| 摘要 |
<p>PROBLEM TO BE SOLVED: To make low the specific resistance of a positive temperature coefficient thermistor and to make high the withstand voltage of the thermistor by a method wherein the thermistor contains a barium titanate composition as its main component and contains a semiconductivity-imparting element and an SrTiO3-x as its subcomponents. SOLUTION: A BaCO3 , a PbO, a TiO2 an Nb2 O5 an SiO2 and an MnO2 are respectively weighed so that the BaCO3 , the PbO, the TiO2 , the Nb2 O5 , the SiO2 and the MnO2 are composed into a composition of (Ba0.90 )TiO3 +0.02 SiO2 +0.001 MnO2 +0.002 Nb2 O5 . At the same time, SrTiO3 (ST) powder subjected to reduction treatment at 1100 deg.C in 4% of H2 green gas is weighed and all of the weighed BaCO3 , PbO, TiO2 , Nb2 O5 , SiO2 , MnO2 and ST powder are subjected to wet mixing by a ball mill. The ST powder is made into a structure, wherein the ST powder has an oxygen defect with an SrTiO3-x (3>x). This mixture is dried and thereafter, is calcinated for two hours at 1050 deg.C. The mixture is again subjected to wet grinding by the ball mill and is dried. A binder is added to this dried ground powder, the ground powder is granulated and the granules are molded into a 20-mm diameter and 2.5-mm thick disc shape at a pressure of 800 kg per one square centimeter. This molded material is baked in the air for two hours at 1300 deg.C.</p> |
