Preparation of Ni/BaTiO_3 Composites and PTC Effect

摘要

Ni/BaTiO_3 composite was prepared by decomposition of NiC_2O_4· 2H_2O/BaTiO_3 precursor, which was prepared by precipitating of nickel in the form of oxalate into the BaTiO_3 slurry. The composite must be sintered in reducing atmosphere. Otherwise NTC effect would be introduced. The prepared composite almost had no PTC effect. But PTC effect of the Ni/BaTiO_3 composite can be effectively renewed by heat-treatment in air. Under a proper composition and method, the composite shows low room-temperature resistivity (ρ_(RT) = 6.0 Ω·cm) and obvious PTC effect (ρ_(max)/ρ_(min) = 10~2).