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Tunability of Ba(Ti0.92Zr0.08)O3 Polycrystal Grown on Ceramic Seed by Floating Bone Technique

세라믹스 종결정 위에 Floating Zone Technique 법으로 성장한 Ba(Ti0.92Zr0.08)O3 다결정의 Tunability

  • Hwang, Ho-Byong (Department of Electronic Materials Science, Daejeon University)
  • 황호병 (대전대학교 전자재료과학과)
  • Published : 2004.10.01

Abstract

[ $Ba(Zr_{0.08}Ti_{0.92})O_3$ ] polycrystal was grown by floating zone technique with two ellipsoidal mirrors using the $8\%$of Zr-modified BZT ceramics as both a feed rod and a seed crystal. In order to study the annealing effect, a part of the grown crystal was sliced and annealed in the oxygen atmosphere at $1,200^{\circ}C$ for 10 h. The dielectric constant and loss at 10 kHz, 100 kHz, and 1 MHz were measured in the temperature range between $-100^{\circ}C$ and $150^{\circ}C$ to investigate the dielectric properties of the grown polycrystal. The electric-field dependence of the dielectric constant at 10 kHz and 100 kHz was studied by measuring the dielectric constants as a function of the biased-electric fields which ran from -15 kV/cm to 15 kV/cm. Due to the effect of annealing in the oxygen atmosphere, the electric-field tunability of dielectric constants increased from $47.5\%$ to 5 to and the figure of merit for this material from 39.6 to 46.4. Since the figure of merit can be increased to more than 46.4 by increasing the maximum value of the biased-electric fields to more than 15 V/cm, this material nay have a possibility for applications in microwave tuning devices at room temperature.

Zr을 $8\%$ 첨가한 BZT 세라믹스를 종결정과 소재봉으로 사용하여 floating zone technique법으로 $Ba(Zr_{0.08}Ti_{0.92})O_3$ 다결정을 성장하였다. 열처리 효과를 알아보기 위하여 성장한 결정의 일부를 떼어내어 $1,200^{\circ}C$에서 10시간동안 산소 분위기에서 열처리하였다. $-100^{\circ}C$에서 $+150^{\circ}C$ 온도 영역에서 유전상수 및 유전손실을 10kHz, 100kHz, 그리고 1 MHz에서 측정하여 성장 결정의 유전특성을 알아보았다. 상온($27^{\circ}C$)과 저온($-73^{\circ}C$)에서 직류전장(-15kV/cm$\le$E$\le$15kV/cm)을 인가하면서 유전상수의 변화를 10kHz와 100kHz에서 측정함으로써 유전상수의 전장의존성을 알아보았다. 산소 열처리는 상온에서 10kHz의 튜너빌리티를 $47.5\%$에서 $51\%$로, 그리고 성능지수를 39.6에서 46.4로 향상시키었다. 바이어스 직류전장을 15kV/cm 이상 인가하면 성능지수가 46.4 이상으로 향상될 수 있으므로 이 물질이 마이크로파 전장 조절 소자에 응용될 수 있는 가능성이 있다.

Keywords

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