Crystallization kinetics of mullite from polymeric Al2O3-SiO2 xerogels

Kiyoshi Okada, Jun Ichi Kaneda, Yoshikazu Kameshima, Atsuo Yasumori, Takahiro Takei

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49 Citations (Scopus)


The kinetics of mullite crystallization from polymeric Al2O3-SiO2 xerogels with chemical compositions of 60 and 80 mol% Al2O3 was investigated under non-isothermal conditions using DTA. The polymeric xerogels were prepared by slow hydrolysis of tetraethoxysilane and aluminum nitrate nonahydrate dissolved in ethanol. The DTA conducted at heating rates of 2, 5, 10 and 20 °C/min showed an exothermic peak at about 1000 °C associated with mullitization and/or γ-Al2O3 formation. The activation energy for the nucleation-growth mechanism of mullite, calculated by the Kissinger method, was 1202 ± 27 kJ/mol in the 60 mol% xerogel and that of mullite and γ-Al2O3 was 1092 ± 42 kJ/mol in the 80 mol% xerogels. Since these activation energies are similar to those reported for glasses, diphasic xerogels and hybrid xerogels, irrespective of their mullitization routes and temperatures, all these mullitization processes are considered to occur by a similar diffusion-controlled mechanism.

Original languageEnglish
Pages (from-to)3155-3159
Number of pages5
JournalMaterials Letters
Issue number21
Publication statusPublished - Jul 2003
Externally publishedYes


  • Activation energy
  • Crystallization
  • Mullite
  • Polymeric gel

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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