Question

express the relationship between atomic radious and edge length in bcc and fcc. unit. cell

Answer 1

If a is edge length and r us radius then,

For BCC Structure,
a = 4r / (√3)

For FCC Structure,
a = 4r / (√2)

Answer 2

Hey dear,
Unit cell is the simplest repeating unit in a crystal.

● Answer -
In FCC, a = 2√2r
In BCC, a = 4r/√3

● Extra information -
Let, a = edge length, r = atomic radius.

In Simple cubic lattice,
Z = 1, r = a/2

In face centred cubic (FCC) lattice ,
Z = 4, r = a/2√2

In body centred cubic (BCC) lattice,
Z = 2, r = √3a/4

Hope this helped you.
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