Question

Explain briefly why the transparency range of single-crystal NaCl is much greater than for single- crystal MgO.

Answer 1

The transperancy range of single crystal NaCl is mcuh greater than for single crystal MgO.

The reason behind the transperancy is due to band gaps and void space , parctile size ,crystalstructure.

The crystal having large band gaps has more transperent than the smaller band gaps. In the question Nacl has larger band gap compared to Mgo. NaCl has 7.9eV to 8.5 eV band gap

MgO band gap nearly 6eV to 6.3 eV. Those are experimental values (approximate) not accurate.

lower band gap materials will absorb the incident radiation and will be opaque. higher band gap materials do not absorb incident elctromagnetic radiation. These reflects the light and will be transperent.

we will not say transperancy based on single factor. its a combination of factors to consider crystal transperent or not.

Amount of void space available to the light to travel through the material and size of particle and scattering of light also the factors of transperancy.