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TitleEvolution of crystalline aluminates from hybrid gel-derived precursors studied by XRD and multinuclear solid-state MAS NMR : II. Yttrium-aluminium garnet, Y3Al5O12
Publication TypeJournal Article
Year of Publication1999
AuthorsMackenzie, K.J.D., and Kemmitt T.
JournalThermochimica Acta
Pagination13 - 18
Date Published1999
ISSN00406031 (ISSN)
AbstractThe thermal evolution of structure in a hybrid gel of YAG composition (Y3Al5O12) prepared from aluminum alkoxide and yttrium acetate was studied up to 1250°C. XRD indicates that the gels are amorphous <900°C, when they abruptly crystallize to YAG and hexagonal YAlO3. The latter exists only briefly, being fully converted to YAG by 1000°C. 27Al MAS NMR shows that after the loss of volatiles at 375°C, the Al occupies three types of sites in the amorphous gel (tetrahedral, octahedral and a site characterized by an NMR resonance at 38 ppm). The distribution of Al over these sites progressively changes during heating <980°C but 89Y MAS NMR suggests that the Y is comparatively less mobile within the gel, achieving its final YAG environment only after the YAG crystal structure has been established.

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