THE EFFECT OF THE CALCINATION PROCESS ON THE CRYSTALLITE SHAPE OF SOL-GEL CERIUM OXIDE USED FOR GLASS POLISHING

Pure cerium oxide was produced via the sol-gel process, which allowed an investigation into the effect of thermal heat treatment on its crys tallite shape and size. Transmission electron microscopy (TEM) and X-r ay diffraction studies demonstrated that the actual crystallite shape changed with increasing calcination temperature. At a temperature of 8 50 degrees C, truncated octahedral crystallites were produced which di splay a greater a rea of close packed planes of cerium atoms on the su rface, compared to those calcined at lower temperatures. Cerium oxide th at had undergone calcination at 850 degrees C is a Iso very effecti ve as a glass-polishing medium. Because the calcination process effect s both the shape of the crystal and its size at this temperature, it i s proposed that polishing efficiency is predominantly determined by th e higher incidence of cerium atoms th at can be presented to the glass surface.