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) What is the type of defects produced? (b) How will such doping affect the oxygen anion conduction in ZrO2?

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.