| 摘要 |
<p>PURPOSE:To provide dielectric porcelain having improved characteristics, e.g. less variation in varistor voltage due to change of temperature, improved electrostatic capacity, less dielectric loss and improved thermal resistance in a soldering process, by applying a compound of K or Ag on the surface of a baked body and heat treating the same for diffusing either K or Ag ions into a region near the grain boundary of SrTiO3 porcelain crystals converted into a semiconductor. CONSTITUTION:Appropriate amounts of SrCO3, TiO2 and salts or oxides of M and M' are mixed to provide (Sr1-XMX)(Ti1-YM'Y). The mixture was baked and crushed to produce a first component. Powder of a material selected from Nb2O5 and others as second component and powder of one or more metal oxides selected from SiO2 and others are weighted appropriately and these powders are mixed and stirred. Polyvinyl alcohol is incorporated in the mixture for granulating the same and the granules are pressure molded into a disk, which is baked within reducing atmosphere. A fluoride or oxide of K or Ag is applied on the surface of the disk at 1.0 mg/cm<2>. The applied layer is heat treated at 800-1250 deg.C for 30 minutes in atmospheric air in order to diffuse K or Ag ions into semiconductor porcelain.</p> |
