Question

Why are defects in the crystalline solids called thermodynamic defects?

Answer 1

There is perfect arrangement of the constituent particles only at 0 K. As the temperature increases the chance that a lattice site may be unoccupied by an ion increases. As the number of defects increases with temperature, the defects are called thermodynamics defect.

Answer 2

Defects or Imperfections in Solids. Any deviation from the perfectly ordered arrangement constitutes a defect or imperfection. These defects sometimes called thermodynamic defects because the number of these defects depend on the temperature. ... The electrons and holes in solids gives rise to electronic imperfections.