Solid electrolyte sensors.--The solid-electrolyte-based
sensors owe their usefulness to the exceptionally high ionic
conductivity of the solid electrolyte material in the temperature
range of 773 to 1573 K. These have only one mobile
species and, in the case of oxide systems based on stabilized
zirconia, they find wide applications. An oxygen sensor
works on the principle of a concentration cell in which
oxygen ion conductor (stabilized zirconia) acts as the solid
electrolyte and also as a separator for the two compartments with gaseous mixtures having different oxygen potentials
or partial pressures. The galvanic cell