Question

How schottky and frankel defect affect the density of crystal?

Answer 1

Schooty Defect

• Schottky defect occurs in those ionic crystals where difference in size between cation and anion is small.
• In Schottky defect, both cation and anion leave the solid crystal.
• The atoms permanently leave the crystal.
• One Schottky defect leads to the formation of two vacancies.
• Two atoms reduce from the crystal for each Schottky defect
• Due to vacancy formation, Schottky defect reduces density of the solid

Frankel defect

• Frenkel defect usually occurs in those ionic crystals where size of anion is quite large as compared to that of the cation.
• In Frenkel defect, only the smaller ion (cation) leaves its original lattice site; whereas, the anion remains in original lattice sites
• Here, atoms leave the original lattice site and occupy interstitial position. So atoms reside within the solid crystal.
• One Frenkel defect creates one vacancy and one self-interstitial defect.
• The number of atoms present in the crystal before and after Frenkel defect remains same.
• Density of the solid crystal before and after Frenkel defect remains same as no atom leaves the solid.