1. The ball and stick model shows the stacking of the a-b planes of SiC along th
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Question
1. The ball and stick model shows the stacking of the a-b planes of SiC along the vertical direction and the dotted lines depict the unit cell stacking. (a) What is the hybridization of C and Si, and how many bonds each makes in the structure. (b) Identify the stacking sequence of the atomic planes in terms A,B,C etc. (c) How many layers per unit cell? (d) What is the name of the structure if the stacking were to be ABABAB? (2H, 4H) (e) Identify the crystallographic direction along the direction of stacking . The ball and stick model shows the stacking sequence for cubic sic (a) Identify the stacking sequence of the atomic planes in terms of A,B,C etc. (b) How many (Si-C) layers are there per unit cell? c) Identify the crystallographic direction along the direction of stacking: 3. Determine the M,Ny stoichiometries of the following edge shared and corner shared octahedral arrangements (the center positions are occupied by M and the vertices are occupied by N atoms)Explanation / Answer
1. a) The concept of mixing atomic orbitals of Silicon and Carbon to form hybrid orbitals (which have different shapes, energies etc than the original Si and C) is known as hybridization of Silicon (Si) and Carbon (C).
2. a) The stacking sequence of the atomic planes, in this case, is- ABAB.
This is the model for 2 hexagonal SiC. Thus, the sequence will be ABAB.
b) There are two (SiC) layers per unit cell.
The ball and stick model shown in the picture is of 2H-SiC. The "2" in 2H-SiC model denotes the number of double atomic layers in one repeating unit; ie, unit cell.
c) The stacking direction is tetrahedral and the stacking done is horizontal.
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