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 (provided). Use the following scan parameters:
Start: 5° 2-theta
End : 55° 2-theta
Chopper increment: 0.01° 2-theta
2. Determine the positions of the peak maxima using the graphics program (see users guide in lab). Report positions in both 2-theta and Å… (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 (remember we use CoKα radiation: l = 1.79021 Å)
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4. Make a plot of the reference positions versus the observed positions. Fit each data set (1°/min and 5°/min) with a linear regression and give the slope, intercept and the correlation coefficient. Now ask yourself... How much instrument error should be expected for these given scan parameters?