서지주요정보
$Pb(Zn_{1/3}Nb_{2/3})O_3 - BaTiO_3 - PbTiO_3$ 에서 미세조직 및 유전특성에 미치는 PbO의 효과 = Effect of PbO concentration on microstructure and dielectric properties in $Pb(Zn_{1/3}Nb_{2/3})O_3 - BaTiO_3 - PbTiO_3$
서명 / 저자 $Pb(Zn_{1/3}Nb_{2/3})O_3 - BaTiO_3 - PbTiO_3$ 에서 미세조직 및 유전특성에 미치는 PbO의 효과 = Effect of PbO concentration on microstructure and dielectric properties in $Pb(Zn_{1/3}Nb_{2/3})O_3 - BaTiO_3 - PbTiO_3$ / 조의성.
저자명 조의성 ; Cho, Eu-Seong
발행사항 [대전 : 한국과학기술원, 1997].
Online Access 원문보기 원문인쇄

소장정보

등록번호

8007395

소장위치/청구기호

학술문화관(문화관) 보존서고

DMS 97003

휴대폰 전송

도서상태

이용가능

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반납예정일

초록정보

The relationship between microstructure and dielectric constant of $0.8Pb(Zn_{1/3}Nb_{2/3})O_3-0.1BaTiO_3-0.1PbTiO_3$ (mol) has been investigated. On varing PbO content, the microstructure and dielectric constant of specimens changed considerably. A perovskite single phase was formed in a specimen with 0.5 wt% PbO deficiency. When the PbO content was increased from this value, a liquid phase formed and was present between perovskite grains. With increasing PbO deficiency in the specimens, on the other hand, a pyrochlore phase and a ZnO phase were formed, as second phases. The size of pyrochlore grains was much larger than that of perovskite grains. The densification was much suppressed with decreasing PbO content. The dielectric constant showed the maximum value at -0.5 wt% PbO content. The presence of a second phase and the reduction in sintered density reduced considerably the dielectric constant. The liquid phase, however, was found to be worse than the pyrochlore phase for dielectric constant of the material. The effect of heat-treatment of sintered specimens was also studied. After sintering of the specimens with 0.5 wt% PbO deficiency at 1050℃ for 1h, the sintered specimens were heat-treated at 900℃, 950℃, 1000℃, 1025℃, or 1100℃ for 7h. The crystal structure and the dielectric constant of the sintered specimen changed significantly with heat-treatment temperature. With increasing heat-treatment temperature above 1000℃, the tetragonality of the specimen increased. With the tetragonality increase, the dielectric constant also increased from 22,000 (1000℃) to 26,000 (1100℃). In contrast to these changes in tetragonality and dielectric constant, the average grain size and the sintering density were not changed up to the heat-treatment temperature of 1025℃. It appears therefore that the main cause of the increase in dielectric constant by heat-treatment was the tetragonality increase. The increase in tetragonality during the heat treatment was studied by convergent electron beam diffraction (CBED). It was found that a grain consisted of a nucleus, a paraelectric region, and a ferroelectric region. The nucleus contained more Nb than the other regions. The nucleus had a tetragonal structure with a(=b)/ c ratio of 1/ 0.9755. The ferroelectric region had also a tetragonal structure with a(=b)/c ratio of 1/1.0219. During heat-treatment of the sintered specimens, low permittivity phases (nucleus and paraelectric region) became smaller, and high permittivity ferroelectric region grew in the grains. The increase in the ferroelectric region which had a tetragonal structure with one axis larger than the other two led to increase in tetragonality and dielectric constant. By a heat-treatment at 1100℃ for 7h, the nucleus and the paraelectric region disappeared completely in the grains; the dielectric constant increased by about 25%.

서지기타정보

서지기타정보
청구기호 {DMS 97003
형태사항 iv, 104 p. : 삽도 ; 26 cm
언어 한국어
일반주기 저자명의 영문표기 : Eu-Seong Cho
지도교수의 한글표기 : 강석중
지도교수의 영문표기 : Suk-Joong L. Kang
학위논문 학위논문(박사) - 한국과학기술원 : 재료공학과,
서지주기 참고문헌 : p. 102-104
주제 Relaxor
Microstructure
Pyrochlore
Liquid
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