THE ENCAPSULATING EFFICIENCY FOR VANADIUM OF ZRO2.SIO2 GELS PREPARED FROM ALKOXIDES TO GIVE V-ZRSIO4 BLUE COLORED STAINS

It is possible to attain a blue coloured stain in the V2O5.ZrO2.SiO2 s ystem stable at 1200-degrees-C. However, it is necessary to operate at a low content Of V2O5, lower than 0.03 mol/mol of zircon, and by a so l-gel method. Otherwise, the sample turns to a green colour when fired above 800-degrees-C. In this paper, a mechanism of reaction for the b lue stain is suggested based on XRD and SEM-EDX data. The vanadium enc apsulation efficiency of both colloidal and polymeric gel routes is ev aluated. The effect of a catalyst under the stains obtained from gels prepared by polymerisation-condensation of a mixture of alkoxides (pol ymeric gels) is also studied.