Electronic properties of Ca doped LaFeO3: A first-principles study

• Energetics of intrinsic and extrinsic defects and defect clusters in Ca-doped LaFeO3 is investigated using DFT.
• Electronic and magnetic properties of various defects and their defect levels in the band gap are calculated.
• Formation energies of oxygen vacancies are found to be significantly influenced by the Ca doping.
• A weak interaction between oxygen vacancies and dopants exists, suggesting a high mobility of oxygen vacancies.
• These findings suggest an enhanced conductivity of oxygen in LaFeO3 under Ca doping.

Acceptor doping of oxides generally results in the formation of charge-compensating oxygen vacancies, leading to enhanced ionic conductivity. Ca-doped LaFeO3 is one such example which has been considered for use in cathode materials of solid oxide fuel cells. In the present work, we determine the structural, electronic, and magnetic properties of individual intrinsic and extrinsic point defects and defect clusters in Ca-doped LaFeO3. We find that the concentration of oxygen vacancies can increase through the formation of dopant-vacancy clusters. Oxygen vacancy concentration will influence the diffusivity of oxygen which in La-based perovskites is shown to be governed by the oxygen vacancy concentration. We also calculate the interaction between dopant ion and oxygen vacancies and find that oxygen vacancies will not be trapped by the dopant species as found in other oxide materials. These findings suggest an enhanced conductivity of oxygen in LaFeO3 under Ca doping.