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Particle aggregation in alumina aerogels

  • S. Keysar (a1), Y. De Hazan (a1), Y. Cohen (a1), T. Aboud (a2) and G. S. Grader (a1)...

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.

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Journal of Materials Research
  • ISSN: 0884-2914
  • EISSN: 2044-5326
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