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Methods, Problems and Solutions

Calibration standards for Powder Diffraction

Silver Behenate as a low to medium angle calibration standard for powder diffraction

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Refer Also: [Powder Data Conversion Software] | [Powder Data Visualisation] | [Peak Find/Profiling Software] | [Indexing Software] | [Unit Cell Refinement Software] | [Structure Conversion]

Additions/Corrections/Changes Welcome

The problem and possible solution

Calibration is necessary for PSD (Position Sensitive Detectors) based instruments to relate channel number to two-theta angle. This is especially so with INEL PSDs where there can be discontinuities not modellable via normal polynomial fitting. (instead use a spline curve fit where the curve has to go through each calibration point).

Hoever a common problem is that most standards do not have many peaks at low angle.

Thus Silver Behenate (c-axis= 58.373 to 58.380 Anstrom) for low to medium angle calibration; combined with an appropriate medium to high angle standard (such as Cubic Y2O3 (IA3 a=b=c=~10.6 Angstrom) - annealed at 1200C for a few days) may offer a solution covering the entire angular range.

The following is based around the following publications and data:

  • T.N. Blanton, T.C. Huang, H. Toraya, C.R. Hubbard, S.B. Robie, D. Louer, H.E. Gobel, G. Will, R. Gilles and T. Raftery, "JCPDS - International Centre for Diffraction Data round robin study of silver behenate. A possible low-angle X-ray diffraction calibration standard", Powder Diffraction, (1995), Vol 10, pp 91-95

  • T.N. Blanton, C.L. Barnes and M. Lelental, "Preparation of silver behenate coatings to provide low- to mid-angle diffraction calibration", J. Appl Cryst, (2000), 33, pp 172-173.

  • The data used in the following tutorials was collected by Tom Blanton at Kodak. From Tom Blanton (E-mail: thomas.blanton@kodak.com): "The radiation is CuKalpha, Bragg Brentano diffractometer, AgBehenate coated on a (510) Silicon wafer, 0.02 deg/step, 4sec/step. Data have not been corrected for any sample displacement."

  • Instrument setting used for collecting the data:

    • Rigaku Ultrax generator, diffractometer
    • Copper rotating anode
    • Normal Focus 0.5mm x 10mm
    • Bragg-Brentano Diffractometer 185mm radius
    • Sample analyzed in reflection mode geometry
    • 0.5mm divergence slit, soller slit, sample, 0.5mm scatter slit, soller slit, 0.3mm receiving slit, diffracted beam curved graphite monochromator(tuned to CuKalpha), 0.6mm detector slit, scintillation detector


Obtaining Silver Behenate

Quoting from Blanton, et al (2000), "Eastman Kodak Company provided silver behenate to The Gem Dugout (Smith. 1999). from where it may be purchased for scientific study. One-half of the purchase price is donated to the International Centre for Diffraction Data for the ICDD Crystallographic Scholarship fund.]"

Smith, D.K. (1999). The Gen Dugout. 1652 Princeton Drive, State College, Pennsylvania, 16803, USA. E-mail: smithdeane@aol.com


Other Available NIST/NBS XRD Standards


Data and Tutorial Run Throughs



Refer Also: [Powder Data Conversion Software] | [Powder Data Visualisation] | [Peak Find/Profiling Software] | [Indexing Software] | [Unit Cell Refinement Software] | [Structure Conversion]

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