In this work, the modified Thompson-Cox-Hastings function (TCHZ) was used in the analisys of the integral breadths obtained from the broadned X ray diffraction line profiles. These set of X ray diffraction results were calculated from the "Le Bail" fitting method, which does not require any structural information, except unit cell and resolution instrumental parameters. The refinement used here is called ‘Profile Matching' in the FullProf, a program for Rietveld analysis. The method was applied in two case size-strain broadening of kaolinites from Brazilian deposits that after the treatment chemical and physical still had a content ranging between 1,55 % w/w (intermediate) to amount of 3,04% w/w (high) of structural and total iron. The Rietveld refinement was first performed by using the set of data from standard reference material LaB6to obtain all the instrumental parameters, simultaneously. This result has been used as an independent method to validate the results obtained by the ‘Profile Matching' method. It has been shown that the crystallite size decreasing and the strain increasing with Fe2O3 (% w/w) contents. The Lorentzian shape of the inherent widths of the lines diffraction is a strong indication that are the small crystallite size the main cause of the analysed kaolinites samples.
Kaolinite; X-ray diffraction; microstructural parameters
