With decreased temperature, the range of the ADF narrows and the maximum peak gradually increases, http://www.selleckchem.com/products/ABT-263.html which indicates that the atomic structure becomes more orderly. To reveal the transformation of the ADF, the ADF of silicon and carbon as center atoms are analyzed in detail. Figure 4 shows the ADF of silicon and carbon as center atoms at 4500 and 100K.Figure 3The evolution of the ADF with decreased temperature.Figure 4The ADF of SiC at 4500K and 100K. ((a), (c) at 4500K and 100K, Si as central atom, CN-3, 4, 5, 6; (b), (d) at 4500K and100K, C as central atom, CN-2, 3, 4).Figures 4(a) and 4(b) show that at 4500K, complex bond types exist in liquid SiC. Silicon atoms mainly form threefold, fourfold, fivefold, and sixfold coordination structures, and fourfold silicon atoms account for the greatest proportion.
The bond angles of fourfold, fivefold, and threefold silicon atoms are distributed within the ranges of 96��C109��, ~90��, and 92��C128��, respectively. Carbon atoms mainly form threefold, fourfold, and a small number of twofold coordination structures. The bond angles of threefold and fourfold carbon atoms are distributed within the ranges of 115��C121�� and 97��C121��, respectively. Figures 4(c) and 4(d) show that silicon atoms mainly form fourfold coordination structures at 100K, and the main peak is located at ~109�� (bond angle of tetrahedral). Carbon atoms mainly form a large number of threefold coordination structures, and the main peak is located at ~120�� (bond angle of graphite).
During solidification, silicon atoms tend to form fourfold coordination structures with a tetrahedral angle, whereas carbon atoms tend to form threefold coordination structures with a graphite angle. However, no graphite structure forms at the end of solidification, as discussed in the following section.3.4. Microstructure Visualization AnalysisTo present a clear image of microstructures during solidification, Figure 5 shows a change in the main structures of silicon and carbon as the center atoms with decreased temperature. We use AmBn to denote the structure. A is the center atom type and m is the number of A. Meanwhile, B is the atom type that differs from A and n is the number of B. For example, C3Si1 represents the carbon as the center atom, and the structure comprises three carbon atoms and one silicon atom. The green ball represents carbon atom, and the purple one represents silicon atom.
Figure 5The number of main structures of C or Si as central atom with temperature decrease. ((a), (b) threefold coordination structures of C as central atom; (c), (d) fourfold coordination structures of Si as central atom).When carbon is the center atom, four kinds of threefold coordination structures exist, namely, C1Si3, C2Si2, C3Si1, and C4. Figures 5(a) and 5(b) show Brefeldin_A that the number of the four kinds of structures from more to less is C2Si2, C3Si1, C1Si3, and C4.