Crystallization of Nanocomposite Glasses Made by the SSG Process
Abstract
The two main objectives of this research were: (a) to crystallize nanocomposite glasses through solid-state epitaxy and (b) to demonstrate the critical role of epitaxy in crystallization by fabricating sol-gel films on single crystal substrates of a particular orientation. During the last three years we have been able to achieve both these goals using several compositional systems. We have been able to crystallize through seeding albite (NaAlSi3O8) glass which has been considered to be impossible to crystallize. Orthoclase (KAISi3O8) which is extremely difficult to crystallize has also been crystallized using a compositionally multiphasic gel and crystalline seeds of KA1Si3O8, NaAlSi3O8, CaAl2Si2O8 and SrAl2Si2O8 feldspars. Monoclinic BaAl2Si2O8 has been crystallized at significantly lower temperatures by seeding with monoclinic BaAl2Si2O8 or SrAl2Si2O8 seeds. The effect of seeding has been minor or could not be detected in other glass systems such as Li2O-Al203-SiO2, Rb2O- Al2O3-SiO2 and Cs2O-Al203-SiO2. Little or no effect of seeding was found in non- oxide glasses such as silicon oxycarbide glasses. The role of epitaxy in crystallization has been demonstrated convincingly by making dense, epitaxial SrTiO3 and TiO2 thin films on single crystals of SrTiO3 and TiO2 of a particular orientation. The nanocomposite approach which has been discovered and developed through AFOSR support to us is now a well established practice the world over.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 12, 1993
- Accession Number
- ADA262892
Entities
People
- Rustum Roy
- Sridhar Komarneni
Organizations
- Pennsylvania State University