Question

single crystal Si (100) has a cubic unit cell, with a size of 5.43 A (you can look it up at here). However, the d-spacing between parallel planes for Si crystal is only ¼ of it (the reason for this is shown in the picture on right.) Therefore, the strongest reflection of (100) Si is between the yellow planes (400).

(b) If one uses a Cu Kalpha X-ray source with a wavelength 1.54 A, what would be location of a peak of X-ray signal? If one uses a Co Kalpha X-ray source with a wavelength 1.79 A, what would be the location of the peak?

(c) Please go to google, and search for an image (spectrum) of Silicon X-ray diffraction. Please note the spectrum typically plots between X-ray signal versus 2q (not q ). Please paste this image to the homework and use the peak in this image to estimate the wavelength of the X-ray source used for that spectrum.

Space group: Fd-3m

Space group number: 227

Structure: diamond

Cell parameters:

a: 543.09 pm

b: 543.09 pm

c: 543.09 pm

α: 90.000°

β: 90.000°

γ: 90.000°