Structure and electrical properties of Al2O3 doped Ca–Ce–Ti–W–O NTC ceramics at high temperature

This essay mainly studies the electrical properties of Ca–Ce–Ti–W–O oxides negative temperature coefficient (NTC) thermistors. The as-sintered dense ceramics are two-phased, compounding of a scheelite CaWO 4 phase and a rutile TiO 2 phase. The existence of Ce 3+ , which causes the materials to exhibit semiconducting behavior, has been confirmed by XPS analysis. Electrical property studies reveal that ρ 25 ∘ C and B 300/600 °C are 3.9 × 10 6 ~ 2.9 × 10 7 Ω·cm, 4155 ~ 4426 K, respectively. The aging coefficient is 1.8–5.3% in the period of 200 h at 500 °C. With the Al 2 O 3 doping the aging coefficient can be further suppressed to the lowest value of 1.48% without deteriorating other parameters. Such kind of ceramic materials can be used to manufacture high temperature NTC thermistors.