Oxygen vacancy-transition metal-ion impurity association in SrTiO3

The progressive reduction of SrTiO₃:Mn has been monitored by EPR. The results show the conversion of Mn⁴⁺ to Mn²⁺ and Mn²⁺ to Mn²⁺-V₀ by oxygen-vacancy capture. The latter defect association takes place with the copious oxygen vacancies produced during high-temperature reduction between 1100 - 1300 K. At still higher reduction temperatures, other defects are formed. Analysis of the temperature dependence of the defect association gives a value of 0.7 eV for the enthalpy of association.