Multi-analytical study of syntactic coalescence of polytypes in a 6H–SiC sample

Non-Destructive In Situ Study of Plastic Deformations in Diamonds: X-ray Diffraction Topography and µFTIR Mapping of Two Super Deep Diamond Crystals from São Luiz (Juina, Brazil)

“…According to the XRDT data, diamond BZ270 consists of an aggregate of slightly misoriented grains (G) that are not visible simultaneously at the individual angular settings due to the different diffraction vector (Figure 2 In the topographs of Figure 2c,d, the diffraction contrast corresponding to two slightly different angular settings of the same diffraction vector (g = [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] shows that the diamond region containing the ferro-periclase inclusions is really a grain (G) that is differently oriented with respect to the other diamond regions. In the Figure 2c G is out of contrast, whereas in Figure 2d G is in diffraction contrast and the surrounding grains are out of contrast.…”

Polytype inclusions and polytype stability in silicon-carbide crystals

“…Inclusions of the 15R polytype can arise even at the "seed-growing ingot" boundary [2] and disappear at the moment of conclusion of the growth process [49]. It was noted by Basceri et al [50] that the appearance of 15R inclusions in a 6H ingot conventionally takes place in azimuthal directions 〈11 0〉 at the growth surface.…”

“…A similar effect is provided by the use of a seed with a slight deviation from the (0001) plane with a high reticular density (so-called off-cut (0001) seeds, typically, with a deviation angle of 4° or 8° in the direction of the azimuth [11 0]). At the same time, off-cut angles that are too large lead to the formation of macrosteps and the local supersaturation change, which results in breakdown of the growing polytype and the appearance of polytype inclusions [2].…”

“…The causes of the appearance of parasitic polytype inclusions are not quite clear, although it is evident from first principles that different polytypes of silicon carbide are bound to feature similar conditions of crystallization. As a rule, the crystallographic axes of intergrowing polytypes in the hexagonal composition are parallel and syntactic coalescence of competing polytypes is observed [2].…”

SiC, from Amorphous to Nanosized Materials, the Exemple of SiC Fibres Issued of Polymer Precursors

“…This often gives rise to more or less lamellar compounds with stacking faults along one direction: carbides (Feldmann et al, 1968;Salvador & Sherman, 1991;Choyke & Pensl, 1997), sulfides (CdS, ZnS, TiS 2 , ... (Kaflawi et al, 1969;Schneide & Kirby, 1972;Tronc et al, 1975;Moret & Huber, 1976;Lincot et al, 1997;Agrosi et al, 2009;Alvarez-Garcia et al, 2009;Chi et al, 2011), nitrides (Komatsu et al, 2010) but also some oxides (e.g. BaTiO 3 perovskites (Wu et al, 2006;idem, 2009)) and even diamond (Fayette et al, 1995;Bhargava et al, 1995).…”