High-temperature reduction thermochemistry of SrVO3-δ

Abstract

Abstract The cubic SrVO 3 perovskite oxide is an attractive candidate for high-temperature energy applications due to its favourable features, such as multiple oxidation states cations, high structural and thermal stabilities, ability to accommodate large number of oxygen vacancies, and cost-effectiveness. Herein, the temperature dependent reduction properties of SrVO 3 have been studied in terms of oxygen vacancy concentrations using accurate first-principles calculations to reveal the effects of oxygen vacancy and temperature in the reduction aptitudes of SrVO 3-δ , δ = 0−0.125. The reduction capability of SrVO 3-δ was found to be significantly impacted by increasing oxygen vacancy concentrations and temperatures. Analyses of electronic properties and vibrational properties of SrVO 3-δ in terms of δ revealed the origin of this reduction behavior. The electronic structure analysis showed that the reduction of SrVO 3-δ upon oxygen vacancy formation is highly localized to the neighboring V 4+ t 2g states at the vicinity of the oxygen defect, irrespective of δ. A comparison of the vibrational density of states of the defect-free and defective SrVO 3-δ demonstrated that the ionic contributions to the phonon density of states, and hence to the thermal contributions into the SrVO 3-δ lattices, were significantly disrupted by the introduction of oxygen vacancies, which ultimately impacted to the temperature dependent reduction behavior of SrVO 3-δ .