| 摘要 |
<p>PURPOSE:To obtain a thermally stable varistor which does not transit up to approx. 1000 deg.C by employing 50% or more of total bismuth of pyrochlore type compound as segregate interposed in grain boundary segregated part of crystal grains in a sintered material. CONSTITUTION:Ceramic powder containing at least one type selected from CaO, BaO, SrO, PbO, La2O3, Ce2O3, Pr2O3, Nd2O3, Pm2O3, Sm2O3, Eu2O3, Gd2O3, Dy2O3, Ho2O3 as metal additive in a material containing as main ingredients ZnO, MgO, and as sub ingredients at least Bi2O3, Nb2O5 of Bi2O3, Nb2O3, Sb2O3. CoO. Cr2O3, NiO, MnO in such a manner that the relationships between the additive and bismuth, and between niobium and the mismuth are Me/Bi=0.05-0.5, Nb/Bi=0.2-2.0, containing 0.05-1.0mol% of Bi2O3 is granulated, baked at 1000-1300 deg.C to obtain a plate-like sintered material. Both side surfaces of the sintered material are seized, plated or metallized with silver, thereby forming an electrode.</p> |
