Effect of Ni Electrode on the Characteristics of BaTiO<sub>3</sub> Based PTCR Ceramics

In order to achieve cost-effective inner electrodes for the multilayer BaTiO 3 -based ceramics having a positive temperature coefficient of resistivity (PTCR), we fabricated Ni paste based on Ni powder and investigated the effect of Ni electrode on the performance of semiconducting BaTiO 3 ceramics. We adjusted the particle size of Ni powder (0.2μm, 0.6μm and 1μm) and incorporated them as the electrodes into both single-layer and laminated BaTiO 3 PTCR devices. The device samples were sintered at 1200oC for 30min in reducing atmosphere consisting of N 2 and H 2 (97:3 by volume ratio), and went through a post-sintering in-air heat treatment at 700-900oC in air which is necessary for the PTCR effect. The results indicate that Ni powder with lager particle size are more stable against post-sintering heat treatment, and the heating temperature needs to be optimized to overcome the trade-off between ohmic behaviors of Ni electrodes and the PTCR effect of BaTiO 3 -based semiconducting ceramics.