The sonochemical method is a novel synthesis route that takes advantage of the use of ultrasonic radiation to obtain different nanomaterials with an improvement in the process variables and material characteristics. In this work, two different synthesis routes to obtain a double perovskite structure were compared in detail. The Pechini synthesis method is a widely used and effective way to obtain this kind of structure by the formation of a cross-linked network of metal cations. Alternatively, in sonochemistry, chemical reactions occur with the application of powerful ultrasound radiation. The final characteristics of synthesized powders of La0.9Sr0.1Fe0.9Co0.1O3±δ (LSFC) were analysed thermally, structurally, morphologically and optically, and their transport properties were evaluated to determine their semiconductor character in a solid oxide fuel cell device and in photocatalytic processes. Structural results indicated a well crystallized perovskite structure with a single cubic phase. The cell parameter a (approx. 3.89 Å) and crystal size measurements (11–20 nm) were determined by Rietveld refinement for samples obtained by both synthesis methods. Thescanning electron microscope micrographs showed aggregates with homogeneous morphology and a uniform particle size distribution, with a rough and porous surface. Optical properties were determined by ultraviolet–visible spectrophotometry and photoluminescence, resulting in an Eg of 1.2 and 0.8 eV in samples from Pechini and sonochemistry, respectively.

IrO ₂ –Ta ₂ O ₅ mixed metal oxide (MMO) coatings supported on metallic Ti are widely employed as anodes for the oxygen evolution reaction (OER) in acidic media. In this work, the effect of calcination process on the formation mechanism, microstructure, and electrochemical performance of IrO ₂ –Ta ₂ O ₅ coatings prepared by thermal decomposition of chloride precursors was systematically investigated. Thermo-gravimetric analysis coupled with Fourier transform infrared spectroscopy on evolved gas revealed the release of H ₂ O and HCl during the thermal treatment, suggesting that hydrolysis-assisted reactions contribute to the MMO formation. Scanning electron microscopy coupled with energy-dispersive x-ray spectroscopy and x-ray powder diffraction analyses showed the formation of semicrystalline coatings consisting of rutile IrO ₂ crystalline particles dispersed in an amorphous Ta ₂ O ₅ matrix. Increasing the calcination temperature promoted the IrO ₂ crystal growth and induced a progressive morphological transition from acicular structures to pseudo-cubical and elongated polyhedral systems. Electrochemical characterization demonstrated a trade-off between activity and durability, with lower calcination temperatures favoring a higher activity and higher calcination temperatures improving operational stability. These findings provide valuable guidelines for optimizing MMO anodes for acidic OER applications.