Crystallization kinetics of Si 3 N 4 in Si–B–C–N polymer-derived ceramics

• Published in: Journal of materials research 2010-11, Vol.25 (11), p.2150-2158
• Main Authors: Tavakoli, Amir H., Gerstel, Peter, Golczewski, Jerzy A., Bill, Joachim
• Format: Article
• Language: English
• ISSN: 0884-2914; 2044-5326
• DOI: 10.1557/jmr.2010.0282

To study the crystallization kinetics of β-Si 3 N 4 in Si–B–C–N polymer-derived ceramics, the amorphous ceramics with composition SiC 1.6 N 1.0 B 0.4 were synthesized and then isothermally annealed at 1700, 1775 and 1850 °C. The integrated intensities of β-Si 3 N 4 x-ray diffraction (XRD) patterns were used to examine the course of crystallization. The average size of the Si 3 N 4 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 β-Si 3 N 4 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 β-Si 3 N 4 .