Two sol‐gel routes have been used to prepare celsian (BaAl2Si2O8) precursors. The crystallization behaviors of unseeded gels and the gels seeded with 5 wt% feldspar, rutile, LiAISi2O2, and ZrO2 crystals as well as SrAl2Si2O8 gel have been studied using X‐ray diffraction (XRD), scanning electron microscopy (SEM), and thermal gravimetric and differential thermal analyses (TGA and DTA). It was found that metastable hexacelsian, rather than the preferred monoclinic celsian, was the major crystallization product in the two unseeded gels. Seeding largely enhanced the crystallization of monoclinic celsian, but the mechanisms involved were different for seeding with different crystals. SrAl2Si2O8 gel and ZrO2 crystals acted as normal heterogeneous centers and had little catalytic effect on monoclinic celsian crystallization. Feldspar and rutile crystals worked as epitaxial substrates for monoclinic celsian and produced pure monoclinic celsian in some temperature regions. LiAISi3O8 seeds lowered the glass transition temperature of the immediately adjacent gel matrix and led to the crystallization of pure monoclinic celsian.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of the American Ceramic Society|
|State||Published - Sep 1995|
All Science Journal Classification (ASJC) codes
- Ceramics and Composites
- Materials Chemistry