• C R Zhou

      Articles written in Bulletin of Materials Science

    • Electrical properties of Sr𝑥Ba1−𝑥Fe0.6Sn0.4O3−𝜀 NTC thermistors

      C L Yuan X Y Liu J W Xu X W Zhang C R Zhou

      More Details Abstract Fulltext PDF

      Polycrystalline thermistor ceramics with the stoichiometric formula, Sr𝑥Ba1−𝑥Fe0.6Sn0.4O3−𝜀 (0.2 ≤ 𝑥 ≤ 0.8), had been prepared by a standard solid state reaction route. X-ray diffraction analysis indicates that the ceramic system remains cubic perovskite structure with a very small lattice change. The electrical properties of Sr𝑥Ba1−𝑥Fe0.6Sn0.4O3−𝜀 thermistors were studied using a digital thermometer over a wide range of 298–400 K. The thermistors showed an excellent negative temperature coefficient (NTC) thermistor behaviour. The values of resistivity at 298 K (ρ982), thermistor constant (𝐵298/358) and activation energy (𝐸a) of the Sr𝑥Ba1−𝑥Fe0.6Sn0.4O3−𝜀 thermistors, decreasing with the increase of Sr content, were in the range of 0.37–11.0 k𝛺.cm, 2466–3703 K and 0.212–0.319 eV, respectively. For the thermistors with the compositions 𝑥 = 0.2 and 0.4, the fitting equivalent circuit was composed of three RCPE elements corresponding to grain, grain boundary and ceramic–electrode interface, respectively. From the impedance plots, it was found that the fitting data showed good agreement with the experimental data. The extracted grain boundary resistance exhibited a NTC thermistor behaviour.

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