A NEW SOLUTION ROUTE TO SILICATES .4. SUBMICRONIC ZIRCON POWDERS

Submicron-sized zircon powders have been prepared by an aqueous sol-ge l process. The starting products were zirconium oxychloride or oxynitr ate and a water-soluble silicate. The reaction took place at 120 degre es C in a PTFE-lined bomb under autogenous pressure or even at 100 deg rees C in refluxing conditions. The resulting powder has been characte rized by XRD, IR, EDAX, SEM, TEM and EXAFS. Under pseudo-hydrothermal conditions, zircon was prepared as spherical particles with a very nar row size distribution (mean size 0.6 mu m) Crystallinity was improved by thermal curing resulting, at 1100 degrees C, in disk particles (dia meter 0.35 mu m; thickness 0.13 mu m).