First-principles calculations were performed to evaluate the effects of alkaline-earth (M = Ba, Sr, Ca) doped monoclinic La2GeO5 on oxygen ion conduction. Electronic densities of states of the doped systems La1.75M0.25GeO4.75 showed insulating majority and semiconducting minority spin states while both the perfect La 2GeO5 and oxygen-deficient La2GeO 4.75 systems are electronically insulating. Oxygen vacancy formation energies decreased significantly in doped systems. We determined the activation barrier by performing climbing image nudged elastic band calculations. The similarity in ionic radii causes the lowest activation barrier in Ca-doped case, which is in agreement with an experiment. Consequently, Ca is the most favorable dopant to La site in La2GeO5.
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