Study on diffuse dielectric anomaly at high temperature region in perovskite-type ferroelectric oxides페로브스카이트 구조의 강유전체에서 발견되는 고온 영역의 확산형 이상 유전 현상에 관한 연구

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The dielectric relaxation behavior at high temperature region (400~700℃) was investigated in various perovskite-type ferroelectric oxide systems. It is known as diffuse dielectric anomaly or rounded dielectric anomaly. It is commonly found at the same temperature range of 400~700℃ in various perovskite-type ferroelectric oxides such as $BaTiO_3$, $PbTiO_3$, $CaTiO_3$, $SrTiO_3$ and their solid solutions. Although previously suggested dielectric relaxation models explained partly the dielectric relaxation phenomenon of the diffuse dielectric anomaly, there have been still remained unclear. For example, the frequency dependence of the diffuse dielectric anomaly was perfectly understood by the Debye relaxation model. However, the temperature-dependent behavior of the diffuse dielectric has not been understood. Therefore, the dielectric relaxation behavior of the diffuse dielectric anomaly at high temperature region was systematically studied in both experimental and theoretical ways, in this study. In the first chapter, the diffuse dielectric anomaly was experimentally investigated in various perovskite-type ferroelectric oxides such as $BaTiO_3$ single crystal and ceramics, La-doped $PbTiO_3$ ceramics, and $Pb_{1-x}La_xZr_{0.4}Ti_{0.6}O_3(x=0, 0.01, 0.05, 0.1)$ ceramics. The effects of sintering atmosphere, heat treatment and additives on the diffuse dielectric anomaly were observed, which strongly confirmed that the diffuse dielectric anomaly was related with oxygen vacancies. Also, it was found that the diffuse dielectric anomaly was perfectly suppressed in highly donor-doped PLZT ceramic systems. The theoretical approach with Debye relaxation model was performed to understand the dielectric relaxation behavior of the diffuse dielectric anomaly in the second chapter. Conventionally, the relaxation time has been known as a main parameter between experimental results and the Debye relaxation model. However, the modified fitting method with the relaxation streng...
Advisors
Choi, Si-Kyungresearcher최시경researcher
Description
한국과학기술원 : 재료공학과,
Publisher
한국과학기술원
Issue Date
2002
Identifier
174578/325007 / 000965005
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 재료공학과, 2001.2, [ ix, 80 p. ]

Keywords

diffuse dielectric anomaly; dielectric relaxation; ferroelectric; perovskite; Debye relaxation model; 디바이모델; 이상유전현상; 유전완화; 강유전체; 페로브스카이트

URI
http://hdl.handle.net/10203/50238
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=174578&flag=dissertation
Appears in Collection
MS-Theses_Ph.D.(박사논문)
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