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 language | English (US) |
|---|---|
| Pages (from-to) | 2374-2381 |
| Number of pages | 8 |
| Journal | Journal of the American Ceramic Society |
| Volume | 74 |
| Issue number | 10 |
| DOIs | |
| State | Published - Oct 1991 |
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All Science Journal Classification (ASJC) codes
- Ceramics and Composites
- Materials Chemistry
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Epitactic Nucleation of Spinel in Aluminosilicate Gels and Its Effect on Mullite Crystallization. / Huling, Jeffrey C.; Messing, Gary L.
In: Journal of the American Ceramic Society, Vol. 74, No. 10, 10.1991, p. 2374-2381.Research output: Contribution to journal › Article
TY - JOUR
T1 - Epitactic Nucleation of Spinel in Aluminosilicate Gels and Its Effect on Mullite Crystallization
AU - Huling, Jeffrey C.
AU - Messing, Gary L.
PY - 1991/10
Y1 - 1991/10
N2 - 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.
AB - 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.
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U2 - 10.1111/j.1151-2916.1991.tb06771.x
DO - 10.1111/j.1151-2916.1991.tb06771.x
M3 - Article
AN - SCOPUS:84985133831
VL - 74
SP - 2374
EP - 2381
JO - Journal of the American Ceramic Society
JF - Journal of the American Ceramic Society
SN - 0002-7820
IS - 10
ER -