Clay Mineralogy and Geochemistry Exercise

1. Collect an X-ray diffraction pattern for the National Institute of Standards and Technology (NIST) - Standard Reference Material SRM675-fluorophlogopite,  SRM640b silicon, or SRM1976b (provided). Use the following scan parameters:

Start: 3 2θ
End : 75 2θ

Step increment: 0.02 2θ

Note the divergent slit used (use 0.6 mm).  Feel free to change to larger or smaller slit to see what happens.

2. Determine the positions of the peak maxima after Kα2 stripping and background correction. Report experimental positions in both 2θ and . (i.e., print a peak table). Make a full scale plot of your diffraction data.

3. Compare the observed values of the peak positions with those provided on the reference certificate for SRM675 or SRM640b or SRM1976b (remember we use CoKα radiation: λ = 1.789 ).  You may need to convert values to d-spacings.

4. Make a plot of the reference positions versus the observed positions (use 2θ space... i.e. not ).

Now ask yourself... How much instrument error should be expected for these given scan parameters?