Oxygen transport in epitaxial SrTiO<sub>3</sub>/SrTi<sub>1 − <i>x</i></sub>Fe<sub><i>x</i></sub>O<sub>3</sub> multilayer stacks

Abstract

Abstract. Nano-ionic materials made of strontium titanate (SrTiO 3 , STO) and solid solutions of strontium ferrite in STO (SrTi 1−x Fe x O 3 , STF) are grown on single crystalline STO substrates and characterized. Since STF exhibits an oxygen deficiency and, simultaneously, enables oxygen interstitial defects, a space charge area close to the STO | STF interface is present. Oxygen tracer diffusion experiments and impedance spectroscopy at temperatures from 500 to 700 • C and at oxygen partial pressure ranging from 10 −3 to 10 −23 bar confirm fast oxygen transport caused by enhanced ionic conductivity at the interface. There, an oxygen diffusion coefficient of 3.4 × 10 −10 m 2 s −1 at 600 • C and a p type conductivity of about 360 S m −1 at 700 • C are calculated. Such structures open new options in design of nano-ionic materials for oxygen sensors and energy conversion at temperatures lower than those of conventional materials such as yttrium-doped zirconia.