无铅BaTiO_3系热敏电阻及其PTC性能的研究进展

Research Progress of BaTiO_3-based Lead-free Thermistor Ceramics and Their PTC Effects

通常在BaTiO3中固溶PbTiO3来提高BaTiO3系PTCR的居里温度,但是铅的毒性和挥发性限制了BaTiO3系PTCR的应用,因此需要研制出高居里点的无铅PTCR陶瓷。随着BNT、BKT含量增加,BaTiO3系PT-CR的居里点升高,但同时室温电阻快速增大。若在提高居里点的同时抑制室温电阻率的增大,就能制备出有实用价值的无铅高居里点的PTC材料。综述了BNT、BKT的含量对居里温度的影响及其机理,通过加入还原剂或在还原气氛下烧结并制定合理的烧结制度可以得到低室温电阻率和性能较好的PTC材料。

PbTiO3 （PT） is usually added to the BaTiO3 to shift the Curie temperature （Tc） of BaTiO3-based positive temperature coefficient of resistivity （PTCR） to high temperature, but Pb is toxic and prone to volatilize, which restrict the use of lead contained BaTiO2-hased PTCR. Therefore, it is necessary to develop high T, lead-free PTCR ceramics. The Tc of BaTiO3-based PTCR was shifted to a high temperature with an increase of the BNT or BKT content, but the room temperature resistivity also increased simultaneously. If the Curie temperature is high and the room temperature resistivity is low, the lead-free high Curie temperature PTC materials that have practical value will be prepared. The effects of BNT or BKT content on Tc are summarized and the mechanism of T, increasing is also reported. The low room temperature resistivity thermistor with good PTC effect can be fabricated by joining reducing agent or sintering at reducing atmosphere with reasonable sintering procedure.