Q11(b). Cell edge of silicon from its density
Pure silicon crystallizes in face-centred cubic diamond structure with four adjacent Si atoms at the corners of a regular tetrahedron. Calculate the unit cell length of silicon in Å. The density of pure silicon is 2.33 g/cm³ and the molar mass of silicon is 28.09 g/mol.
Answer in brief
Diamond cubic, Z = 8 atoms per cell; a = (ZM/ρNA)¹ᐟ³ = 5.43 × 10⁻⁸ cm = 5.43 Å.
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Coversdiamond cubic structuresilicon unit celldensity and cell edgeatoms per unit cellρ = ZM/NAa³
All parts of Question 11
- 11(a) Box length from the longest-wavelength transition10 marks
- 11(b) Cell edge of silicon from its density10 marks