Structural change of kaolinite and pyrophyllite induced by dry grinding.

The structural analysis of ground kaolinite and pyrophyllite prepared by dry grinding with the different periods has been made by determining the radial distribution functions from X-ray diffraction data. The SiO4 tetrahedra remain unchanged in either sample of ground kaolinite and pyrophyllite. Whereas, the increment of grinding time has been found to induce the decrease of oxygen coordination number and the corresponding interatomic distance around aluminum.