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RESEARCH PRODUCT

Structural Evolution and Vanadium Distribution in the Preparation of V4+-ZrSiO4 Solid Solutions from Gels

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Vanadium-containing ZrSiO4-gel precursors with nominal compositions Vx-ZrSiO4 with x= 0.0, 0.002, 0.004, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.1, and 0.2 were prepared using a previously reported procedure and thermally treated over a range of temperature up to the formation of the V4+-ZrSiO4 solid solution. The structural evolution and the V4+ location and its homogenous distribution were followed using powder X-ray diffractometry and electron spin resonance spectroscopy (ESR). Our experiments showed that a tetragonal form of V4+-ZrO2 was the first crystalline phase obtained on heating the gels. On further heating, a phase transformation to the monoclinic form of V4+-ZrO2 took place. Finally, the monoclinic form reacted with amorphous SiO2 to form the V4+-ZrSiO4 solid solution. A semiquantitative determination of the vanadium solubility in the ZrSiO4 phase using ESR confirmed previously reported results obtained by lattice parameter variation over the solid-solution series.