ABSTRACT

Laboratory synthesized (carbothermal-reduction-nitridation) 27R-SiAlON is studied in terms of crystallographic and microscopic features by detailed X-ray diffraction and electron microscopy experiments. 27R- SiAlON is analyzed to possess rhombohedral R3m structure and is best represented as Si_1.1Al_7.9O_1.9N_8.1. Lattice parameters, ion positions, bond lengths, angles as well as the crystallite size and strain have been determined for the constituent phase. The R3m phase in hexagonal setting exhibits enormous anisotropy with pseudo-tetragonality ratio c/a√6 ∼10. The electron microscopy too offers evidence of preferential growth of platelike crystals of SiAlON due to its large c-axis.

摘要

通过详细的X射线衍射和电子显微镜实验，研究了实验室合成的（碳热还原氮化）27R-SiAlON的晶体学和微观特征。分析27R-SiAlON具有菱形R3m结构，最好以Si _1.1 Al _7.9 O _1.9 N _8.1表示。已经确定了组成相的晶格参数，离子位置，键长，角度以及微晶尺寸和应变。六边形的R3m相表现出极大的各向异性，其准四方比为c /a√6〜10。电子显微镜也提供了SiAlON板状晶体由于其较大的c轴而优先生长的证据。