Conductivity and aging behavior of Sr(Ti0.6Fe0.4)1−xO3−δ mixed conductor materials

Abstract

Perovskite materials play a significant role in oxygen sensors due to their fascinating electrical and ionic conductivities. The sol–gel technique was employed to prepare various compositions of B-site-deficient Fe-doped SrTiO₃ (iron-doped strontium titanate) or Sr(Ti_0.6Fe_0.4)_1−xO_3−δ, where x = 0.01, 0.02, and 0.03. The XRD results revealed that the principle crystalline phase of the samples was the cubic perovskite structure. The B-site deficiency improved the ionic and total conductivities of Sr(Ti_0.6Fe_0.4)_1−xO_3−δ. A small polaron conduction behavior occurred in the total electrical conductivity. The XPS results showed that the oxygen vacancy value decreased with the rise in the amount of B-site deficiencies. A lower B-site deficiency amount could produce more oxygen vacancies in the lattice but resulted in the ordering of vacancies and then lower ionic conductivity. The aging behavior was caused by the ordering of oxygen vacancies and resulted in a degeneration of electrical features under a long service time. Conversely, augmentation of the B-site deficiency amount inhibited the tendency for the ordering of oxygen vacancies and then promoted the electrical performance under a long usage time. The conduction mechanism of oxygen ions through oxygen vacancies was thoroughly investigated and discussed. The current study presents a feasible approach to ameliorate the physical features of conductors through doping the B-site of the perovskite layer with Fe, which would be a fruitful approach for numerous applications, including oxygen sensors and fuel cells anodes.