Zircon formation from amorphous spherical ZrSiO4 particles obtained by hydrolysis of aerosols
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A procedure for the preparation of SiO2·ZrO2 spherical particles, based on the hydrolysis of liquid aerosols is described. A mixture of tetraethylortho-silicate (TEOS) and zirconium n-propoxide with the proper stoichiometry (Zr/Si atomic ratio = 1) was used as a liquid precursor. The alkoxide mixture had to be partially hydrolysed before aerosol generation in order to obtain solids with a zircon composition. The as-prepared powders consisted of particles in the micrometre range with an amorphous character. Energy dispersive X-ray spectroscopy (EDX), infrared (i.r.) and nuclear magnetic resonance (NMR) analyses indicated the existence of a good compositional homogeneity and a large number of Si-O-Zr bonds in the sample. Calcination of the powder up to 950°C gave rise to the segregation of silica and the crystallization of tetragonal zirconia, which transformed into the monoclinic phase after heating at 1300°C. Crystallization of zircon started on calcination at 1450°C; it was accompanied by the formation of some cristobalite. The complete transformation of the sample into zircon took place after prolonged heating (20 h) at 1500°C.
KeywordsZircon Nuclear Magnetic Resonance Cristobalite ZrSiO4 Tetragonal Zirconia
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- 9.A. Balboa, R. E. Partch and E. Matijević, Colloids Surf. 27 (1987) 123.Google Scholar
- 12.M. P. Besland, C. Guizard, N. Hounanian, A. Larbot, L. Cot, J. Sanz, I. SObrados and M. Gregorkiewitz, ibid. 113 (1991) 1982.Google Scholar
- 13.J. C. Pouxviel and J. P. Boilot, in “Ultrastructure processing of advanced ceramics”, edited by J. D. Mackenzie and D. R. Ulrich (John Wiley, New York, 1988) p. 197.Google Scholar
- 14.N. B. Colthup, L. H. Dalay and S. E. Wiberley, “Infrared and raman spectroscopy”, Academic Press, San Diego (1990) Chs 5 and 10.Google Scholar
- 16.S. Mann, C. C. Perry, R. J. P. Williams, C. A. Fyfe, C. G. Gobbi and G. J. Kennedy, J. Chem. Soc. Chem Commun. (1983) 168.Google Scholar