brentano geometry
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X-ray powder diffractometer
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X-ray powder diffractometer
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X-ray powder diffractometer
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X-ray powder diffractometer
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X-ray powder diffractometer
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X-ray powder diffractometer
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X-ray powder diffractometer
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X-ray powder diffractometer
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X-ray powder diffractometer
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X-ray powder diffractometer
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X-ray powder diffractometer
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X-ray powder diffractometer
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X-ray powder diffractometer
To maintain the focusing geometry, when counter
is rotated at rate of 2?/min, specimen is also
rotated at rate of ?/min
??/min
?/min
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Powder diffractometer
Bragg-Brentano instrument - errors (see Klug
Alexander) Axial divergence - axis, here, is
main rotation axis - asymmetric broadening
toward low 2? - negative 2? error up to 90
- positive 2? error beyond 90
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Powder diffractometer
Bragg-Brentano instrument - errors (see Klug
Alexander) Axial divergence - axis, here, is
main rotation axis
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Powder diffractometer
Bragg-Brentano instrument - errors (see Klug
Alexander) Axial divergence - axis, here is
main rotation axis each section of Soller
slit produces its own Debye ring from a
specific region in the specimen divergence
angle typically 2.5
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Powder diffractometer
Bragg-Brentano instrument - errors (see Klug
Alexander) Axial divergence - axis, here is
main rotation axis each section of Soller
slit produces its own Debye ring from a
specific region in the specimen divergence
angle typically 2.5
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Powder diffractometer
Bragg-Brentano instrument - errors (see Klug
Alexander) Flat specimen peak shifts to
lower 2? asymmetric broadening depends on
beam divergence 2?, plus specimen shape
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Powder diffractometer
Bragg-Brentano instrument - errors (see Klug
Alexander) Specimen transparency
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Powder diffractometer
Bragg-Brentano instrument - errors (see Klug
Alexander) Specimen displacement Usually
largest error in expt'l data Neg. peak shift -
0.01 2?/15??displacement Asymmetric
broadening toward lower 2?
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Powder diffractometer
Bragg-Brentano instrument Divergence slit
choice
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Powder diffractometer
Bragg-Brentano instrument Divergence slit
choice Or, theta-compensating slit -
divergence slit opens as theta increases
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Powder diffractometer
Bragg-Brentano instrument Receiving slit
choice
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Powder diffractometer
Bragg-Brentano instrument Receiving slit
choice lowers intensity - little
improvement in resolution poor
resolution - little improvement in
intensity
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Powder diffractometer
Bragg-Brentano instrument Receiving slit
choice correct slit size
0.15
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Powder diffractometer
Alignment steps
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Powder diffractometer
Alignment steps Align to focal spot Set
take-off angle
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Powder diffractometer
Alignment steps Align to focal spot Set
take-off angle Zero alignment 21
alignment
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Powder diffractometer
Alignment steps Align to focal spot Set
take-off angle Zero alignment 21
alignment
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Powder diffractometer
Alignment steps Align to focal spot Set
take-off angle Zero alignment 21
alignment
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Powder diffractometer
Alignment checks Run calibration pattern - use
suitable standard NIST 640c (Si)
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Powder diffractometer
Alignment checks Run calibration pattern - use
suitable standard
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Powder diffractometer
Alignment checks Run calibration pattern - use
suitable standard Watch for Intensity
loss Angle shifts Resolution loss
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Powder diffractometer
Alignment checks
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Powder diffractometer
Alignment check "Five fingers of
quartz"
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Powder diffractometer
Alignment check "Five fingers of
quartz" Measure position intensity of
(203)?1 H1/H2
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Powder diffractometer
Alignment checks Run calibration pattern - use
suitable standard NIST 1976 (Al2O3)
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Powder diffractometer
Alignment checks Run calibration pattern - use
suitable standard
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Powder diffractometer
Alignment checks Run calibration pattern - use
suitable standard