Preparation and electric properties of BaTiO₃-based PTC ceramics doped by gaseous rare earth

The modified BaTiO₃-based PTC ceramics are prepared by gaseous doping of rare earth La, Pr and Gd, and the change laws of the room temperature resistivity and the temperature-resistivity properties are studied. The experimental results show that the doped BaTiO₃-based PTC ceramics by gaseous rare earth have a significant decrease in room temperature resistivity. After La-gaseous doping, the room temperature resistivity of the different specimen is respectively descreased to 2.5 × 10⁵ Ω·m, 70.0 Ω·m, 220.0 Ω·m and 40.0 Ω·m. After Pr-gaseous doping, the room temperature resistivity of the different specimen is respectively descreased to 3.5 × 10⁴ Ω· m, 50. 0 Ω·m, 9. 6 Ω·m and 5. 0 Ω·m. After Gd-gaseous doping, the room temperature resistivity of the different specimen is respectively descreased to 1.3 × 10⁴ Ω·m, 98.5 Ω·m, 2.3 × 10⁴ Ω·m and 32.4 Ω· m. But the resistivities of the BaTiO₃-based PTC ceramics doped by liquid rare earth are all more than 10⁴ Ω·m. Being distinct from the BaTiO₃-based PTC ceramics doped by liquid rare earth, the BaTiO₃-based PTC ceramics doped by gaseous rare earth give a significant NTCR effect.