• Title/Summary/Keyword: $(Bi_{1/2}Na_{1/2})TiO_3-SrTiO_3$

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Structural, Dielectric and Field-Induced Strain Properties of La-Modified Bi1/2Na1/2TiO3-BaTiO3-SrZrO3 Ceramics

  • Hussain, Ali;Maqbool, Adnan;Malik, Rizwan Ahmed;Zaman, Arif;Lee, Jae Hong;Song, Tae Kwon;Lee, Jae Hyun;Kim, Won Jeong;Kim, Myong Ho
    • Korean Journal of Materials Research
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    • v.25 no.10
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    • pp.566-570
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    • 2015
  • $Bi_{0.5}Na_{0.5}TiO_3$ (BNT) based ceramics are considered potential lead-free alternatives for $Pb(Zr,Ti)O_3$(PZT) based ceramics in various applications such as sensors, actuators and transducers. However, BNT-based ceramics have lower electromechanical performance as compared with PZT based ceramics. Therefore, in this work, lead-free bulk $0.99[(Bi_{0.5}Na_{0.5})_{0.935}Ba_{0.065}]_{(1-x)}La_xTiO_3-0.01SrZO_3$ (BNBTLax-SZ, with x = 0, 0.01, 0.02) ceramics were synthesized by a conventional solid state reaction The crystal structure, dielectric response, degree of diffuseness and electric-field-induced strain properties were investigated as a function of different La concentrations. All samples were crystallized into a single phase perovskite structure. The temperature dependent dielectric response of La-modified BNBT-SZ ceramics showed lower dielectric response and improved field-induced strain response. The field induced strain increased from 0.17%_for pure BNBT-SZ to 0.38 % for 1 mol.% La-modified BNBT-SZ ceramics at an applied electric field of 6 kV/mm. These results show that La-modified BNBT-SZ ceramic system is expected to be a new candidate material for lead-free electronic devices.

Electrical Properties of 0.77(Bi1/2Na1/2)TiO3-0.23SrTiO3 (BNST23)/PVDF-TrFE Composites (스마트 페인트 센서용 0.77(Bi1/2Na1/2)TiO3-0.23SrTiO3 (BNST23)/PVDF-TrFE 복합소재 제조 및 전기적 특성에 관한 연구)

  • Sung Jae Hyoung;Eun Seo Kang;Yubin Kang;Chae Ryeong Kim;Chang Won Ahn;Byeong Woo Kim;Jae-Shin Lee;Hyoung-Su Han
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.37 no.4
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    • pp.433-438
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    • 2024
  • Piezoelectric ceramics play an important role in various electronic applications. However, traditional ceramics are difficult to be used in some complicated structures, due to their low flexibility and high brittleness. To solve this problem, this study prepared and investigated ceramic/polymer composites that can utilize a good flexibility of polymers. Polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) and 0.77(Bi1/2Na1/2)TiO3-0.23SrTiO3 (BNST23) ceramics were selected to fabricate the composites. Ceramic/polymer composites were prepared using various volume fractions of BNST23 ceramics. The distribution of piezoceramic particles in BNST23/PVDF-TrFE composites was investigated using optical microscopy (OM) and scanning electron microscopy (SEM). The dielectric and piezoelectric properties of the composites were significantly influenced by the volume fraction of the piezoelectric ceramics. As a result, the highest piezoelectric constant (d33) of 56 pC/N was obtained in a composites with 70% volume fraction of BNST23 ceramics. Accordingly, it is expected that BNST23/PVDF-TrFE composites can be applied to various sensor applications.

Enhanced Piezoelectric Properties of Lead-Free La and Nb Co-Modified Bi0.5(Na0.84K0.16)0.5TiO3-SrTiO3 Ceramics

  • Malik, Rizwan Ahmed;Hussain, Ali;Maqbool, Adnan;Zaman, Arif;Song, Tae Kwon;Kim, Won Jeong;Kim, Myong Ho
    • Korean Journal of Materials Research
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    • v.25 no.6
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    • pp.288-292
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    • 2015
  • New lead-free piezoelectric ceramics $0.96[\{Bi_{0.5}(Na_{0.84}K_{0.16})_{0.5}\}_{1-x}La_x(Ti_{1-y}Nb_y)O_3]-0.04SrTiO_3$ (BNKT-ST-LN, where $x=y=0.00{\leq}(x=y){\leq}0.015)$ were synthesized using the conventional solid-state reaction method. Their crystal structure, microstructure, and electrical properties were investigated as a function of the La and Nb (LN) content. The X-ray diffraction patterns revealed the formation of a single-phase perovskite structure for all the LN-modified BNKT-ST ceramics in this study. The temperature dependence of the dielectric curves showed that the maximum dielectric constant temperature ($T_m$) shifted towards lower temperatures and the curves became more diffuse with an increasing LN content. At the optimum composition (LN 0.005), a maximum value of remnant polarization ($33C/cm^2$) with a relatively low coercive field (22 kV/cm) and high piezoelectric constant (215 pC/N) was observed. These results indicate that the LN co-modified BNKT-ST ceramic system is a promising candidate for lead-free piezoelectric materials.

Effect of Sintering Time on the Piezoelectric Properties of (Na,K,Li)(Nb,Sb,Ta)O3 Ceramics ((Na,K,Li)(Nb,Sb,Ta)O3계 세라믹스의 소성시간이 압전특성에 미치는 영향)

  • Kim, Seung-Won;Yoo, Ju-Hyun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.30 no.4
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    • pp.218-222
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    • 2017
  • In this paper, in order to develop excellent composition ceramics for a piezoelectric energy- harvesting device, we synthesized $0.99(Na_{0.52}\;K_{0.443}\;Li_{0.037})(Nb_{0.883}\;Sb_{0.08}\;Ta_{0.037})O_3$ + $0.01(Sr_{0.95}Ca_{0.05})TiO_3$ + $0.3\;wt%\;Bi_2O_3\;+\;0.3\;wt%\;Fe_2O_3\;+\;0.3\;wt%\;CuO$ (abbreviated as NKN-SCT) ceramics with different sintering times, using the ordinary solid-state reaction method. The effect of sintering time on the microstructure and piezoelectric properties was investigated. The ceramics with the sintering time of 7 h have the optimum values of the piezoelectric constant ($d_{33}$), piezoelectric voltage constant ($g_{33}$), planar piezoelectric coupling coefficient (kp), mechanical quality factor (Qm), and dielectric constant (${\varepsilon}r$): $d_{33}=314[pC/N]$, $g_{33}=20.07[10^{-3}mV/N]$, kp = 0.442, Qm = 93, ${\varepsilon}r=1,768$, all being suitable for a piezoelectric energy-harvesting device.

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 La2O3 Doping on Phase Transition Behavior and Electromechanical Strain Properties in Bismuth-Based Lead-Free Piezoelectric Ceramics (비스무스계 무연 압전 세라믹스의 상전이 거동 및 전기 기계적 변형 특성에 대한 La2O3 도핑 효과 연구)

  • Eun Seo Kang;Sung Jae Hyoung;Yubin Kang;Min Sung Park;Trang An Duong;Jae-Shin Lee;Hyoung-Su Han
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.37 no.4
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    • pp.457-463
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    • 2024
  • (Bi1/2Na1/2)TiO3(BNT) piezoelectric ceramics are one of the promising materials that can replace Pb(Zr, Ti)O3(PZT) piezoelectric ceramics due to the high electromechanical strain properties. However, it is still difficult to use practical applications because the required electric field for inducing electromechanical strain is relatively higher than that of PZT ceramics. To overcome this problem, it has been intensively studied on doping impurity or modifying other ABO3 for BNT-based piezoelectric ceramics. Therefore, this study investigated the effects of La2O3 doping on the phase transition behavior and electromechanical strain properties in BNT-SrTiO3 (BNT-ST) lead-free piezoelectric ceramics. In the case of the temperature-dependent dielectric properties, it was confirmed that a phase transition from ferroelectrics to relaxors is induced with increasing La2O3 content. As a result, the electromechanical strain properties of BNT-ST ceramics were improved. The highest Smax/Emax value corresponding to 300 pm/V was obtained at 2 mol% La2O3-dopped BNT-ST ceramics. Accordingly, this study successfully demonstrated that La2O3 doping is effective on the inducing phase transition from ferroelectrics to relaxors and the improving electromechanical strain properties of BNT-ST lead-free piezoelectric ceramics.

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.

The Mineralogical and Geochemical Study on Korean Scheelites and its Application to the Ore Prospecting (한국산 灰重石鑛의 광물학적, 지화학적 연구 및 그의 探査에의 이용)

  • So, Chil-Sup;Park, Maeng-Eon
    • Economic and Environmental Geology
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    • v.12 no.2
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    • pp.79-93
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    • 1979
  • Twenty five samples of the scheelite-powellite series from twelve Korean tungsten deposits of various geologic settings were studied mineralogically and geochemically. Variations in the trace-element contents of the scheelite minerals are considered in relation to geologic settings and mineralogic properties. Scheelites from ore deposits developed in similar geologic settings and under similar physicochemical conditions are characterized by specific combinations of trace elements.

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