| 摘要 |
<p>PURPOSE:To obtain a ceramic varister having excellent characteristics in a laminated type and the like by adding specified sintering accelerator, semiconductor accelerator, oxygen conductive solid electrolyte and grain-boundary depletion-layer forming agent into perovskite type oxide powder whose main component is SrTiO3, molding the powder by mixing and compression, performing sintering and reduction, and performing heat treatment in an oxidizing atmosphere. CONSTITUTION:To perovskite type oxide powder whose main component is SrTiO3, the following materials are added: 0.1-5.0wt.% sintering accelerator which mainly forms liquid phase at high temperatures; 0.05-2.0wt.% semiconductor accelerator which mainly forms perovskite- phase solid solution; 0.1-10.0wt.% oxygen conductive solid electrolyte which also serves the role of a grain-growth controlling agent; and 0.2-7.0wt.% grain-boundary depletion-layer forming agent Sr(Mn1/2Ta1/2) which also serves as a grain-growth controlling agent. The materials are mixed and compressed, and the molded body is obtained. Thereafter, sintering and reduction are performed at 800-1,500 deg.C. Then, heat treatment is performed in an oxidizing atmosphere at 900-1, 150 deg.C. Thus an electrode 3 is formed. For example, platinum pastes for inner electrodes 2 are printed on a green sheets. The material is sintered in an atmosphere at 1,400 deg.C. Reduction is performed in hydrogen at 1,300 deg.C. Then, heat treatment is performed in atmosphere at 950 deg.C. Thus the outer electrode 3 is formed.</p> |
