The activity of the project has been focused on:
i) developing low temperature electrolytes able to be integrated in microtechnologies. A new concept electrolyte has shown the potential to be used at temperatures approaching room temperature. BICUVOX has been selected as superior oxygen conducting electrolyte material, with forecasted operating temperature below 100 ºC. The high ionic conductivity, added to the high stability vs. pO2 proved in this LOW temperature range, anticipates the potential use of BICUVOX down to RT in a new family of non-heated solid state electrochemical systems. This opens up amazing possibilities for the fabrication of solid state devices fully integrated in CMOS technologies. (Journal of Materials Chemistry A 7.45 (2019): 25772-25778 (Hot Paper and cover image); Journal of the European Ceramic Society 39.2-3 (2019): 101-114.)
ii) understanding the effect of grain boundaries on the ionic conductivity and the catalytic properties of mixed-ionic electronic conductors with applicability in Solid Oxide Fuel Cells. In particular, it has been proven that strain-induced defects in grain boundaries of manganites deeply impact their functional properties by boosting their oxygen mass transport while abating their electronic and magnetic order. We were able to alter the grain boundary composition by tuning the overall cationic content in the films, which represents a new and powerful tool for engineering electronic and mass transport properties of metal oxide thin films useful for solid-state devices. (Advanced Materials 31.4 (2019): 1805360; Metal Oxide-Based Thin Film Structures. Elsevier, 2018. 409-439; Chemistry of Materials 30.16 (2018): 5621-5629; Solid State Ionics 299 (2017): APL Materials 7.1 (2019): 013205; Nature communications 12.1 (2021): 1-11).
iii) unveiling point defects concentration in transition metal oxide thin films. Especifically, the defect chemistry of a relevant material such as La1-xSrxFeO3-δ (LSF) with different Sr content has been studied by using a novel in-situ spectroscopic ellipsometry approach applied to thin films at intermediate-to-low temperatures. Through this technique, the concentration of holes in LSF has been correlated to measured optical properties and its evolution with temperature and oxygen partial pressure was determined. In this way, a systematic description of defect chemistry in LSF thin films in the temperature range from 350 to 500ºC has been obtained, which represents a step forward in the understanding of LSF for emerging low temperature energy and information technologies applications (Advanced Materials Interfaces 8.6 (2021): 2001881).
iv) integration of μSOFC into silicon technology to create a compact power generator for portable applications. The strategy followed consisted of a vertical stacking of all the components (fuel cells stack, fuel pre-processor unit, and a catalytic post-combustion unit), a heat management unit consisting of a heat exchanger and a thermal insulation. Each individual element has been designed and fabricated after the optimization of the manufacturing processes. Special effort has been performed in the improvement of the SOFC membranes, which is the most critical element of the device. Moreover, systematic work on sealing, encapsulation by 3D printed ceramic parts, design of microfluidic pathway and stacking of cells has been carried out (Journal of Physics: Conference Series. Vol. 1407. No. 1. IOP Publishing, 2019; Smart Sensors, Actuators, and MEMS VIII. Vol. 10246. International Society for Optics and Photonics, 2017; ACS applied materials & interfaces 13.3 (2021): 4117-4125).
