Sr-doped lanthanum scandate La
1−xSr
xScO
3−δ (LSS) is a promising perovskite-type material for electrochemical applications such as proton conductors. Oxygen vacancy is a common defect in
ABO
3-type perovskites. It controls ion transport as well as
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Sr-doped lanthanum scandate La
1−xSr
xScO
3−δ (LSS) is a promising perovskite-type material for electrochemical applications such as proton conductors. Oxygen vacancy is a common defect in
ABO
3-type perovskites. It controls ion transport as well as proton uptake. The energetic, structural, and electronic properties of oxygen vacancy in LSS are studied deploying the DFT method with meta-GGA functional. The vacancy formation energies in LSS were calculated for various Sr concentrations. Unlike other perovskites, in this material, the electrons are trapped at the oxygen vacancy site (the F-type centres, common in ionic oxides like MgO and Al
2O
3) rather than localised on the nearest to the vacancy
B-cations. The process of oxygen vacancy formation is considered relative to Sr concentration
x and oxygen nonstoichiometry factor
δ. Three primary regimes are discussed: (I) localized at the vacancy electrons,
x/
δ < 2, (II) electron charge balanced system,
x/
δ = 2, and (III) delocalized electron holes,
x/
δ > 2. For
x/
δ ≥ 2 oxygen vacancy formation energy reaches the saturation level of ~3.5 eV, which is potentially beneficial for the proton uptake.
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