Celsian formation in Si3N4–Ba0.75Sr0.25Si2Al2O8 composites

The formation of monoclinic celsian in Ba0.75Sr0.25Al2Si2O8 (BSAS) sol–gel glass powder and in 50 wt.% Si3N4 particle-reinforced BSAS composites fabricated by a low-temperature hot pressing was investigated. Results indicated that celsian formation depended on the polymorphs of the Si3N4. Hexacelsian to celsian transformation was impeded when the α- to β-Si3N4 phase transformation occurred.