Hydrothermal synthesis of porous zircon in basic fluorinated medium

The hydrothermal synthesis of zircon was performed under autogenous pressure, from inorganic precursors in aqueous fluorinated basic medium. The powders obtained were characterized by an abnormal broadness of all XRD peaks except for the (200) and (220) peaks. Their morphology was strongly dependent upon the concentration [F-] of fluoride ions in the synthesis gel. At high [F-], ellipsoidal agglomerates were produced; the powders exhibited a specific surface area of about 200 m(2) g(-1); the frame of the agglomerates was not destroyed by annealing at 800 degrees C for 72 h, and 50% of the surface area was maintained. At low [F-], layered platelets were formed. (C) 1999 Elsevier Science B.V. All rights reserved.