The Preliminary Research Of The System With The BT-BKT Lead-Free PTC Ceramics

Due to the restrictions of hazardous substances for imports and exports from EuropeanUnion lead-free PTC has been studied during the recent years, it has become a hot spot. Itbelongs to environmentally friendly material and also can be used in electronicsinformation, lead-free PTC has abroad prospects.the power of BKT and BT were prepared, meanwhile we also selected the differenttemperatures to sinter, it was sure that the power of BKT should be sintered at800℃, andthe power of BT should be sintered at1150℃. In order to obtain the decent performance, inthe experiment we also change the technological process. In the second we study the systemof BT-BKT, and obtained the property of PTC but also the lower room-temperatureresistivity. We chose the content of5mol%, sintering temperature of the powers was alsoconsidered. the room temperature resistivity of the ceramic was3.5×10⁴Ω.cm, Curietemperature was156.8℃and the ratio between the maximum resistance and the minimumresistance was103.In the end we chose the different experimental ion-doped PTC ceramicsto discuss the PTC property. We chose Sm3+and Nb5+as donor-doped elements. We foundit difficult to achieve semiconducting ceramics using trivalent-doped, but Nb5+can get alower room temperature resistivity. We also used the equivalent of Ca²⁺ions to dope, themechanism was discussed and the optimum content was5mol%.In this paper the PTC ceramic with low temperature resistivity and high Curietemperature point was prepared by solid-phase, room temperature resistivity was2.7×103Ω.cm, Curie temperature is156℃,the ratio between the maximum resistance and theminimum resistance was1.56×10⁴,temperature coefficient of resistance was9.19%/℃...