Polytype distribution in silicon carbide

Preparation of porous SiC ceramic with a woodlike microstructure by sol-gel and carbothermal reduction processing

“…In addition, one additional line at 2=33.82 (d=0.265 nm) in the XRD patterns of porous SiC ceramics is detected near the (111) line of the cubic structure of the silicon carbide at 2=35.64 (d 111 =0.251 nm) which is characteristic of hexagonal polytypes (a-SiC phase). 33 Diffraction peak (d 101 =0.404 nm) for crystalline SiO 2 (cristobalite) is never observed, which indicates that nearly the whole amount of silica has been consumed during carbothermal reduction reaction. The results show that the resulting porous products are essentially constituted of SiC of cubic type (b-SiC) with a minor amount of a-SiC.…”

Microstructure and thermal stabilities in various atmospheres of SiB0.5C1.5N0.5 nano-sized powders fabricated by mechanical alloying technique

“…The other two obvious distinguishable peaks for 6H-SiC are at the 34.1°a nd 38.2°, and the intensities of peaks at 34.1°and 38.2°are about the one-third of intensity of peak at 36°(PDF 29-1131). Frevel with his workers have reported a diffractogram of a 50/50 mixture of 6H-SiC and 3C-SiC (each 30 nm), and they found that the relative intensities of unambiguous reflections of 6H-SiC were very low [53]. The relative intensities at 34.1°and 38.2°were less than 20% of the intensity at 36°.…”

Dilatometric studies of (SiO2-RE2O3-Al2O3) silicon carbide ceramics

“…Silicon carbide can reveal several polymorphs [11][12] , in which the basic tetrahedron ( Figure 1) is formed with one silicon atom and four carbon atoms (or vice versa). These tetrahedrons are linked at their corners.…”