Question

How could crystallographic defects affect thermal conductivity, give an example?

Answer 1

conductivity of crystal increases due to defects in a crystal

in a crystal all atoms are arranged perfectly there is no defect in that crystal. but it is ideal situation only.

most of the crystals have defects. while forming the crystal there may be some gaps or vacaincies are created this causes to crystal defect. in this case there may be some foreign molecules occupy the crystal.

Such defective sites are called vacancies. Foreign (extrinsic) atoms or ions may be present in crystals, replacing the primary particles that form the crystal or being incorporated among them.

so conductivity of crystal increases due to defects in a crystal