Crystallization behaviour and microstructural development in ZrSiO4 and V-ZrSiO4 solid solutions from colloidal gels

Zircon and vanadium-doped zircon blue pigments were prepared by heat treatm ent of gel precursors. Gels with nominal compositions V-x-ZrSiO4 with x = 0 .0, 0.002, 0.004, 0.02 and 0.2 were prepared by formation of a silica coati ng on zirconia colloidal particles previously obtained. The crystallization behavior and microstructural evolution were studied using X-ray powder dif fraction (XRD), energy dispersive X-rays microanalysis (EDX), field emissio n scanning electron microscopy (FESEM), transmission electron microscopy (T EM) and selected area electron diffraction (SAED). The results indicated th at the vanadia loading in the precursor gels speeds up the crystallization of the vanadium-containing tetragonal zirconia solid solutions and their tr ansformation to the monoclinic form. The overall conversion rate of gel pre cursors to pigmenting powders increased when the vanadia content was higher . Microstructural data revealed that the used procedure for the preparation of vanadium-zircon pigments allowed high-purity acid non-agglomerated powd ers with controlled particle size to be obtained. (C) 2000 Elsevier Science Ltd. All rights reserved.