STRUCTURAL DEFECTS AND ACIDIC AND BASIC SITES IN SOL-GEL MGO

MgO prepared with the sol-gel technique had crystalline structure defe cts, obtained from X-ray powder diffraction and crystalline structure refinement, that correlated with its acidic and basic sites, The acidi c sites, measured by adsorbing pyridine and NH3, were found when bruci te and MgO coexisted, which only occurred after annealing the sample a t 673 K, Two different basic sites, measured by adsorbing CO2, were pr esent in a total concentration of about 10(21) sites per gram. These s ites correlated to the presence of magnesium vacancies in MgO crystal. Both basic site and magnesium vacancy concentrations diminished when the sample annealing temperature was increased.