Formation of β-Silicon Nitride Crystals from (Si,Al,Mg,Y)(O,N) Liquid: I, Phase, Composition, and Shape Evolutions

Autor:	Tseng-Ying Tien, Ling-Ling Wang, I-Wei Chen
Rok vydání:	2003
Předmět:	Crystal Sialon chemistry.chemical_compound Supersaturation Crystallography Silicon nitride chemistry Precipitation (chemistry) Materials Chemistry Ceramics and Composites Nucleation Crystal growth Nitride
Zdroj:	Journal of the American Ceramic Society. 86:1578-1585
ISSN:	1551-2916 0002-7820
DOI:	10.1111/j.1151-2916.2003.tb03517.x
Popis:	Precipitation, growth, and coarsening of Si3N4 crystals in (Si,Al,Mg,Y)(O,N) liquids at 1680°C has been studied. The initial nucleation of β-Si3N4 occurs mostly on α-Si3N4 because of the very high supersaturation of the liquid. After a brief period of growth, the crystals then undergo accelerated coarsening, decreasing the crystal concentration by almost 100 times with little change in the total crystal volume. Meanwhile, the crystals gradually transform from β-Si3N4, by substituting Si-N with Al-O, to β′-SiAlON of various compositions. The evolution of aspect ratio strongly depends on the Si/(Al,Mg,Y) ratio, which is rationalized by cation segregation to the interface driven by the acidity-basicity differential between the liquid and the crystal.
Databáze:	OpenAIRE
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