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RESEARCH PRODUCT

The stoichiometry of blue vanadium doped zircon obtained by sol-gel methods

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Abstract In this study, Sol-Gel processes in aqueous solution were used to investigate the stoichiometry of the V/1bZrSiO 4 solid solutions achieved by this method. Compositions with a formal stoichiometric defect in: (a) ZrO 2 ([ZrO 2 ] 1−2x [SiO 2 ] [V 2 O 5 ] x ), and (b) in SiO 2 ([ZrO 2 ] [SiO 2 ] 1−2x [V 2 O 5 ] x ), x=0.02, 0.04, 0.05 and 0.10 have been prepared. X Ray Diffraction analyses in fired samples (1200°/3 days) showed that cristobalite and monoclinic zirconia appear as residual crystalline phase in (a) and (b) compositions respectively, except in sample (a) with x=0.02 in which no residual phase was detected and therefore is considered stoichiometric. This sample and sample (b) with x=0.02, becomes blue and the others green. X Ray Fluorescence analyses carried out in the samples indicate a stoichiometry V 0.004 Zr 0.996 SiO 4 for blue sample. Similarly, amounts of vanadium of 0.02 and 0.03 per mol of zircon were measured in green sample (a) with x=0.05 and in a commercial blue turquoise, obtained adding 0.20 mols of NaF to it and treated by a conventional ceramic method, respectively.