 Solution

ID: past-exam-of-the-materials-science-course-of-the-university-of-cambridge/2022/paper-1/2/b/ii/solution

An oxygen vacancy has effective carrier charge

q_{v} = + 2 e

σ_{ion} = \frac{n _{v} ( 2 e ) ^{2} D _{v}}{k _{B} T}, σ_{ion} = 2.00 S m^{- 1}

T = 873.15 K

. The oxygen ions move oppositely to the vacancies and carry the same conventional current. This estimate assumes independently migrating vacancies, negligible correlation corrections, and negligible electronic contribution to the reported ionic conductivity.

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