Particle size distribution and dislocation density determined by high resolution X-ray diffraction in nanocrystalline silicon nitride powders

Gubicza, Jenő and Szépvölgyi, János and Mohai, Ilona and Zsoldos, L. and Ungár, Tamás (2000) Particle size distribution and dislocation density determined by high resolution X-ray diffraction in nanocrystalline silicon nitride powders. MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCURE AND PROCESSING, 280 (2). pp. 263-269. ISSN 0921-5093

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Abstract

Two silicon nitride powders were investigated by high resolution X-ray diffraction. The first sample was crystallized from the powder prepared by the vapour phase reaction of silicon tetrachloride and ammonia while the second was a commercial powder produced by the direct nitridation of silicon. Their particle size and dislocation density were obtained by the recently developed modified Williamson-Hall and Warren-Averbach procedures from X-ray diffraction profiles. Assuming that the particle size distribution is log-normal the size distribution function was calculated from the size parameters derived from X-ray diffraction profiles. The size distributions determined from TEM micrographs were in good correlation with the X-ray results. The area-weighted average particle size calculated from nitrogen adsorption isotherms was in good agreement with that obtained from X-rays. The powder produced by silicon nitridation has a wider size distribution with a smaller average size than the powder prepared by vapour phase reaction. The dislocation densities were found to be between about 10(14) and 10(15) m(-2).

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