Abstract
Perovskite 구조의 PMT-PT계 고용체를 precursor columbite를 이용한 산화물 혼합법으로 제작하여 결정립의 성장과 상전이 현상을 분석하였다. <TEX>$1250^{\circ}C$</TEX>에서 4시간 유지하여 제작한 시편의 소결밀도는 이론밀도의 97% 이상이었고, 완전한 perovskite phase를 형성하였다. 치밀하게 소결 처리된 시편의 결정립의 크기는 <TEX>$6\sim8{\mu}m$</TEX>로 측정되었다. PMT-PT 고용체계는 복합 강유전 고용체의 전형적인 P-E 이력현상과 강한 진동수 분산특성이 관찰되었다. 특히 PMT가 70% 이하인 조성은 상전이 온도 이상에서도 자발분극이 완전히 소멸하지 않는 relaxor 특성을 보였으며, 유전상수와 유전손실의 큰 진동수 의존성을 보였다. Ferroelectric properties of the PMT-PT were also studied from the temperature dependence of hysteresis loops using a method slightly modified from Sawyer-Tower's. Dielectric, pyroelectric and piezoelectric properties of the ceramics in the system PMT-PT were investigated. The resulted densities of the PMT-PT ceramics system were greater than 97 % of the theoretical value. As observed SEM micrograph of the fracture surfaces of the PMT-PT ceramics system, the average grain sizes were increased about 3-5 <TEX>${\mu}m$</TEX> to 6-8 <TEX>${\mu}m$</TEX> with increasing sintering temperature. The specimens with PT<0.30 for PMT-PT solid solution system exhibited the dielectric and pyroelectric properties of a typical relaxor ferroelectrics. The composition with the maximum dielectric constant exhibits relatively superior pyroelectric and piezoelectric properties.
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