還元再酸化焼成した(Ba, Ca)TiO_3半導体セラミックスのPTC特性

概要

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Three electrode materials, nickel, palladium and plati num were tested about the ohmic contact to semicon ducting BaTiO_3 ceramics for the application in mul tilayer BaTiO_3 semiconductors with a positive tempera ture coefficient (PTO of receptivity. Semiconducting BaTiO_3 ceramics with nickel electrodes showed a good ohmic contact, while palladium and platinum elec trodes showed rectifying contacts at the junctions. Semiconducting BaTi0_3 ceramics with a PTC charac teristic of receptivity were fired at 1350℃ in a reducing atmosphere and then annealed at various temperatures in the cooling process and in various oxidizing at mospheres, with a view to fabricate multilayer PTC ce ramics having Ni metal or Pd Ni alloy as internal elec trodes. The receptivity anomaly of PTC characteristics increased with increasing oxygen concentration in the annealing atmosphere and with increasing anuealing temperature below 1200℃. The resistivities at room temperature were almost independent of the annealing conditions. The reoxidation in allnealing occurs proba bly only at grain boundaries.
社団法人日本セラミックス協会の論文
1994-03-01