Phase transition and oxygen permeability of Pr0.6Sr0.4FeO3-δ ceramic membrane at high temperature

Abstract

Perovskite-type Pr0.6Sr0.4FeO3-δ (PSF) material was prepared by the sol-gel method and systematically evaluated as an oxygen transport membrane (OTM). The material was accompanied by a phase transition with the temperature elevated, and the detailed phase evolution process was accurately detected by the high-temperature in situ X-ray diffraction and the thermogravimetric analysis technologies. The phase transition is related to the oxygen vacancy concentration. The effects of phase transition on structural parameter, oxygen permeability, rate-controlling step, and stability were investigated. The high-temperature cubic phase has a higher thermal expansion coefficient than the orthorhombic phase, which is more favorable for the movement of lattice oxygen. Combining experimental results and oxygen permeation model, demonstrated that the phase transition leads to the rate-controlling step changing from bulk diffusion to oxygen interfacial exchange. Furthermore, the high-temperature cubic phase is beneficial to limit the migration of the Sr ions and ensure higher operation stability.