FCC Crystal Problem: Nearest Neighbors, Bond Angles & Packing Fraction

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SUMMARY

The discussion focuses on the FCC (Face-Centered Cubic) crystal structure, specifically addressing the number of nearest neighbors, bond angles, and packing fraction. The correct number of nearest neighbors in an FCC structure is 12. The packing fraction, calculated using the atomic packing factor, is determined to be approximately 0.236 based on the volume of one atom and the volume of the crystal. The volume of one atom is given by the formula (π * (2^(3/2)) * (a^3)) / 48, where 'a' represents the lattice parameter.

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Homework Statement



Write down the number of nearest neighbours in a FCC structure, calculate the angle between the bonds and the packing fraction.

Homework Equations



Literally don't know where to start!

The Attempt at a Solution



Very confused at the moment. Tried to look up packing fraction in my Solid State texbook - but it isn't there?! Is there another name for it? Can someone point me in the right direction please? :)
 
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ok - could someone validate my answer please?

i got 4 atoms in one crystal,

the volume of one atom: ( pi * (2^(3/2)) * (a^3) ) / 48

the volume of the crystal is a^3

giving a packing fraction of 0.236?
 
Check your math.
 

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