The electrical contact behavior between various electrodes(Ag, Ni, Au-Ti alloy) and PTCR ceramics was evaluated by a complex impedance analysis and an equivalent circuit conception. PTCR ceramics with ohmic-Ag and Ni electrodes exhibited a very low resistance in normal conditions. Ohmic-Ag and Ni were inappropriate for internal electrodes because ohmic-Ag vaporized above 1,000 oC and Ni oxidized above 400 oC. Au-Ti electrodes were deposited on the surface of PTCR ceramics by a sputtering method and the Au containing 3.00 wt% and 19.56 wt% of Ti showed non-ohmic contact behavior, while the Au containing 5.73 wt%, 10.84 wt% and 13.95 wt% of Ti showed ohmic contact and these Au-Ti electrodes exhibited good thermal stability up to 1300 oC.

Keywords: PTCR ceramics, Inner electrode, Ohmic contact, Co-firing.