AN ESTIMATION OF THE ELECTRODE-ELECTROLYTE CONTACT AREA BY LINEAR SWEEP VOLTAMMETRY IN PT ZRO2 OXYGEN ELECTRODES/

The contact area between the platinum paste electrode and the zirconia electrolyte was estimated on the basis of a linear relationship betwe en the peak area of linear sweep voltammetry and the actual contact ar ea. The latter area was measured by microscopic observation of the con tact area from one side of a transparent zirconia single-crystal disk on the other side of which the platinum paste had been sintered. Apply ing the peak area vs. contact area relationship obtained to the same p latinum electrode sintered on polycrystalline zirconia disks, the cont act area was estimated from the voltammogram peak. The electrode perfo rmance increased monotonically with increasing contact area, but there was a small deviation from the proportional relationship. This deviat ion was corrected by using the length of the three-phase boundary, ins tead of the contact area, as a morphological parameter.