Electrochemical polarization of orthorhombic PbO

The effective ambipolar diffusion coefficient of orthorhombic PbO was determined using non-stationary electrochemical and chemical polarization resp. depolarization experiments. This diffusion coefficient was discussed on the basis of a general theory taking ionization processes into account. The ionic transport numbers were calculated from the steady states. By comparison with the results of concentration cells an upper limit for the possible contribution of neutral defects to the mass transport could be given. The complete polarization curves were shown to be comprised of ohmic, transfer and concentration overvoltages. By means of impedance spectra the kinetic parameters were determined as functions of temperature and O2-partial pressures.