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

[mikehibbert]

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? :)

 

[Mapes]

Atomic packing factor.

 

[mikehibbert]

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?

 

[Mapes]

Check your math.