Answer:
Creating vacancies in ceramics. Consider doping ZrO₂ with small concentrations of Nb205. The valence of Nb is 5. Assume that Nb ions sit in Zr ion sites
a. A substitutional defect will be produced.
b. With this dopping, the Nb increases electron band conduction and decreases oxygen anion conduction in ZrO₂.
Explanation:
(a) The defect produced by dopping a little concentration of Nb₂O5 with Nb in the +5 charge state is known as a substitutional defect.
(b) With this dopping, the Nb increases electron band conduction and decreases oxygen anion conduction in ZrO₂.
Moreover, if oxygen vacancies are rate-limiting defect, the corrosion of ZrO₂ decreases and if electrons are rate-limiting then the corrosion of ZrO₂ is accelerated.
