Sample broadening lattice strain

There are two major problems associated with the x-ray method. The first problem is encountered during sample preparation. At this step, preferred orientation of the particles must be minimized [1], Reduction of particle size is one of the most effective ways of minimizing preferred orientation, and this is usually achieved by grinding the sample. Grinding, however, can also disorder the crystal lattice. Moreover, decreased particle size can cause a broadening of x-ray lines, which in mm affects the values of /c and /a. The relationship between the crystallite size, t, and its x-ray line breadth, /3, (assuming no lattice strain) is given by the Scherrer equation [2] ... 

In addition, diffraction line breadth contains information on lattice strain, lattice defects, and thermal vibrations of the crystal structure. The chief problem to determine crystallite size from line breadth is the determination of /3(20) from the diffraction profile, because broadening can also be caused by the instrument. To correct for the instrumental broadening on the pattern of the sample, it is convenient to run a standard peak from a sample in which the crystallite size is large enough to eliminate all crystallite size broadening. By use of a convolu-... 

Furthermore, the presence of defects in a crystal lattice may also alter the diffraction pattern Depending on the type and the concentration of the defects, systematic peak broadening, peak shifts as well as peak splitting may be observed, and stress and strain may also influence the diffractograms [20, 21]. Thus the detailed analysis of measured peak positions, their widths and intensities can be used for the identification of the defects existing in a particular sample. 

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