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Experimental Evidence for the Anisotropic Ostwald Ripening of β‐Silicon Nitride
Author(s) -
Kitayama Mikito,
Hirao Kiyoshi,
Toriyama Motohiro,
Kanzaki Shuzo
Publication year - 1999
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.1151-2916.1999.tb02183.x
Subject(s) - ostwald ripening , materials science , anisotropy , aspect ratio (aeronautics) , silicon nitride , morphology (biology) , silicon , phase (matter) , crystallography , analytical chemistry (journal) , nanotechnology , chemistry , composite material , metallurgy , optics , chromatography , organic chemistry , physics , biology , genetics
A powder mixture of α‐Si 3 N 4 , Y 2 O 3 , and SiO 2 was heat‐treated in a loose powder state in the temperature range of 1750°–1900°C for 2 h; then, the mixture was acid‐rinsed to remove the glassy phase. The widths and lengths of the resulting β‐Si 3 N 4 crystals were analyzed quantitatively. The width–aspect‐ratio distribution of the β‐Si 3 N 4 crystals initially showed a strong negative correlation, and then the aspect ratio of crystals with small widths quickly decreased. After a stage in which aspect ratio was almost constant, regardless of the width, the width‐aspect‐ratio distribution evolved to show a positive correlation in the final stage. This pattern of morphology evolution of the β‐Si 3 N 4 crystals was in good agreement with that predicted by the anisotropic Ostwald ripening model.