한국재료학회지 (Korean Journal of Materials Research)

  • 제17권8호
  • /
  • Pages.442-446
  • /
  • 2007
  • /
  • 1225-0562(pISSN)
  • /
  • 2287-7258(eISSN)
한국재료학회 (Materials Research Society of Korea)
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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)
  • 발행 : 2007.08.27
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초록

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.

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