Nanocrystalline semiconducting donor-doped BaTiO3 ceramics for laminated PTC thermistor

Abstract

This paper proposed a two-stage thermal processing method combined with the reduction-reoxidation procedure. Samples were firstly sintered in a reducing atmosphere by two stages and then reoxidized in air. Such two-stage thermal processing method was used to adjust density and grain size of ceramics separately. Finally, nanocrystalline semiconducting donor-doped BaTiO3 ceramics were first successfully prepared. Samples with average grain size of 340nm exhibited unexpectedly low room resistivity of 136Ωcm and a significant PTCR effect, with a resistance jump of 4 orders of magnitude. In addition, depletion layer thickness of 40nm and surface acceptor-state densities of 9.52×1013cm−2 were also calculated. Such good properties had not been reported in former publications. It also means that smaller components based on semiconducting BaTiO3 ceramics could be produced and more extensive application field could be proposed in the trend of miniaturization of electronic devices.