Nonstoichiometry, point defects and magnetic properties in Sr2FeMoO6−δ double perovskites

► Sr2FeMoO6−δ is stable at T=1200 °C at low pO2 only. ► Nonstoichiometry δ measured at 1200, 1100, and 1000 °C. ► Increase of oxygen vacancy concentration with lower pO2. ► Reduction of magnetization with increasing nonstoichiometry δ.