Advertisement

Journal of Materials Science

, Volume 25, Issue 7, pp 3333–3337 | Cite as

Preparation and properties of KNbO3 via the sol-gel method

  • Azar Nazeri-Eshghi
  • A. X. Kuang
  • J. D. Mackenzie
Papers

Abstract

Sol-gel processing of a solution of niobium and potassium ethoxides in methanol was used to prepare polycrystalline potassium niobate ceramic discs. Gel powders completely crystallized after only 2 h at 600 ° C. Crystallized powders were hot-pressed at pressures less than half of that required in conventional methods. Densities of up to 99% were achieved without encountering the common problem associated with the evaporation of the potassium oxide and subsequent formation of a stable second phase. The variation of dielectric constant with temperature was measured up to several degrees above the Curie temperature (ã420b ° C). Dielectric constants of dense samples were found to be more than one and one-half times greater than that of their single crystal counterparts.

Keywords

Potassium Dielectric Constant Niobium Curie Temperature Ethoxides 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    L. L. Bench andD. R. Ulrich, “Science of Ceramic Chemical Processing“ (Wiley, New York, 1986).Google Scholar
  2. 2.
    J. D. Mackenzie andD. R. Ulrich, “Ultrastructure of Advanced Ceramics“ (Wiley, New York, 1988).Google Scholar
  3. 3.
    C. Klien, “Sol-Gel Technology for Thin Films, Fibers, Preforms, Electronics and Specialty Shapes“ (Noyes, New Jersey, 1988).Google Scholar
  4. 4.
    E. T. Wu, K. C. Chen andJ. D. Mackenzie, “Better Ceramics Through Chemistry“, Vol. 32 (North-Holland, New York, 1984) pp. 169–74.Google Scholar
  5. 5.
    H. C. Graham, N. M. Tallan andK. S. Mazdiyazni,J. Amer. Ceram. Soc. 54 (1971) 548.Google Scholar
  6. 6.
    K. S. Mazdiyazni andL. M. Brown,ibid. 54 (1971) 539.Google Scholar
  7. 7.
    L. M. Brown andK. S. Mazdiyazni,ibid. 55 (1972) 541.Google Scholar
  8. 8.
    E. T. Wu, A. X. Kuang andJ. D. Mackenzie, Proceedings of the Sixth IEEE International Symposium on Applications of Ferroelectrics (ISAF, 1986), Lehigh University, pp. 388–90.Google Scholar
  9. 9.
    Idem, ibid. pp. 390–3.Google Scholar
  10. 10.
    U. Fuckiger andH. Arend,J. Crystal Growth 43 (1978) 406.Google Scholar
  11. 11.
    K. Kadokura, J. Shioya, S. Shimada andT. Matsushita,J. Mater. Sci. Lett. 1 (1982) 277.Google Scholar
  12. 12.
    D. C. Bradley, R. C. Mehrotra andD. P. Gaur, “Metal Alkoxides” (Academic Press, New York, 1978).Google Scholar
  13. 13.
    A. Nazeri-Eshghi, E. T. WU andJ. D. Mackenzie, to be published.Google Scholar
  14. 14.
    K. C. Chen, T. Tsuchiya andJ. D. Mackenzie,J. Non-Cryst. Solids 81 (1986) 227.Google Scholar
  15. 15.
    E. J. A. Pope andJ. D. Mackenzie,ibid. 87 (1986) 185.Google Scholar
  16. 16.
    Mary W. Colby, A. Osaka andJ. D. Mackenzie,ibid. 82 (1986) 37.Google Scholar
  17. 17.
    J. D. Mackenzie, “Amorphous Oxides from Gels“, in “Ultrastructure Processing of Advanced Ceramics” (Wiley, New York, 1988) pp. 589–601.Google Scholar
  18. 18.
    P. W. Whipps,J. Cryst. Growth 12 (1972) 120.Google Scholar
  19. 19.
    W. A. Bonner, E. F. Dearborn andL. G. Van Uitert,Amer. Ceram. Soc. Bull. 44 (1965) 9.Google Scholar
  20. 20.
    G. Shirane, H. Danner, A. Pavlovic andR. Depinsky,Phys. Rev. 93 (1954) 672.Google Scholar
  21. 21.
    E. T. Wu, personal communications (1989).Google Scholar
  22. 22.
    L. Egerton andD. M. Dillon,J. Amer. Ceram. Soc. 42 (1959) 438.Google Scholar
  23. 23.
    A. V. Turik, V. A. Tais'eva, I. P. Raevskii, L. A. Reznichenko andO. I. Prokopalo,Izvest. Akad. Nauk SSSR, Neorg. Mater. 14 (1978) 912.Google Scholar
  24. 24.
    E. G. Fesenko, G. L. Prokopalo, I. P. Raevskii, L. A. Reznichenko andA. E. Panich,Ferroelectrics 41 (1982) 133.Google Scholar

Copyright information

© Chapman and Hall Ltd 1990

Authors and Affiliations

  • Azar Nazeri-Eshghi
    • 1
  • A. X. Kuang
    • 1
  • J. D. Mackenzie
    • 1
  1. 1.Department of Materials Science and EngineeringUniversity of CaliforniaLos AngelesUSA

Personalised recommendations