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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

Unit Cell refinement and HKL assignment of silver behenate using Celref for Windows

The CCP14 Homepage is at http://www.ccp14.ac.uk

[Back to Problems and Solutions] | Back to: [Back to Powder Calibration Standards Homepage]

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

In this run through, we will profile the Silver Behenate peaks using XFIT ready for unit cell refinement and/or inserting into a calibration program.

Celref for Windows can be obtained via the Celref/LMGP Suite tutorials homepage.


Obtaining example Silver Behenate data


  • Run Celref, Load the raw data file, and in the measured reflections option area, open the XFIT peak profiling file determined in the previous tutorial runthrough (1.54056 Angstrom is the wavelength).


  • In the initial cell parameters option area, select keyboard and input a=0.1, b=0.1, c=58.380 (or the certificate value provided with the sample).

    Select the Orthorhombic Cell and P222 spacegroup. Putting the a and b to very low values means in effect that only the 0 0 l reflections are calculated.

  • Then press the Calc button.


  • Under Selection of the reflections option area, select Automatic Selection

  • Under Cell refinement de-select a and b to be refined (only refine on the c-axis). (If the c axis value has been predetermined (or a certificate value provided), refine nothing as all the relevant information is provided in the left hand dialog boxes)


  • Select the Refine button to perform the Unit cell refinement.

  • Calculated and observed two-thetas, d-spacings and HKL's will be outputted allowing you to use this information for calibration purposes.


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

[Back to Problems and Solutions] | Back to: [Back to Powder Calibration Standards Homepage]

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