These templates were created by Gary Novak and Alan Colville, 1989, American Mineralogist, v. 74, p. 488-490.
These templates are a set of Excel spreadsheet programs that calculate unit cell parameters from X-ray diffraction data using a least squares fit procedure. The programs require 2-theta peak positions and your assigned {hkl} indexes for those peaks. There is one template for each of the six crystal systems (hexagonal and trigonal use the same template).
- The templates were developed using the Excel spreadsheet programming language.
- OPEN the template for the crystal system of interest to you.
- Copy the first yellow row (light and dark yellow) down into exactly as many rows as you have indexed peaks ({hkl} values from the book or CD Power Diffraction File indexes).
- Replace the example 2-theta and miller index {hkl} values with your own. Enter Miller indices with negative intercepts as negative numbers.
- For hexagonal and trigonal minerals, the formal Miller indices usually take the form {hkil}, as compared to {hkl} for the other crystal systems. Because h + k + i = 0, i is not necessary so only h, k, and l are listed in the Power Diffraction File indexes.
- The best fit (refined) unit cell parameters are located in the blue area at the bottom of the spreadsheet.
- You MUST check your work. The observed and calculated d spacings should be similar, and the delta-d column values should generally be <0.005. Axial lengths should generally be within 0.02 Å of the book values. If your delta-d and axial length accuracy is worse, carefully check the 2-theta angles you entered and your Miller index assignments.
Advanced notes
- Change the Alpha and Alpha 1 X-ray wavelengths if you are using a tube other than cobalt.
- Set the 2-theta Correction if the 2-theta values are systematically incorrect by a known amount.
- If you are not using Ka1-stripped 2-theta values, set the Ka/Ka1 cut-over value to 50° 2-theta.
Cell refinement templates:
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