Fabrication and PTCR Characteristics of Porous Barium Titanate Thermistors using Graphite Powders

  • Published : 1996.12.01

Abstract

New porous BaTiO$_3$ thermistors were fabricated using graphite powders (0 to 10 wt. %) and their porosities were in the range of 9.1% to 16.2%. As results of impedance analysis, it was confirmed that the pores affected the grain-boundary resistance and the bulk (grain interior) resistance was constant as about 25 $\Omega$ at room temperature. The magnitude of PTCR effect $(p_{max}/p)$ markedly increased from 3 orders to 7 orders without addition of any acceptor dopant such as Mn or Cr.

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References

  1. Solid-State Electron. v.3 Bariumtitanat Als Sperrschichthalbleiter W. Heywang
  2. J. Appl. Phys. v.76 no.2 Positive Temperature Coefficient of Resistivity Effect in Undoped Barium Titanate Ceramics M. Kuwabara
  3. J. Am. Ceram. Soc. v.73 no.11 Grain-Boundary Chemistry of Barium Titanate and Strontium Tiatanate: Ⅰ. High-Temperature Equilibrium Space Charge Y.-M. Chiang;T. Takagi
  4. Japanese R&D Trend Analysis, Report No. 6: Ceramic Sensors
  5. J. Am. Ceram. Soc. v.73 no.11 Interfacial Segregation in Perovskites: Ⅱ. Experimental Evidence S. B. Desu;D. A. Payne
  6. J. Am. Ceram. Soc. v.69 no.6 Compensating Defects in Highly Donor-Doped BaTiO₃ H. M. Chan;M. P. Harmer;D. M. Smyth
  7. J. Am. Ceram. Soc. v.55 no.2 PTCR Behavior of BaTiO₃with $Nb_2O_5$ and MnO₂Additivies T. Matsuoka;Y. Matsuo;S. Hayakawa
  8. J. Ceram. Soc. Jpn. v.102 no.3 PTCR Characteristics of Semiconducting (Ba, Ca) TiO₃Ceramics Fired in Reducing-Reoxidizing Atmospheres S. Tashiro;A. Kanda;H. Igarashi
  9. J. Am. Ceram. Soc. v.76 no.2 Grain Boundary Oxidation in PTCR Barium Titanate Thermistor A. B. Alles;V. L. Burdick
  10. Jpn. Patent 487455 H. Ueoka;K. Umeta
  11. J. Am. Ceram. Soc. v.64 no.11 Effect of Microstructure on the PTCR Effect in Semiconducting Barium Titanate Ceramics M. Kuwabara
  12. J. Am. Ceram. Soc. v.64 no.12 Influence of Stoichiometry on the PTCR Effect in Porous Barium Titanate Ceramics M. Kuwabara
  13. J. Appl. Phys. v.67 no.4 The Influence of Mn on the Grain-Boundary Potential Barrier Characteristics of Donor-Doped BaTiO₃Ceramics J. Illingsworth;H. M. Al-Allark;A. W. Brinkman;J. Woods
  14. Solid State Ionics v.11 The Electrical Characterization of Ceramic Oxides A. D. Brailsford;D. K. Hohnke