Selection of material for infiltration of non-stoichiometric Sr0.95Ti0.3Fe0.7O3-δ

The porous electrodes used for the infiltration were prepared from A-site non-stoichiometric Sr0.95Ti0.3Fe0.7O3-δ synthesized by the conventional solid state reaction method. Screen printed electrodes (0.5 cm2) on CGO-20 substrate, were fired at 800 °C for 2 hours in an air atmosphere. Infiltration of the scaffolds was performed by a water-based precursor solution of (La0.6Sr0.4)0.98CoO3 (LSC) and Ce0.8Gd0.2O1.9 (CGO). A mixture of water and ethanol (9:1 by vol.) with dissolved nitrates of La, Sr, and Co (Sigma Aldrich, >99%) and Pluronic P123 (Sigma Aldrich, Mn ~5800) surfactant was used. The prepared precursor solution was ~0.6 M with ~0.1 g of P123 per 100 ml. After the infiltration step, the samples were dried at 80 °C and heated in a furnace up to 350 °C for 10 mins. The process was repeated until a total of 10% weight gain was obtained for the electrodes on both sides. At the end, the samples were heated up to 600 °C.
Symmetrical electrode cells were tested in a 4-wire compression cell using electrochemical impedance spectroscopy (EIS) using a Novocontrol Alpha-A with a ZG-4 interface. The measurements were carried out at an amplitude of 25 mV in the frequency range from 3 MHz to 0.05 Hz in synthetic air (AirLiquide, 4N). Symmetrical samples were tested by in situ cyclic heating up to 600 °C ÷ 800 °C and cooling down progressively to 400 °C.
Presented in this dataset results are obtained at 700 °C after cooling from 750 °C. This dataset also contains the results of the DRT analysis of the presented EIS results.
As can be seen, infiltration of the STF-x electrode with a mixed ionic and electronic conductive material significantly improves the results, while infiltration with a material with pure ionic conductivity worsens the results.