Research On BaTiO₃-(Bi_0.5Na_0.5)TiO₃ Lead-free PTCR Ceramics

As the rule of “lead material forbidden” has been banned, the research and preparation of lead-free PTC has become the focus of current research, major electronics companies are actively looking for a new lead-free materials which can replace Pb. This paper mainly use(Na0.5Bi0.5)TiO3 as the lead-free material to increase the Curie temperature.In this paper, firstly, BNT powders were prepared by solid state method and polymer network method and sintering at different temperatures, found that:800 ? is the best sintered temperature. And then we discussed how the donor doping and the liquid phase doping effect on the properties of PTCR.For Y2O3 doping at Ba site, with the content of0.2%mol,the room temperature resistivity was 1.5×103?.cm, the Tc was about 155?, the resistance jump was 4 orders. For Nb2O5 doping at Ti site, with the content of2.0%mol,the room temperature resistivity was 0.3×103?.cm, the Tc was about 145?,the resistance jumps was 5 orders. then we study and make scheme for double donor doping.And when the content of Y2O3 and Nb2O5 was 0.12%mol and 0.08 mol, it got the best properties, its room temperature resistivity was 0.8×103?.cm, the Tc was about 156?.Meanwhile, we use the BNT powder made by polymer network method to prepare the PTC and use Nb2O5 as the donor. compare to solid-state method, the content of Nb2O5 increased from 0.2%mol to 0.12%mol,and its room temperature resistivity was0.5×103?.cm, the Tc was about 150?,the resistance jumps was 5 orders.then at the point of Y2O3 doped 0.12%mol,Nb2O5 doped 0.08%mol.we use BN and Li2 O as the liquid phase to effect the properties of PTCR.it was found that when sintered at 1320?,it got the best properties at the point of 0.5%mol BN. its room temperature resistivity was 0.3×103?.cm, the Tc was about 155.0 ?,the resistance jumps was 5orders.For the Li2 O,under 1320?,at the point of 0.5%mol Li2 O doped, it got the best properties, its room temperature resistivity was 0.3×103?.cm, the Tc was about 150?,the resistance jumps was 5 orders.At last, this paper discusses the effect of sintering process on the properties of PTCR.at 1300 ?,1310 ?,1320 ?,1330 ? under insulation0.5h,1.0h,1.5h,2.0h,it is found that the PTCR gets the best properties at 1320? with the insulation of 1h.