Epitactic Nucleation of Spinel in Aluminosilicate Gels and Its Effect on Mullite Crystallization

Jeffrey C. Huling, Gary L. Messing

Research output: Contribution to journalArticle

146 Scopus citations

Abstract

Control over the structure of hybrid (colloidal + molecular) aluminosilicate gels was utilized to demonstrate that precursor chemistry has a direct and controllable effect on the ∼1000°C crystallization of spinel and mullite in molecular precursor systems. Synthesis or preparation conditions leading to the development of a cubic, transition alumina result in the epitactic nucleation of spinel at ∼1000°C in gels that otherwise crystallize directly to mullite at ∼1000°C. Thus, the preference for spinel nucleation in gels derived from solution precursor systems whose chemistries promote formation of transition alumina readily explains the reported inability to obtain substantial mullite yields at ∼1000°C. Isothermal transformation kinetics of colloidal and hybrid gels show that in the absence of direct mullite formation at ∼1000°C, the release of alumina from the spinel‐type crystal structure becomes the rate‐controlling step in the transformation. This necessitates higher temperatures for mullite formation and limits the kinetic enhancement possible with extrinsic increases in mullite nucleation frequency.

Original languageEnglish (US)
Pages (from-to)2374-2381
Number of pages8
JournalJournal of the American Ceramic Society
Volume74
Issue number10
DOIs
StatePublished - Oct 1991

    Fingerprint

All Science Journal Classification (ASJC) codes

  • Ceramics and Composites
  • Materials Chemistry

Cite this