Discovering efficient and innovative materials for protonic ceramic cells requires the characterization of countless compositions. The knowledge of structural properties, hydration parameters, and electrochemical performances is essential for selecting the most promising electrolyte materials. However, traditional measurements are performed on individual samples and require extremely long stabilization times. A high-throughput approach was chosen to evaluate the electrochemical performance of hundreds of compositions inside the Ba(Ce,Sn,Zr)_0.8Y_0.1Yb_0.1O_3-δ (BCSZYY) ternary system. Thin film combinatorial libraries were produced by pulsed laser deposition on 100 mm diameter wafers. The composition gradient is obtained through alternate depositions of BaCe_0.8Y_0.1Yb_0.1O_3-δ (BCYY), BaSn_0.8Y_0.1Yb_0.1O_3-δ (BSYY), and BaZr_0.8Y_0.1Yb_0.1O_3-δ (BZYY) centered on three opposite edges of the substrate to recreate the ternary diagram. XY-resolved characterization techniques were performed to map the elemental, structural, and hydration properties of each composition inside the BCSZYY ternary system.

In particular, X-ray diffraction (XRD) was carried out to study the thin film structure. More than 300 diffractograms were collected on different positions of a single sample and analyzed through a custom-made code to calculate the pseudocubic cell parameter of the thin film. The resulting values of the "a" cell parameters range from 4.176 Å for the BSYY‑rich part, to 4.251 Å for the BZYY area, up to 4.418 Å for the BCYY one, in good accordance with the values obtained by Rietveld refinement for reference powders of single materials.

In situ measurements were performed at the DiffAbs beamline of the SOLEIL synchrotron by simultaneously collecting X-ray diffraction and fluorescence signals. XRF allowed the evaluation of the elemental distribution of the BCSZYY samples at room temperature and gave insight into thickness variation, complementary to spectroscopic ellipsometry results. A custom-made furnace was specifically developed to perform in situ XRD measurements on wide-surface thin-film samples at high temperatures in dry and wet conditions. The furnace consists of a hotplate and an X-ray transparent PEEK dome, allowing the control of temperature and atmosphere. Due to the large surface of the hotplate, the temperature distribution was calibrated using a platinum internal reference. The BCSZYY sample was subsequently measured in dry and wet N₂ to calculate the unit cell expansion due to water incorporation and to extract some information about hydration thermodynamics for the entire BCSZYY ternary system.

A custom-made setup for electrochemical impedance spectroscopy measurements is under construction to measure the conductivity of the entire ternary system. Electrochemical results will be related to the diffusion coefficients obtained using ¹⁸O₂, H₂¹⁸O, and D₂O isotopic exchange followed by Time of Flight Secondary Ions Mass Spectrometry (ToF-SIMS). Recently, we successfully applied this technique to combinatorial samples, and it will be systematically performed inside high-throughput procedures.