Nature of mechanically induced defects in polycrystalline hydrargillite and Al2O3-A1(OH)3 studied by radiation methods

Mechanical treatment of hydrargillite Al(OH)3 in a vibrational grinder and in a ball-mill grinder increases the dispersion, the specific surface area, and the unit-cell constants. An x-ray amorphous phase forms. Differences in the nature and in the concentration of paramagnetic centers arise on γirradiation (77 K) of the mechanically treated samples. Anion vacancies and oxygen ions with disrupted short-range order appear in the mechanically treated samples. Their concentration increases with increased time of mechanical treatment. Pulsed thermal treatment of hydrargillite forms the Al2O3-Al(OH)3 system and anneals the mechanically induced defects.