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Figure 12
(a) The mean values of integrated intensity calculated for a 3 µm perfect crystal at 2θ = 30°, from a crystal in a random orientation, for increasing numbers of contributions. These curves give the spread in the calculated estimated mean values. As the number of contributions increases the spread in the estimated mean narrows and centres on the true mean value, but even for 50 000 contributions the reliability in measuring the mean is poor. (b) This is case for an imperfect 3 µm crystals (σ = 0.25°), where the mean is much better defined because of the suppression of the peak and increase in the dispersed intensity. (c) When the interquartile range (Q3–Q1) over the median decreases the confidence level increases and the true mean intensity becomes reliable. This plot shows that this ratio reduces with the number of crystal orientations being explored for three sizes of perfect and imperfect crystals, for 2θBn = 30°. Clearly, as the defect level increases and the crystal size reduces, fewer numbers of crystals are needed to determine a reliable intensity value.

ISSN: 2053-2733
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