Difference of Bi2O3 doping effect between vapor process and solid process on Ba1−xSrxTiO3 semiconducting ceramics

Doping process is very important for the properties of materials. The properties of the Ba1−xSrxTiO3 positive temperature coefficient resistance (PTCR) ceramics, in which Bi2O3 was doped by a new process called vapor doping method, have improved greatly. The resistance jumping can be increased to over eight magnitude orders and the temperature coefficient can be obtained as high as 40%/°C. While this was not the case by conventional solid doping method, the PTCR effect of the sample doped with solid Bi2O3 decreased with the increasing of doping content. The complex impedance analysis revealed that the change of grain boundary character by the doping with vapor Bi2O3 would be responsible for the enhancement of the PTCR effect of the Ba1−xSrxTiO3 ceramics.