Oxygen surface exchange kinetics and electronic conductivity of the third-order Ruddlesden-Popper phase Pr4Ni2.7Co0.3O10-δ
Publikationen: Beitrag in Fachzeitschrift › Artikel › Forschung › (peer-reviewed)
- FELMI-ZFE Institut für Elektronenmikroskopie und Nanoanalytik - Zentrum für Elektronenmikroskopie
- Technische Universität Graz
- Max‐Planck‐Institut für Festkörperforschung, 70569 Stuttgart
- Max Planck Institut für Festkörperforschung
The third-order Ruddlesden-Popper phase Pr 4Ni 2.7Co 0.3O 10-δ (PNCO43) was synthesized by a freeze drying process. Phase purity and crystal structure were determined by X-ray diffraction and Rietveld analysis. The electronic conductivity of a bulk sample obtained by a two-step sintering process was measured by the four-point dc van der Pauw method as a function of temperature (50 ≤ T/°C ≤ 800) and oxygen partial pressure (1 × 10 − 3 ≤ pO 2/bar ≤1). Dense thin-film PNCO43 microelectrodes were prepared by pulsed laser deposition and photolithography on yttria-stabilised zirconia substrates. The thin-films were characterized by X-ray diffraction, scanning electron microscopy, scanning transmission electron microscopy, and inductively coupled plasma optical emission spectroscopy. Individual resistive and capacitive processes were investigated with electrochemical impedance spectroscopy as a function of the oxygen partial pressure (1 × 10 − 3 ≤ pO 2/bar ≤1) and temperature (600 ≤ T/°C ≤ 850). Oxygen surface exchange coefficients k q, calculated from the resistance of the electrode, show relatively high values (e.g. k q = 1.5 × 10 − 6 cm s −1 at 800 °C and 2 × 10 − 1 bar pO 2). Chemical surface exchange coefficients k chem of oxygen were obtained from the peak frequency or the chemical capacitance as determined by impedance spectroscopy.