(a) Suppose that Li2O is added as an impurity

(a) Suppose that Li2O is added as an impurity to CaO. If the Li+ substitutes for Ca2+, what kind of vacancies would you expect to form? How many of these vacancies are created for every Li+ added?
(b) Suppose that CaCl2 is added as an impurity to CaO. If the Cl- substitutes for O2-, what kind of vacancies would you expect to form? How many of the vacancies are created for every Cl- added?