Question

Copper has face-centered cubic (fcc) lattice with interatomic spacing equal to 2.54 Å.The value of the lattice constant for this lattice is:

• A. 2.29 Å
• B. 3.29 Å
• C. 2.59 Å
• D. 3.59 Å

Answer 1

Answer: (D)

3.59 Å

Answer 2

Given interatomic spacing = 2r = 2.54 Å
In the FCC lattice, 4r=2 a , where a is the lattice constant.
2r= $\frac{\sqrt 2 a}{2}$=$\frac{a}{\sqrt 2}$
​ a=$\sqrt 2 r$×2
=(2.54Å )(1.414)=3.59Å