期刊
JOURNAL OF MATERIALS RESEARCH
卷 25, 期 11, 页码 2150-2158出版社
CAMBRIDGE UNIV PRESS
DOI: 10.1557/JMR.2010.0282
关键词
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资金
- European Union
- International Max Planck Research School for Advanced Materials
To study the crystallization kinetics of beta-Si3N4 in Si-B-C-N polymer-derived ceramics, the amorphous ceramics with composition SiC1.6N1.0B0.4 were synthesized and then isothermally annealed at 1700, 1775 and 1850 degrees C. The integrated intensities of beta-Si3N4 x-ray diffraction (XRD) patterns were used to examine the course of crystallization. The average size of the Si3N4 nanocrystallites was analyzed by means of the XRD measurements and energy-filtering transmission electron microscopy. It was realized that the nanocrystallite dimensions change insignificantly within the time period of crystallization; however, they depend significantly on the temperature. Subsequently, the kinetics of the beta-Si3N4 crystallization was analyzed. Consequently, large activation energy in the range of 11.5 eV was estimated. Moreover, continuous nucleation and diffusion-controlled growth have been concluded as the main mechanisms of the crystallization process. Further analysis points at the crucial role of the nucleation rate in the crystallization kinetics of beta-Si3N4.
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