• Title/Summary/Keyword: coercive field

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Physical Properties and Out-put Characteristics of Piezoelectric Transformer of $Pb(Mg, Te, Mn, Nb)O_3-PZT$ Ceramics with Addition of $CeO_2$ ($CeO_2$을 첨가한 $Pb(Mg, Te, Mn, Nb)O_3-PZT$계 세라믹스의 물리적 성질과 압전트랜스의 출력특성)

  • 박순태;정수태;이종헌
    • Journal of the Korean Ceramic Society
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    • v.30 no.9
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    • pp.761-767
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    • 1993
  • Electrical and mechanical properties of Pb(Mg, Te, Mn, Nb)O3-PZT ceramics are investigated as a function of CeO2 addition (0 to 0.3wt%), and the output characteristics of piezoelectric transformer are also presented. The grain size decreased and the shapes of particles were more uniform with the addition of CeO2. The coercive electric field(9500V/cm), mechanical quality factor (2500) and bend strength (1065kg/$\textrm{cm}^2$) were improved by addition of CeO2 0.2wt%. After repetition of a number of stress cycles, the degradation of k33 was not found in this sample. The voltage step-up ratio (Vdc/Vrms) of piezoelectric ceramic transformer (half wavevoltage doubler, load resistor 100M.ohm) was about 950 in a linear region, its value was relatively higher than other materials.

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The Microstructure and Magnetic Properties of YIG Powders Synthesized by a Coprecipitaion and a Sonochemical Process

  • Hong, Seong-Min;Kim, Yong-Il;Kim, Cheol-Gi
    • Journal of Magnetics
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    • v.14 no.4
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    • pp.165-167
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    • 2009
  • Nano-sized Yttrium iron garnet (YIG;$Y_3Fe_5O_{12}$) particles have been synthesized by using coprecipitation and a heat treatment process. The YIG particles were made using a nitrate or a chloride salt solution. The pH concentration of the solution was fixed at 12. Spherical shaped YIG particles were made with a size of about 20 nm. The magnetization value of the particles was smaller than the bulk value but their coercive field showed a high value.

Characteristics of Ferroelectric Transistors with $BaMgF_4$ Dielectric

  • Lyu, Jong-Son;Jeong, Jin-Woo;Kim, Kwang-Ho;Kim, Bo-Woo;Yoo, Hyung-Joun
    • ETRI Journal
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    • v.20 no.2
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    • pp.241-249
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    • 1998
  • The structure and electrical characteristics of metal-ferroelectric-semiconductor FET(MFSFET) for a single transistor memory are presented. The MFSFET was comprised of polysilicon islands as source/drain electrodes and $BaMgF_4$ film as a gate dielectric. The polysilicon source and drain were built-up prior to the formation of the ferroelectric film to suppress a degradation of the film due to high thermal cycles. From the MFS capacitor, the remnant polarization and coercive field were measured to be about $0.6{\mu}C/cm^2$ and 100 kV/cm, respectively. The fabricated MFSFETs also showed good hysteretic I-V curves, while the current levels disperse probably due to film cracking or bad adhesion between the film and the Al electrode.

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Piezoelectric and Dielectric Characteristics of $NaKNbO_3$ ceramics according to the poling condition (분극조건에 따른 무연 $NaKNbO_3$ 세라믹스의 압전 및 유전 특성)

  • Lee, Sang-Ho;Yoo, Ju-Hyun;Lee, Kab-Soo
    • Proceedings of the KIEE Conference
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    • 2005.11a
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    • pp.157-159
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    • 2005
  • In this study, in order to develop Pb-free piezoelectric ceramics, $[Li_{0.04}(Na_{0.44}K_{0.52)-(Nb_{0.86}Ta_{0.10}Sb_{0.04})]O_3$ ceramics were fabricated by conventional mixed oxide method and their piezoelectric characteristics were investigated according to the poling condition. The transition temperature from orthorhombic phase to tetragonal phase observed at $93[^{\circ}C]$ and Curie temperature was $346[^{\circ}C]$. At $50[^{\circ}C]$ poling temperature, dielectric constant, electromecha nical coupling factor kp, piezoelectric $d_{33}$ const ant, coercive field Ec, remanant polarization Pr and mechanical quality factor Qm showed the optimum value of 737, 0.45, 209[pC/N], 1l.34[kV/cm], $7.14[{\mu}C/cm^2]$ and 205, respectively.

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Preparation and Characterization of Screen-printed Lead Zirconate Titanate Thick Films

  • Lee Sung-Gap
    • Transactions on Electrical and Electronic Materials
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    • v.7 no.2
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    • pp.72-75
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    • 2006
  • Ferroelectric PZT heterolayered thick films were fabricated by the alkoxide-based sol-gel method. PZT(Zr/Ti=60/40) paste was made and alternately screen-printed on the $Al_2O_3$ substrates. We have introduced a press-treatment to obtain a good densification of screen printed films. The porosity of the thick films was decreased with increasing the applied pressure and the thick films pressed at $0.6ton/cm^2$ showed the dense microstructure and thickness of about $76{\mu}m$. The relative dielectric constant increased with increasing the applied pressure. The remanent polarization and coercive field increased with increasing applied pressure and the values for the PZT thick films pressed at $0.6ton/cm^2$ were $16.6{\mu}C/cm^2$, 76.9 kV/cm, respectively.

Effect of Laser Pulse Repetition Rate on the Electrical Properties of $Pb(Zr_{0.48}Ti_{0.52})O_3$ (PZT) Thin Films grown by Pulsed Laser Deposition (펄스 레이저 증착법에 의해 제작된 Laser pulse repetition rate의 변화에 따른 $Pb(Zr_{0.48}Ti_{0.52})O_3$ (PZT) 박막의 전기적 특성)

  • Li, Dong-Hua;Lee, Sang-Yeol
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.11a
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    • pp.11-12
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    • 2005
  • [ $Pb(Zr_{0.48}Ti_{0.52})O_3$ ] (PZT) thin films were deposited on Pt(111)/Ti/$SiO_2$/Si substrates by pulsed laser deposition. In order to study the effect of different laser pulse repetition rate on the dielectric and ferroelectric properties of PZT thin films,2 Hz and 5 Hz of laser pulse repetition rate were selected. We compared the results of XRD pattern, dielectric constant and hysteresis characteristics. From the experimental data, we found that the electrical properties of PZT thin films which grown ar 2 Hz of laser pulse repetition rate were better than those which grown at 5 Hz of laser pulse repetition rate.

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Effect of $Y^{3+}$ Impurity Addition on the Structural and Electrical Properties of PZT (65/35) Thin Film ($Y^{3+}$ 불순물 첨가가 PZT (65/35) 박막의 구조적, 전기적 특성에 미치는 영향)

  • 이규선;김준한;윤현상;이두희;박창엽
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1994.11a
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    • pp.24-27
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    • 1994
  • Variations with structural and electrical properties of Yttrium added PZT thin films were observed and measured respectively. Area of rosette was increased by Yttrium added and shapes of hysteresis curves were changed to slim type. $Y^{3+}$ ion substituted $Pb^{2+}$ ion and played the role of doner. Because the creation of space charges was restricted by Yttrium, degradation of remanent polarizations by cumutation of polarization reversals of PZT was protected. But coercive field was increased because of vacancies generated Yttrium added.

Chemical Solution Deposition 방법으로 증착된 $Bi_{0.8}A_{0.2}FeO_3$ (A=Pb, Co) 박막의 자기적 특성에 대한 연구

  • Cha, Jeong-Ok;An, Jeong-Seon
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.08a
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    • pp.245-245
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    • 2011
  • $BiFeO_3$ (BFO)박막에 전위금속 Pb와 Co를 각각 치환환 박막을 chemical solution deposition 방법으로 Pt/Ti/SiO2/Si(100) 기판위에 증착하였다. Bi 자리에 Pb와 Co를 20 at.% 치환하였으며, 치환된 $Bi_{0.8}Pb_{0.2}FeO_3$ (BPFO), $Bi_{0.8}Co_{0.2}FeO_3$ (BCFO) 박막의 구조적, 자기적 특성 변화를 BFO 박막과 비교하여 조사하였다. XRD 패턴을 분석한 결과 BPFO, BCFO 박막들은 모두 rhombohedrally distorted perovskite 구조였으며 불순물인 pyrochlore 상이 약하게 관측되었다. 치환이 이루어진 BPFO, BCFO 박막들의 자기 이력곡선은 안정된 포화곡선을 나타냈으며 BFO의 포화값(5 emu/$cm^3$)에 비해 크게 증가된 55 emu/$cm^3$, 35 emu/$cm^3$의 값을 나타냈다. 또한 보자력장(coercive field, Hc)값도 BFO의 500 Oe보다 크게 증가된 1,200 Oe, 800 Oe의 값을 보였다.

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Electrical and Optical Characteristics of X/40/60 PLZT Thin Films by Sol-Gel Processing (Sol-Gel 법에 의한 X/40/60 PLZT 박막의 전기 및 광학 특성)

  • 이진욱;마석범;강종윤;장낙원;박정흠
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1996.11a
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    • pp.139-142
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    • 1996
  • X/40/60 PLZT thin films were prepared by sol-gel processing and annealed by rapid thermal annealing(RTA). X/40/60 PLZT thin films were crystallized at 75$0^{\circ}C$ for 5min by RTA. Hysteresis curves were narrowed and coercive field was decreased from 50kV/cm to 31.2 kV/cm and remnant polarization was also decreased from 14.3$\mu$C/$\textrm{cm}^2$ to 6.72$\mu$C/$\textrm{cm}^2$ as La mol% increased. Dielectric constanat and optical transmittance were increased with increasing La mol%.

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The Dielectric Properties of BaTi $O_3$ by Additive Material (첨가제에 의한 BaTi $O_3$의 유전특성)

  • 홍경진;정우성;민용기;김태성
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1996.11a
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    • pp.413-416
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    • 1996
  • The ceramic dielectrics were fabricated by mixing of Mn $O_2$ and ZnO at (B $a_{0.85}$ $Ca_{0.15}$)Ti $O_3$ and studied for dielectric relaxation characteristics. The dielectric relaxation time was increased by space charge polarization of palaelectric layer at the low temperature and frequency but it was decreased by Interface polarization at the high temperature and frequency. The remnant polarization and coercive field of ceramic dielectrics was decreased by rising temperature.ure.

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