Calculate the number of Frenkel defects per cubic meter in zinc oxide at 935˚C. The energy for defect formation is 2.51 eV, while the density for ZnO is 5.55 g/cm3 at this temperature. The atomic weights of zinc and oxygen are 65.41 g/mol and 16.00 g/mol, respectively.

Answer : The number of Frenkel defects per cubic meter in zinc oxide is,

Explanation :

First we have to calculate the number of lattice sites per cubic meter.

Formula used :

where,

= Avogadro's constant =

= atomic mass of zinc = 65.41 g/mol

= atomic mass of oxygen = 16 g/mol

= density of ZnO =

Now put all the given values in the above formula, we get:

Now we have to calculate the Frenkel defects per cubic meter.

Formula used :

where,

= energy for defect formation = 2.51 eV

k = Boltzmann constant =

T = temperature =

Now put all the given values in the above formula, we get:

Thus, the number of Frenkel defects per cubic meter in zinc oxide is,