Solvent-free direct salt precursor mechanochemical synthesis of La0.5Sr0.5Ti0.5Mn0.5O3-δ oxide perovskite and its electrocatalytic behavior as oxygen electrode for solid oxide cells

Abstract

In this work, a solvent-free mechanochemical route is proposed as a direct salt precursor solid state synthesis for the mixed ionic-electronic conducting (MIEC) Lanthanum Strontium Titanium Manganese oxide perovskite (La0.5Sr0.5Ti0.5Mn0.5O3-δ, LSTM). The resulting mechanochemically synthesized powder is structurally and morphologically characterized and is comprised of fine spherical nanostructures in the sub-micron scale (≤100 nm), with low polydispersity and homogeneous morphology, while the obtained perovskite structure is pure single-phase without any precursor residuals or metal oxide phases. For comparison, conventional synthetic routes (sol-gel and precursor calcination) are presented which result in inferior samples of mixed metal oxides and micron-sized particles. Symmetrical solid oxide cells with single-phase LSTM and LSTM-YSZ composite electrodes reveal a mixed conduction behavior in the temperature range of 700–850 °C under flowing synthetic air atmosphere. With a developed current density of 172 mA cm−2 at 850 °C and +2 V overpotential, and an electrode polarization resistance of 7.5 Ω cm2, perovskite LSTM synthesized by the presented solvent-free direct salt precursor mechanochemical synthesis is therefore proposed as a potential candidate for MIEC electrodes in symmetrical reversible solid oxide cells (r-SOCs).