**2.4 Characterization of the real structure and functional properties**

Genesis of the real structure of sintered functional layers and pellets was studied in details by X-ray powder diffraction, high resolution transmission electron microscopy and scanning electron microscopy with local elemental analysis by EDX. XRD patterns were obtained with an ARLX'TRA diffractometer (Thermo, Switzerland) using CuKα monochromatic radiation (λ=1.5418 Å) in 2θ range 5-90o. Transmission Electron Microscopy (TEM) micrographs were obtained with a JEM-2010 instrument (lattice resolution 1.4 Å, acceleration voltage 200 kV). Analysis of the local elemental composition was carried out by using an energy-dispersive EDX spectrometer equipped with Si(Li) detector (energy resolution 130 eV).

Transport properties were characterized by impedance spectroscopy and oxygen isotope heteroexchange. Conductivity was measured in air with a MO-10 Micro-Ohmmeter at 25 Hz frequency with four Ag paste electrodes placed symmetrically at a perimeter of the pellet. The oxygen mobility was characterized by the temperature -programmed oxygen isotope exchange (a static installation with MS control of the gas phase isotope composition at pO2 4 Torr). Performance of functional layers sintered by using different techniques was tested using respective devices: button-size fuel cells operating with wet H2–air feeds and reactors equipped with supported membranes operating in the mode of oxygen separation from air into He stream (Sadykov et al, 2010, 2011).
