A PROFILE-FITTING PROCEDURE FOR ANALYSIS OF BROADENED X-RAY-DIFFRACTION PEAKS .2. APPLICATION AND DISCUSSION OF THE METHODOLOGY

The convolutive X-ray peak profile-fitting methodology described in the previous paper [Enzo, Fagherazzi, Benedetti & Polizzi (1988). J. Appl. Cryst. 21, 536-542] has been applied to a series of fluorite samples milled for different times and two zirconia ultrafine powders, by using either pseudo-Voigt or Voigt (in the Kielkopf approximation) functions, in order to investigate the broadening due to microstructural factors (crystallite size and lattice distortions). In the fluorite milled powders Fourier analysis (Warren & Averbach and Vogel, Haase & Hosemann methods) has shown that lattice disorder is due to dislocations. Values for the crystallite size as well as for the lattice distortion parameters similar to those obtained with Fourier methods have been found using a suitable integral breadth plot based on an assumed Cauchyian shape for the broadened profiles. A very high computability limit was reached for the crystallite size (about 5000 A). In the ultrafine powders of zirconia the cubic, tetragonal and monoclinic polymorphs were studied. The noticeable Gaussian content present in the 222 reflections for both cubic and tetragonal forms can be explained in terms of the presence of'intercrystalline'-like distortions. This kind of lattice distortion, detected by means of the Fourier analysis, has also been confirmed by 'simplified' methods (two-line and single-line procedures). Examples of limitations of the present methodology are reported and discussed