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Particle aggregation in alumina aerogels

Published online by Cambridge University Press:  31 January 2011

S. Keysar
Chemical Engineering Department, Technion, Haifa 32000, Israel
Y. De Hazan
Chemical Engineering Department, Technion, Haifa 32000, Israel
Y. Cohen
Chemical Engineering Department, Technion, Haifa 32000, Israel
T. Aboud
Materials Engineering Department, Technion, Haifa 32000, Israel
G. S. Grader*
Chemical Engineering Department, Technion, Haifa 32000, Israel
a)Author correspondence to this author.
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Alumina aerogels were synthesized by low temperature CO2 supercritical drying (SCD) of gels via the Yoldas process. The aerogels have a surface area of ˜425 m2/gr, similar to that obtained under high pressure/temperature SCD. The surface area and the cluster size of the aerogels are strongly influenced by the amount of acid during gelation. Gels and aerogels were studied by small angle x-rays scattering (SAXS), and the data were analyzed using the Fisher–Burford equation. The SAXS results along with TEM observations support the existence of a hierarchical aggregation at the gelation stage, having a mass fractal dimension of Dm = 2.6−2.8. During the SCD the morphology collapses to form a structure with surface fractal dimension Ds = 2.6−2.9.

Copyright © Materials Research Society 1997

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1.Fricke, J., J. Chrom. 406, 317 (1990).Google Scholar
2.Brinker, C. J. and Scherer, G. W., Sol-Gel Science: The Physics and Chemistry of Sol-Gel Processing (Academic Press, New York, 1990), pp. 408, 71, 60, 610.Google Scholar
3.Kistler, S. S., Nature (London) 127, 53 (1931).Google Scholar
4.Teichner, S. J., Nicolaon, G. A., Vicarini, M. A., and Gardes, G. E. E., Adv. Coll. Int. Sci. 5, 245 (1976).Google Scholar
5.Armor, J. N. and Carlson, E. J., J. Mater. Sci. 22, 2549 (1987).Google Scholar
6.Ayen, A. J. and Iacobucci, P. A., Chem. Eng. 5, 157 (1988).Google Scholar
7.Ponthieu, E., Grimblott, J., Elaloui, E., and Panjonk, G. M., J. Mater. Chem. 3, 287 (1993).Google Scholar
8.Mizushima, Y. and Hori, M., J. Mater. Res. 8, 2993 (1993).Google Scholar
9.Yoldas, B. E., J. Mater. Sci. 10, 1857 (1975).Google Scholar
10.Schaefer, D. W., Martin, J. E., Hurd, A. J., and Keefer, K. D., Phys. Proc. 5, 31 (1985).Google Scholar
11.Schaefer, D. W., MRS Bull. 4, 49 (1994).Google Scholar
12.Vacher, R., Woignier, T., and Pelous, J., Phys. Rev. B 37, 6500 (1988).Google Scholar
13.Chaput, F., Boilt, J. P., Dauger, A., Devreux, F., and Geyen, A., in Better Ceramics Through Chemistry IV, edited by Zelinski, B. J. J., Brinker, C. J., Clark, D. E., and Ulrich, D. R. (Mater. Res. Soc. Symp. Proc. 180, Pittsburgh, PA, 1990), p. 305.Google Scholar
14.Smith, D. M., Hua, D. W., and Earl, W. L., MRS Bull. 4, 45 (1994).Google Scholar
15.Emmerling, A. and Fricke, J., J. Non-Cryst. Solids 145, 113 (1992).Google Scholar
16.Schaefer, D. W., Shelleman, R. A., Keefer, K. D., and Martin, J. E., Physica 140a, 105 (1986).Google Scholar
17.Mizushima, Y. and Hori, M., J. Non-Cryst. Solids 167, 1 (1994).Google Scholar
18.Cabane, B., in Neutron, X-Rays and Light Scattering: Introduction to an Investigative Tool for Colloidal and Polymeric Systems, edited by Lindner, P. and Th. Zemb (Elsevier, Amsterdam, Holland, 1991), p. 247.Google Scholar
19.Martin, J. E. and Hurd, A. J., J. Appl. Crystallogr. 20, 61 (1987).Google Scholar
20.Glatter, O. and Kratky, O., Small Angle X-Ray Scattering (Academic Press, New York, 1982), p. 121.Google Scholar
21.Keysar, S., Cohen, Y., and Grader, G. S., unpublished results.Google Scholar
22.Vacher, R., Woignier, R., and Pelous, J., Phys. Rev. B 37, 6500 (1988).Google Scholar
23.Campaniello, J., Berthet, P., d'Yvoire, F., and Revcolevschi, A., J. Mater. Res. 10, 297 (1995).Google Scholar
24.Freltoft, T., Kjems, J. K., and Sinha, S. K., Phys. Rev. B 33, 269 (1986).Google Scholar
25.Bale, H. D. and Schmidt, P. W., Phys. Rev. Lett. 53, 596 (1984).Google Scholar
26.Singhal, A. and Keefer, K. D., J. Mater. Sci. 9, 1973 (1994).Google Scholar
27.Zarzycki, J., J. Non-Cryst. Solids 95&96, 173 (1987).Google Scholar