采用高分子网络凝胶法和液相包裹法相结合的液相法合成了BaTiO3基PTCR陶瓷粉体.首先用高分子网络凝胶法在较低温度下制备施主掺杂的BaTiO3基陶瓷粉体,利用DSC、TG、XRD、TEM等技术表征了凝胶中间体和由此得到的氧化物粉末的物理和化学性能,结果表明,在700℃下煅烧2h可获得单相的(Ba,Sr)TiO3粉体,粉体的平均粒径d50 为1.155μm.然后利用液相包裹法添加受主杂质和助烧剂,考察了所制备BaTiO3基PTCR陶瓷粉体的烧结性能及陶瓷制品的PTC特性,获得了室温阻值为17.5Ω,升阻比达104,阻温系数约为12%的PTCR.
Ultrafine BaTiO3-based powders used for making positive temperature coefficient of resistance (PTCR) were synthesized by two
chemical steps: polyacrylamide gel process and liquid phase coating process. Firstly, doped BaTiO3-based powders were synthesized by
polyacrylamide gel process at rather low temperature, and the physical and chemical characteristics of the gels and the precursor powders were
investigated by DSC, TG, XRD, TEM. The results showed that single phase of (Ba, Sr)TiO3 was obtained when the gel was calcined at 700℃
for 2h, and the mean diameter of grains d50 was 1.155μm. Secondly, acceptor and sintering aid were coated by an aqueous solution containing
acceptor and additive. The microstructure characterization and sintering behavior of the PTCR powders and PTC effect of the ceramic samples derived
from the PTCR powders were investigated. Ceramic samples with low room temperature resistance 17.5Ω, ratio of the maximum resistivity
to the minimum (Rmax/Rmin) 104 and temperature coefficient of resistivity (α) 12% were obtained.
参考文献
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