• Title/Summary/Keyword: Piezoelectric$Bi_2O_3$

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Dielectric and Piezoelectric Properties of Microwave Sintered BNT-ST Ceramics (마이크로파 소성법으로 제조한 BNT-ST 세라믹스의 유전 및 압전 특성)

  • Lee, Sang-Hun;Kim, Seong-Hyun;Erkinov, Farrukh;Nguyen, Hoang Thien Khoi;Duong, Trang An;Han, Hyoung-Su;Lee, Jae-Shin
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.33 no.1
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    • pp.37-44
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    • 2020
  • This study investigated the microstructure and piezoelectric properties of lead-free 0.74(Bi1/2Na1/2)TiO3-0.26SrTiO3 (BNST26) piezoelectric ceramics sintered using a microwave furnace. For comparison, specimens were also prepared using a conventional furnace sintering (CFS). Average grain sizes of 2.4 ㎛ and 3.2 ㎛ were obtained in the sample sintered at 1,100℃ for 5 min using microwave sintering (MWS) and at 1,175℃ for 2 h using CFS, respectively. To quantify the changes in the microstructures and electrical properties according to the sintering conditions, the polarization hysteresis, bipolar and unipolar strain curves, and temperature dependence of permittivity were evaluated. As a result, it was determined that the Pmax (maximum polarization), Pr (remanent polarization) and Smax (maximum strain) values tend to increase with the average grain size. Based on these results, it is concluded that the MWS method can produce lead-free ceramics with superior performance in a relatively short time compared to the conventional CFS method.

A Study on the Pressure Sensor for the Direct Detection of the Approach to the Dangerous Power Facilities Using Pb-free BNKT Ceramics (무연 BNKT 세라믹스를 이용한 위해(危害)전력설비 접근 직접감지용 압력센서에 관한 연구)

  • Hong, Jae-Il;Yoo, Ju-Hyun
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.55 no.1
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    • pp.31-34
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    • 2006
  • A infrared rays sensor or ultrasonic sensor can detect the object at the narrow area, however a pressure sensor can detect man and animal at the wide area. It is necessary to manufacture the sensor by using Pb-free ceramics in the respect of environmental protection. Piezoelectric properties of ceramics added 0.2wt% $La_2O_3\;into\;0.96Bi_{0.5}(Na_{0.84}K_{0.16})_{0.5}+0.04SrTiO_3$ were 0.4 of kp, $31{\times}$10^{-3}Vm/N\;of\;g_{33}$. The output voltage of the pressure sensor is 0.48 V at 20 in$H_2O$. The output voltage of the pressure sensor with driving circuit is 9.8 V, 37 ms width.

Effects of High-Energy Ball Milling and Sintering Time on the Electric-Field-Induced Strain Properties of Lead-Free BNT-Based Ceramic Composites

  • Nga-Linh Vu;Nga-Linh Vu;Dae-Jun Heo;Thi Hinh Dinh;Chang Won Ahn;Chang Won Ahn;Hyoung-Su Han;Jae-Shin Lee
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.36 no.5
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    • pp.505-512
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    • 2023
  • This study investigated crystal structures, microstructures, and electric-field-induced strain (EFIS) properties of Bi-based lead-free ferroelectric/relaxor composites. Bi1/2Na0.82K0.18)1/2TiO3 (BNKT) as a ferroelectric material and 0.78Bi1/2(Na0.78K0.22)1/2TiO3-0.02LaFeO3 (BNKT2LF) as a relaxor material were synthesized using a conventional solid-state reaction method, and the resulting BNKT2LF powders were subjected to high-energy ball milling (HEBM) after calcination. As a result, HEBM proved a larger average grain size of sintered samples compared to conventional ball milling (CBM). In addition, the increased sintering time led to grain growth. Furthermore, HEBM treatment and sintering time demonstrated a significant effect on EFIS of BNKT/BNKT2LF composites. At 6 kV/mm, 0.35% of the maximum strain (Smax) was observed in the HEBM sample sintered for 12 h. The unipolar strain curves of CBM samples were almost linear, indicating almost no phase transitions, while HEBM samples displayed phase transitions at 5~6 kV/mm for all sintering time levels, showing the highest Smax/Emax value of 700 pm/V. These results indicated that HEBM treatment with a long sintering time might significantly enhance the electromechanical strain properties of BNT-based ceramics.

Dielectric and Piezoelectric Properties of Low Temperature Sintering PZN-PZT Ceramics with a variation of $Li_2CO_3$ Addition ($Li_2CO_3$ 첨가에 따른 저온소결 PZN-PZT 세라믹스의 유전 및 압전특성)

  • Lee, Yu-Hyong;Lee, Sang-Ho;Yoo, Ju-Hyun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.06a
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    • pp.307-307
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    • 2007
  • 압전액츄에이터 및 초음파진동자는 전자제품의 소형화 및 경량화, 의료기기, 모바일기기 및 소형로붓의 발전에 힘입어 그 활용범위가 넓게 확장되고 있다. 1960년 Smolenski등에 의해 $A(B_1,B_2)O_3$형 복합 페로브스카이트 구조를 갖는 강유전성 세라믹스에 대한 연구가 시작된 이래 $Pb(Co,Nb)O_3-Pb(Zr,Ti)O_3$, $Pb(Zn,Nb)O_3-Pb(Zr,Ti)O_3$, $Pb(Mg,Nb)O_3-Pb(Zr,Ti)O_3$ 등 3성분계 세라믹스의 유전, 압전 및 강유전 특성에 대한 많은 연구가 진행되어 왔다. 그러나 압전성이 우수한 세라믹스들은 Pb가 포함되어 있기 때문에 $1000^{\circ}C$ 이상에서 PbO가 급격하게 휘발되는 성질에 따라서 조성의 변동이 생겨 재현성이 어려우며 이를 방지하기 위하여 과잉 PbO를 첨가시키기 때문에 환경오염뿐만 아니라, 경제적인 측면에서도 많은 문제점을 가지고 있다. 소결조제를 이용한 산화물 첨가법은 PbO의 휘발을 억제하는 저온소결 방법중 가장 효과적인 방법으로 알려져 있다. 따라서, 본 연구에서는 적층형 압전액츄에이터로 사용하기위한 저온소결 압전세라믹스를 개발하기 위하여 PZN-PZT세라믹스에 $Li_2CO_3$, $Bi_2O_3$, CuO 를 소결조제로 사용하여 $Li_2CO_3$의 첨가량 변화에 따른 압전 및 유전 특성을 관찰하였다.

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Direct Determination of Cationic Disordering in Sodium Bismuth Titanate

  • Choi, Si-Young;Ikuhara, Yuichi
    • Applied Microscopy
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    • v.42 no.3
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    • pp.164-173
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    • 2012
  • The relaxor ferroelectric feature in lead-free perovskite oxides, where the dipoles are randomly oriented and they can be feasibly aligned parallel to the external bias, is attracting lots of attention in the field of piezoelectric materials science, since it is one of candidates to replace the toxic lead-based materials that are still being commercially used. However, the origin of relaxor characteristic and its related atomic structure are still ambiguous. In this study, $Na_{1/2}Bi_{1/2}TiO_3$, chosen as a model relaxor system, was found to exhibit a cationic-disordered atomic structure; and furthermore the nonpolar atomic structure and its related oxygen tilting were ascertained via annular bright field imaging skill. We also found that this cationic disordering gives rise to the local formation of atomic vacancies.

Effect of Initial Particle Size Distribution of (K0.5Na0.5)NbO3 Powders on Microstructure of Their Sintered Ceramics ((K0.5Na0.5)NbO3 세라믹스의 초기 분말 입도 분포가 소결체의 미세구조에 미치는 영향)

  • Yoo, Il-Ryeol;Choi, Seong-Hui;Cho, Kyung-Hoon
    • Journal of the Korean Society for Heat Treatment
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    • v.35 no.2
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    • pp.57-65
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    • 2022
  • In this study, the effect of the initial particle size distribution (PSD) of (K0.5Na0.5)NbO3 powders on the microstructure of sintered ceramics was investigated. (K0.5Na0.5)NbO3 powders with uni-, bi-, tri-, and quad-modal PSDs were obtained through a planetary ball-mill. For the specimens sintered at 1080℃, the growth of abnormal grains was promoted from the powders exhibiting quad- and tri-modal PSDs with a high content of large particles, resulting in a microstructure in which huge abnormal grains were predominant. However, as the number of peaks in PSD and the overall particle size decreased, the abnormal grain growth was suppressed and the grain growth of small particles started, resulting in a microstructure with a uniform grain size. For the specimens sintered at 1100℃, huge abnormal grains were not observed due to the decrease in the critical driving force for 2D nucleation even when powders with quad- and tri-modal PSDs were used. It was confirmed that when powder with unimodal PSD was used, a uniform microstructure that was not significantly affected by the sintering temperature could be obtained. The results of this study demonstrate that the microstructure of (K0.5Na0.5)NbO3-based ceramics can be controlled by controlling the particle size of the initial powder.