Question

with the help of a labelled diagram show that there are four octahedral voids per unit cell in cubic close packed structure
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Answer 1

Answer:

As we know any atom surrounded by six atoms creates an octahedral void. In fcc, body centre is surrounded by six atoms present at face centre. 

And hence one octahedral void is present at body centre of each unit cell.

No. of octahedral void at the centre of 12 edge =41×12=3

No. of octahedral void at body centre of =1

Total no. of octahedral void in ccp=3+1=4

Location of octahedral voids per unit cell of ccp or fcc lattice 

(a) at body centre of the cube and

(b) at the centre of each edge