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Crystallization Mechanism of MAS‐osumilite with Composition Mg 2 Al 4 Si 11 O 30 from Glass
Author(s) -
Winter Wolfgang,
Berger Axel,
Muller Gerd,
Pannhorst Wolfgang
Publication year - 1993
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1993.tb06656.x
Subject(s) - crystallization , nucleation , materials science , quartz , phase (matter) , analytical chemistry (journal) , precipitation , crystallography , mineralogy , chemistry , metallurgy , chromatography , physics , organic chemistry , meteorology
MAS‐osumilite is a metastable double‐ring silicate which is attractive for use in glass‐ceramics because of its low thermal expansion coefficient. The phase can be crystallized from glass powders of MAS‐osumilite composition containing small amounts of BaO. The nucleation and crystallization process has been investigated by means of TEM and SEM. Crystallization starts with the precipitation of β‐quartz ss of composition MgAl 2 O 4 · n SiO 2 . BaO concentrates in a residual glass phase between the β‐quartz ss crystals. In a second stage small amounts of Ba‐osumilite (BaMg 2 Al 6 ‐Si 9 O 30 ) nucleate and crystallize from this glass phase, In a third stage BaO‐free MAS‐osumilite crystals are formed by epitactic growth on the Ba‐osumilite surfaces and grow into adjacent β‐quartz ss grains. Two factors are essential for the suppression of undesired further phases to develop a monophase (besides some Ba‐osumilite) MAS‐osumilite glassceramic: a residual glass phase with a composition close to Ba‐osumilite, and β‐quartz ss crystals having a composition close to that of MAS‐osumite.