What type of defect causes F -centers in a crystal ?
(a) Stoichiometric defect (b) Metal excess defect due to anion vacancies (c) Metal excess defect due to extra cations (d) Frenkel defect
(a) Stoichiometric defect (b) Metal excess defect due to anion vacancies (c) Metal excess defect due to extra cations (d) Frenkel defect