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I have a query as to how interplanar spacing in fcc and bcc can be determined. In line with the known formula,

$$d_{hkl} = \frac{a}{\sqrt{h^2+k^2+l^2}}$$

for a crystal with Miller indices (1 1 0), if the crystal is scc/bcc then the formula holds good! But for fcc, it does not! According to the formula, the spacing is $\frac{a}{\sqrt{2}}$, but in practical observation it is $\frac{a}{2\sqrt{2}}$.

I searched for a distinct formula on the internet to satisfy the fcc case, but I failed! I read some books, looked at some questions, and the author uses the ordinary formula to solve the questions.

I'm confused! Help me to understand where I'm incorrect!

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That's the spacing for (2,2,0) and not (110). For an FCC crystal with identical atoms the (110) has zero structure factor and does not show up.

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  • $\begingroup$ Can you explain the second part more clearly ? $\endgroup$
    – Prathamesh
    Sep 8, 2019 at 6:17
  • $\begingroup$ This video will help you understand where I am confused youtu.be/VycyIzulE68 see the 111 spacing in this video! Is that correct? $\endgroup$
    – Prathamesh
    Sep 8, 2019 at 6:29

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