A fast proton conducting glass with proton transport number tH = 1 was successfully prepared by using conventional melting method. In-situ FTIR (Fourier transform infrared) measurements under hydrogen atmosphere, temperature of 300°C and applying 1 V between Pt electrodes were carried out in order to monitor the proton concentration. The electrode reaction on Pt in these conditions is similar to that under intermediate-temperature fuel cell operation. It was found from the in-situ FTIR measurements that the absorbance around 2900 cm-1 increases clearly after applying 1 V, whereas no significant change was observed around 3400 cm-1. Proton infiltration into the glass is discussed based on the in-situ FTIR and impedance results.

Density functional theory calculations are used to study the equilibrium energetics of protons on the surface and in the bulk of Y-doped BaZrO3. It is shown that protonic species in direct contact with Y dopants have energies lower than in perfect BaZrO3 by up to 0.4 eV. This energetic stabilization is achieved when the protonic species is in direct contact with two Y dopants. On the (001) surface of BaZrO3, protonic species are found to be energetically more stable than in the bulk by 1.1 eV and 1.6 eV on the BaO and ZrO2 surface terminations, respectively. At these terminations, the energy of protons recover the bulk value after penetrating three surface layers, and the energy cost associated with bulk incorporation is larger than 1 eV.

We will briefly review in situ synchrotron x-ray investigation of model thin film cathode systems for solid oxide fuel cells. The film cathodes examined in this study are (La,Sr)MnO3_δ (LSM), (La,Sr)CoO3_δ (LSC), and La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) thin films epitaxially grown on YSZ single crystal substrates by the pulse laser deposition technique. We find in all cases that Sr is enriched or segregated to the surface of the film cathodes. We concluded that the Sr enrichments or segregations are mainly the results of annealing because they do not depend on whether the cathodes are electrochemically biased or not during annealing. However, at least in the case of LSCF, we find that B-site Co segregates rather uniformly to the surface and the segregation responds sensitively and reversibly to the electrochemical bias.

The oxygen conductor yttria-stabilized-zirconia (YSZ) is widely used in miniaturized solid oxide fuel cells (µSOFC) and may be suitable for solid state ion emitter applications e.g. as miniaturized ion engines for electric propulsion. Since the YSZ films are not completely free of stress during the growth, cracks in fabricated free-standing membranes are often observed.

YSZ thin films were deposited on silicon substrates by radio frequency sputtering. Free-standing YSZ membranes were fabricated by partially removing the Si substrate by anisotropic wet-chemical etching using different masking patterns defined by electron beam lithography. We show how different sizes and etching conditions influence the strain in the fabricated membranes. To characterize these membranes we used optical microscopy and scanning electron microscopy.