Korean Journal of Materials Research (한국재료학회지)

Materials Research Society of Korea (한국재료학회)
권호 표지
DOI QR코드

DOI QR Code

Low Temperature Sintering and Microwave Dielectric Properties of 0.85CaWO4-0.15LnNbO4 (Ln = La, Sm) Ceramics

  • Kim, Su-Jung (Department of Materials Engineering, Kyonggi University) ;
  • Kim, Eung-Soo (Department of Materials Engineering, Kyonggi University)
  • Published : 2007.08.27
Download PDF
⟨ Previous Next ⟩

Abstract

Microwave dielectric properties of $0.85CaWO_4-0.15LnNbO_4$ (Ln = La, Sm) ceramics were investigated as a function of the sintering temperature and $Li_2WO_4$ content from 0.8 wt.% to 1.5 wt.%. A single phase with tetragonal scheelite structure was obtained at a given composition ranges. For the specimens with $Li_2WO_4$, the sintering temperature could be effectively reduced from $1150^{\circ}C$ to $900^{\circ}C$ due to the enhancement of sinterability. Dielectric constant (K) of the specimens with $LaNbO_4$ and $SmNbO_4$ was increased with the increase of sintering temperature and/or $Li_2WO_4$ content. However, K of the specimens with $LaNbO_4$ was higher than that of $SmNbO_4$ due to the larger dielectric polarizability $(\alpha)$ of $LaNbO_4$ ($18.08{\AA}$) than that of $SmNbO_4$ ($16.75{\AA}$). With an increase of $Li_2WO_4$ content, Qf value of the specimens with $SmNbO_4$ was decreased, while that of the specimens with $LaNbO_4$ was increased. Temperature coefficient of resonant frequency (TCF) was increased with the increase of $Li_2WO_4$ content.

Keywords

References

  1. Q. H. Yang, E. S. Kim and y. J. Kim, Mater. Sci. & Eng. B., 79(2-3), 236 (2003) https://doi.org/10.1016/S0254-0584(02)00284-5
  2. S. Hirano, T. Hayashi, and A. Hattori, J. Am. Ceram. Soc., 74(6), 1320 (1991) https://doi.org/10.1111/j.1151-2916.1991.tb04105.x
  3. E. Nieto, J .F. Ferrandez, C. Moure, and P. Duran, J. Mater. Sci, Mater. Elec., 7, 55 (1996)
  4. E. S. Kim, S. H. Kim, J. Electroceram. 17(2-4),471(2006) https://doi.org/10.1007/s10832-006-8571-7
  5. M. I. Mendelson, J. Am. Ceram. Soc., 52(8) 443-6 (1969) https://doi.org/10.1111/j.1151-2916.1969.tb11975.x
  6. B. K. Hakki and P. D. Coleman, IEEE Trans. Microwave Theory Tech., 8, 402 (1960) https://doi.org/10.1109/TMTT.1960.1124749
  7. T. Nishikawa, K. Wakino, H. Tanaka and Y. Ishikawa, IEEE MTT-S Int. Microwave Symp. Dig.3, 277 (1987)
  8. P. Lui, E. S. Kim, and K. Y. Yoon, Jpn. J. appl. Phys., 40(9B), 5769 (2001) https://doi.org/10.1143/JJAP.40.1
  9. S. Hirano, T. Hayashi, and A. Hattori, J. Appl. phys., 77(10), 5341 (1995) https://doi.org/10.1063/1.359597
  10. E. S. Kim, B. S. Chun, B. S, J. D. Kim and K. H. Yoon, Mater. Sci. & Eng., B, 99, 243 (2003) https://doi.org/10.1016/S0921-5107(02)00470-1
  11. B. D. Silverman, Phys. Rev., 125, 1921 (1962) https://doi.org/10.1103/PhysRev.125.1921
  12. K. Kondo, M. Okuyama and Y. Shibata, Advance in Ceramics, 77 (1986)
  13. H. T. Kim, S. H. Kim, S. Nahm and J. D. Byun, J. Am. Ceram. Soc., 82(11), 3043 (1999)