• 제목/요약/키워드: $Bi_2O_2CO_3$

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Eu와 V 동시 도핑에 의한 BiFeO3 박막의 구조와 전기적 특성 (Structural and Electrical Properties of BiFeO3 Thin Films by Eu and V Co-Doping)

  • 장성근;김윤장
    • 한국전기전자재료학회논문지
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    • 제32권3호
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    • pp.229-233
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    • 2019
  • Pure $BiFeO_3$ (BFO) and (Eu, V) co-doped $Bi_{0.9}Eu_{0.1}Fe_{0.975}V_{0.025}O_{3+{\delta}}$ (BEFVO) thin films were deposited on $Pt(111)/Ti/SiO_2/Si(100)$ substrates by chemical solution deposition. The effects of co-doping were observed by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy (SEM). The electrical properties of the BEFVO thin film were improved as compared to those of the pure BFO thin film. The remnant polarization ($2P_r$) of the BEFVO thin film was approximately $26{\mu}C/cm^2$ at a maximum electric field of 1,190 kV/cm with a frequency of 1 kHz. The leakage current density of the co-doped BEFVO thin film ($4.81{\times}10^{-5}A/cm^2$ at 100 kV/cm) was two orders of magnitude lower than of that of the pure BFO thin film.

ZnO-Zn2BiVO6-Co3O4 세라믹스의 액상소결과 전기적 특성 (Liquid Phase Sintering and Electrical Properties of ZnO-Zn2BiVO6-Co3O4 Ceramics)

  • 홍연우;김유비;백종후;조정호;정영훈;윤지선;박운익
    • 한국전기전자재료학회논문지
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    • 제30권2호
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    • pp.74-80
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    • 2017
  • This study focuses on the effects of doping $Zn_2BiVO_6$ and $Co_3O_4$ on the sintering and electrical properties of ZnO; where, ZZ consists of 0.5 mol% $Zn_2BiVO_6$ in ZnO, and ZZCo consists of 1/3 mol% $Co_3O_4$ in ZZ. As ZnO was sintered at about $800^{\circ}C$, the liquid phases, which are composed of $Zn_2BiVO_6$ and $Zn_2BiVO_6$-rich phases, were found to be segregated at the grain boundaries of sintered ZZ and ZZCo, respectively, which demonstrates that $V_o^{\cdot}$(0.33~0.36 eV) are formed as dominant defects according to the analysis of admittance spectroscopy. As $Co_3O_4$ is doped to ZZ, the resistivity of ZnO decreases to ~38%, while donor density ($N_d$), interface state density ($N_t$), and barrier height (${\Phi}_b$) increase twice higher than those of ZZ, according to C-V characteristics. This result harbingers that ZZCo and its derivative compositions will open the gate for ZnO to be applied as more progressive varistors in the future, as well as the advantageous opportunity of manufacturing ZnO chip varistors at lower sintering temperatures below $900^{\circ}C$.

$BiNbO_4$세라믹스의 유전 특성과 미세구조에 관한 연구 (Microwave Dielectric Properties and Microstructure of $BiNbO_4$ Ceramics)

  • 고상기;김현학;김경용
    • 한국전기전자재료학회논문지
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    • 제11권3호
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    • pp.208-213
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    • 1998
  • Microwave dielectric properties of $BiNbO_4$ containing CuO and $V_2O_5$(BN ceramics). BN ceramic with 0.07wt% $V_2O_5$ and 0.03wt% CuO (BNC3V7) was sintered at $900^{\circ}C$ where it is possible for these to be co-fired with Ag electrode. The dielectric constant of 44.3, TCF (Temperature Coefficient of resonance Frequency) of 2 ppm/$^{\circ}$ and Q${\times}f_o$ value (product of Quality value and resonance Frequency) of 22,000GHz could be obtained from those ceramics. It is observed that orthorhombic structure was stable $1000^{\circ}C$. As sintering temperature increases, the dielectric properties decreased. The main reasons were abnormal grain growth and the main peak of triclinic moved from the main peak of orthorhombic.

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Aerosol Synthesis of Gd2O3:Eu/Bi Nanophosphor for Preparation of Photofunctional Pearl Pigment as Security Material

  • Jung, Kyeong Youl;Han, Jang Hoon;Kim, Dae Sung;Choi, Byung-Ki;Kang, Wkang-Jung
    • 한국세라믹학회지
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    • 제55권5호
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    • pp.461-472
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    • 2018
  • $Gd_2O_3:Eu/Bi$ nanoparticles were synthesized via spray pyrolysis and applied for the preparation of a luminescent pearl pigment as an anti-counterfeiting material. The luminescence properties were optimized by changing the $Eu^{3+}$ and $Bi^{3+}$ concentration. Ethylene glycol was used as an organic additive to prepare the $Gd_2O_3:Eu/Bi$ nanoparticles. The highest emission intensity was achieved when the total dopant content was 10.0 at.% and the mole fraction of Bi was 0.1. The concentration quenching was mainly due to dipole-dipole interactions between the same activators, and the critical distances were 9.0 and $19.6{\AA}$ for $Eu^{3+}$ and $Bi^{3+}$, respectively. The prepared $Gd_2O_3:Eu/Bi$ powder exhibited an average size of approximately 82.5 nm and a narrow size distribution. Finally, the $Gd_2O_3:Eu/Bi$ nanophosphor coated on the surface of the pearl pigment was confirmed to have good red emission under irradiation from a portable ultraviolet light-emitting diode lamp (365 nm).

ZnO-Bi2O3-Mn3O4-Co3O4 바리스터의 결함과 전기적 특성 (Defects and Electrical Properties of ZnO-Bi2O3-Mn3O4-Co3O4 Varistor)

  • 홍연우;이영진;김세기;김진호
    • 한국전기전자재료학회논문지
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    • 제25권12호
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    • pp.961-968
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    • 2012
  • In this study, we have investigated the effects of Mn and Co co-doping on defects, J-E curves and grain boundary characteristics of ZnO-$Bi_2O_3$ (ZB) varistor. Admittance spectra and dielectric functions show two bulk defects of $Zn_i^{{\cdot}{\cdot}}$ (0.17~0.18 eV) and $V_o^{\cdot}$ (0.30~0.33 eV). From J-E characteristics the nonlinear coefficient (${\alpha}$) and resistivity (${\rho}_{gb}$) of pre-breakdown region decreased as 30 to 24 and 5.1 to 0.08 $G{\Omega}cm$ with sintering temperature, respectively. The double Schottky barrier of grain boundaries in ZB(MCo) ($ZnO-Bi_2O_3-Mn_3O_4-Co_3O_4$) could be electrochemically single type. However, its thermal stability was slightly disturbed by ambient oxygen because the apparent activation energy of grain boundaries was changed from 0.64 eV at lower temperature to 1.06 eV at higher temperature. It was revealed that a co-doping of Mn and Co in ZB reduced the heterogeneity of the barrier in grain boundaries and stabilized the barrier against an ambient temperature (${\alpha}$-factor= 0.136).

$Sb_2O_3$함량 변화에 따른 저전압용 ZnO Varistor의 미세구조 특성 (Microstructure Properties of Zinc Oxide Varistor with $Sb_2O_3$ Contents for Low Voltage Application)

  • 박종주;서정선
    • 한국결정학회지
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    • 제8권2호
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    • pp.149-153
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    • 1997
  • 본 연구는 ZnO-Bi2O3-Co3O4-MnCo3-Cr2O3-Sb2O3를 기본 조성으로 하여 Sb2O3 첨가량(0-0.09mol%) 변화에 따른 grain size와 미세구조 특성을 고찰하고자 하였다. Sb2O3가 첨가되지 않은 조성은 이상 입자 성장에 의해 거대한 ZnO grain이 생성되었으며, Sb2O3를 첨가한 조성은 Zn7Sb2O12 spinel상 생성으로 입자 성장이 억제되어 이상입자 성장이 관찰되지 않았다. Sb2O3 첨가량 증가에 따라 ZnO grain size가 현격하게 감소하였으며 그 미세구조는 조밀하고 균일한 크기의 grain분포를 나타내었다.

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Phase Transformation Behavior of Bi2O3-ZnO-Nb2O5 Ceramics sintered at low Temperature

  • Shiao, Fu-Thang;Ke, Han-Chou;Lee, Ying-Chieh
    • 한국분말야금학회:학술대회논문집
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    • 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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    • pp.1232-1233
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    • 2006
  • To co-fire with commercial LTCC (Low Temperature Co-fired Ceramic) materials at $850^{\circ}C{\sim}880^{\circ}C$, different contents of $B_2O_3$ were added to the $Bi_2O_3-ZnO-Nb_2O_5$ (BZN) ceramics. According to the test results, the cubic phase of BZN was transformed into orthorhombic in all the test materials. $BiNbO_4$ phase was formed in test materials with $2{\sim}5wt%$ of $B_2O_3$ addition. The phase transformation of cubic BZN was controlled during the synthesis process with excess ZnO content. The Cubic and orthorhombic phases of BZN could coexist and be sintered densely at $850^{\circ}C/2hr$.

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Role of the $Bi_2O_3\;in\;SrBi_2TaNbO_9/Bi_2O_3/SrBi_2TaNbO_9$ Heterostructure and Low Temperature Annealing Property

  • Park, Yoon-Beak;Jang, Se-Myeong;Kim, Ju-Hyung;Lee, Jeon-Kook;Park, Jong-Wan
    • The Korean Journal of Ceramics
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    • 제6권3호
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    • pp.276-279
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    • 2000
  • Ferroelectric properties of $SrBi_2TaNbO_9$ (SBTN) thin films were changed by the amount of Bi content in SBTN. We suggested that the addition of excess Bi into the films could be accomplished by heat-treating $SBTN/Bi_2O_3/SBTN$ heterostructure fabricated by r.f. magnetron sputtering method. Excess Bi composition was controlled by the thickness of the sandwiched $Bi_2O_3$ from 0 to $400\;\AA$. When the SBTN thin films were inserted by $400\;{\AA}\;Bi_2O_3$ layer, $Bi_2Pt$ phase was formed as a second phase in SBTN films, resulting in poor ferroelectric properties. The onset temperature for hysteresis loop can be reduced by heat treating $SBTN/Bi_2O_3/SBTN$ heterostructure. The films with $SBTN/Bi_2O_3(100\;{\AA})/SBTN$ hetero-structure followed by annealing at $650^{\circ}C$ for 30 min show 2Pr and Ec of $5.66\;{\mu}C/\textrm{cm}^2$ and 54 kV/cm, respectively.

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BiFeO3 치환에 따른 PMW-PNN-PZT세라믹스의 강유전 및 압전 특성 (Ferroelectric and Piezoelectric Properties of PMW-PNN-PZT Ceramics as a Function of BiFeO3 Substitution)

  • 라철민;류주현
    • 한국전기전자재료학회논문지
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    • 제28권9호
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    • pp.577-580
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    • 2015
  • In this paper, in order to develop the composition ceramics with the outstanding piezoelectric properties, $Pb(Mg_{1/2}W_{1/2})_{0.03}(Ni_{1/3}Nb_{2/3})_{0.09}(Zr_{0.5}Ti_{0.5})_{0.88}O_3$ ceramics substituted with $BiFeO_3$ were prepared by the conventional solid-state reaction method. The addition of small amount of $Li_2CO_3$ and $CaCO_3$ as sintering aids decreased the sintering temperature of the ceramics. The effects of $BiFeO_3$ substitution on their piezoelectric and dielectric properties were investigated. when 0.015 mol $BiFeO_3$ was substituted, the optimal physical properties of $d_{33}=590pC/N$, $E_c=8.78kV/mm$ were obtained.

Bi-electrolyte Carbon Dioxide Gas Sensor Based on Paste Sodium-Beta Alumina and Yttria-stabilized Zirconia

  • Han, Hyeuk Jin;Park, Chong Ook
    • 센서학회지
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    • 제23권3호
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    • pp.170-172
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    • 2014
  • $CO_2$ sensor was used only one solid electrolyte in many cases. To improve the sensing characteristics of $CO_2$ sensors, solid electrolyte $CO_2$ sensor has been developed by bi-electrolyte type sensor using Na-Beta-alumina and YSZ. However, in many further studies, bi-electrolyte type sensor was made by pellet pressed by press machine and additional treatment for formation of interface. In the aspect of mass production, using thick film and additional treatment is not suitable. In this study, $CO_2$ sensor was fabricated by bi-electrolyte structure which was made by an NBA paste layer deposited on YSZ pellet and fired at $1650^{\circ}C$ for 2 hour. The formation of stable interface between YSZ and NBA were confirmed by SEM image. When the type IV electrochemical cell arrangement represented by $CO_2,O_2,Pt{\mid}Li_2CO_3-CaCO_3{\parallel}NBA{\parallel}YSZ{\mid}O_2,Pt$ is used to measure the $CO_2$ concentration in air. This sensor EMF should depend only on the concentration of $CO_2$ by logarithmic. Also, sensor shows $P_{CO_2}$ and EMF relationship like nerstian reaction at a temperature of $450^{\circ}C$.