Hi,(adsbygoogle = window.adsbygoogle || []).push({});

In the solid form FeO, CoO and NiO all has the NaCl-structure (simple cubic). In a series of diffraction experiments with x-rays ([tex]\lambda = 0.15406~\text{nm}[/tex]) one found reflexes from the (111), (200) and (220)-planes with the following [tex]\theta[/tex]-values ([tex]\theta[/tex] is the angle in Bragg's law, [tex]2d\sin\theta=\lambda[/tex]):

FeO: 18.04 20.95 30.28

CoO: 18.26 21.20 30.77

NiO: 18.63 21.64 31.45

The first number is the angle corresponding to the reflection from the (111)-plane, the second number corresponds to reflection from the (200)-plane and the third from the (220)-plane.

Question: What are the axis length for the three unit cells? Any hints?

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Bragg diffraction

**Physics Forums | Science Articles, Homework Help, Discussion**