Also, the ratios of the peaks are off indicating the crystallites were not sufficiently random in their orientations. The underground sample's pattern has a low signal to background ratio to the point that some of the smaller peaks detected in the well ground sample pattern disappear into the background noise. The well ground sample's diffraction pattern has a high signal to background ratio and the peak ratios match those seen in other collected diffraction patterns of this material.
The difference between the patterns is immediately obvious. The resulting diffraction patterns of the two samples are shown below. The underground sample you would be able to distinguish individual grain not only by feel but sight as well. It would resemble a flour such that if you were to rub the sample between your fingers you would not be able to feel the individual grains. The well ground sample has a particles size of at most 44 microns. The figure below illustrates this relationship for a single phase sample prepared properly, then poorly. Particle size is inversely related to both the degree of randomness of the crystallites and the measured intensity. The best way to make sure these conditions are met is to finely powder your sample.Įrrors Caused By Materials and Improper Preparation Sufficient diffraction intensity to meet satisfy counting statistics.Sufficient number of crystallites to get a representative intensity distribution for the sample.
Total randomness of crystallite orientations.Ideally, you need to achieve three conditions in order to have good data: If you do not put in the effort to properly prepare your sample you can introduce errors that make phase identification difficult to impossible and estimates of abundances and crystallinity erroneous. Proper sample preparation is essential to getting highly quality XRD data.
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