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
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.
- 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).
- 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.