• Title/Summary/Keyword: $BaTiO_{3}$

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Piezoelectric properties of (1-x)(Na,K)$NbO_3$-xBa(Zr,Ti)$O_3$ ceramics with composition (조성비에 따른 (1-x)(Na,K)$NbO_3$-xBa(Zr,Ti)$O_3$ 세라믹스의 압전 특성)

  • Lee, Young-Hie;Lee, Dong-Hyun;Bae, Seon-Gi;Lee, Sang-Chul;Choi, Dal-Hae
    • Proceedings of the KIEE Conference
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    • 2011.07a
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    • pp.1436-1437
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    • 2011
  • (1-x)(Na,K)$NbO_3$-xBa(Zr,Ti)$O_3$ lead free piezoelectric ceramics were synthesized to enhance the piezoelectric properties of (Na,K)$NbO_3$. The synthesis and sintering method were the conventional solid state reaction method and general sintering method in air atmosphere. We report the improved piezoelectric properties in the perovskite structure composed of the NKN and BZT ceramics. We investigated the effects of NKN, BZT on the structural and electrical properties of the NKN-BZT ceramics. The NKN-BZT ceramics show good performance with piezoelectric constant $d_{33}$=155pC/N. The results reveal that (1-x)(Na,K)$NbO_3$-xBa(Zr,Ti)$O_3$ ceramics are promising candidate materials for lead-free piezoelectric application.

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Effect of Heat Treatments on the PTCR of $BaTiO_3$ Ceramics Doped by $Nb^{+5}$ ($Nb^{+5}$ Doped $BaTiO_3$ 계에서 열처리가 PTCR 현상에 미치는 영향)

  • 문영우;정형진;윤상옥
    • Journal of the Korean Ceramic Society
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    • v.22 no.5
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    • pp.54-60
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    • 1985
  • This study is concerned with the mechanism of PTCR in $BaTiO_3$ ceramics doped by $Nb^{+5}$ Since the vacancy compensation layer at the grain boundary of n-type doped $BaTiO_3$ ceramics has been known as a major factor for surface state to give PTCR phenomena the dependence of PTCR on such vacancy compensation layer was attemped to be confirmed experimentally in this study. For the experiment quenching and annealing at various temperature after sintering were adopted to induce difference in the thickness of vacancycompensation layer so as to exihibit difference of PTCReffect eachother. The TEX>$Ba^{++}$ cocentration at the grain and grain boundary was measured by EDAX to confirm the formation of the vacancy compensation layer. It was found that i)either decrease in the temperature for quenching ii) or increase in the temperature for annealing improves the PTCR effect clearly iii)increase in TEX>$Ba^{++}$ concentration at the grain boundary results in the improvement of PTCR effect. It was concluded that all the experimental results gave the evidence for the dependence of PTCR effect on the vacancy compensation layer at the grain boundary which had been induced possibly by the $Ba^{++}$ diffusion by the heat treatment conducted.

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Structural and Electrical Properties of (Ba,Sr,Ca)TiO3 Thick Films doped with Dy 2O3 (Dy2O3를 첨가한 (Ba,Sr,Ca)TiO3 후막의 구조 및 전기적 특성 연구)

  • Noh, Hyun-Ji;Park, Sang-Man;Yun, Sang-Eun;Lee, Sung-Gap
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.20 no.8
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    • pp.680-684
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    • 2007
  • In this study, we investigated the effects of structural and electrical properties of $(Ba_{0.6},\;Sr_{0.3},\;Ca_{0.1})TiO_3$ thick films with variation $Dy_2O_3$ contents. $(Ba_{0.6},\;Sr_{0.3},\;Ca_{0.1})TiO_3$ powders, prepared by the sol-gel method, were mixed organic vehicle. The BSCT thick films doped with 0.1, 0.3, 0.5, 0.7 mol% $Dy_2O_3$ were fabricated by the screen-printing techniques on the alumina substrates and the structural and dielectric properties were investigated with variation of $Dy_2O_3$ doping contents. All BSCT thick films were sintered at $1420^{\circ}C$, for 2hr. In the TG-DTA analysis, the formation of the polycrystalline perovskite phase was observed at around $670 ^{\circ}C$. In the XRD analysis, all BSCT thick films showed the cubic perovskite structure. The average thickness of BSCT thick films was approximately $65{\mu}m$. The Curie temperature decreased with increasing $Dy_2O_3$ amount. The relative dielectric constant and dielectric loss of BSCT thick films doped with $Dy_2O_3$ 0.1 mol% were 6267 and 2.6 %, respectively.

Role of the Strain Energy in Diffuse Phase Transition of (Pb, Ba)(Zr, Ti)O3 ((Pb, Ba) (Zr, Ti)O3계의 확산된 상전이에 있어서 Strain Energy의 역할)

  • 이재찬;주웅길
    • Journal of the Korean Ceramic Society
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    • v.24 no.6
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    • pp.586-592
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    • 1987
  • The role of the strain energy and phase stability in the diffuse phase transition have been investigated in the highly disordered solid solution, (Pb1-xBax)(Zr0.4Ti0.6)O3 (0.2 x 0.4). X-ray diffraction analysis indicates that tetragonality (c/a) decreases with the increasing Ba content. Also as the Ba content increases, phase transition becomes more diffuse and at the same time dielectric relaxation as a function of measured frequencies in the 1KHz-10MHz range occurs very pronouncedly. In the Ba content range, 0.2 x 0.35, hysteresis loops are routinely observed and the loop is observed to narrow shape as the Ba content increases but becomes very slim at 40mol% Ba content. Moreover thermal analysis shows that there is no abrupt change in the thermal expansion coefficient below the apparent transition temperature at which dielectric constant becomes maximum. From the above results, it has been concluded that creation of the strain energy due to the distorthion that occurred during the phase transition suppresses diffuse phase transition.

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Growth and dielectric Properties or $BaTiO_3/SrTiO_3$ oxide artificial superlattice deposited by pulsed laser deposition (PLD) (Pulsed laser depostion (PLD)법으로 증착된 $BaTiO_3/SrTiO_3$ 산화물 초격자의 성장 및 유전특성)

  • 김주호;김이준;정동근;김용성;이재찬
    • Journal of the Korean Vacuum Society
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    • v.11 no.3
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    • pp.166-170
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    • 2002
  • Artificial $BaTiO_3$(BTO)/$SrTiO_3$(STO) oxide superlattice have been deposited on MgO (100) single crystal substrate by pulsed laser deposition(PLD) method. The stacking periodicity of BTO/STO superlattice structure was varied from $BTO_{1\;unit\; cell}/STO_{1\;unit\; cell}$ to $BTO_{125\;unit\; cell}/STO_{125 \;unit \;cell}$ thickness with the total thickness of 100 nm. The result of X-ray diffraction showed the characteristics of superlattice in the BTO/STO multilayer structure. we have also confirmed that there was no interdiffusion at the interface between BTO and STO layers by high resolution transmission electron microscopy(HRTEM). The dielectric constant of superlattice increased with decreasing stacking periodicity of the BTO/STO superlattice within the critical thickness. The dielectric constant of the BTO/STO superlattice reached a maximum i.e., 1230 at a stacking perioicity of $BTO_{2\;unit\; cell}/STO_{2\;unit\; cell}$ .

A Study on the Piezoelectric Properties of the Pb($Zn_{1/3}Nb_{2/3})O_3-Ba(Zn_{1/3}Nb_{2/3})O_3-PbTiO_3$ (Pb($Zn_{1/3}Nb_{2/3})O_3-Ba(Zn_{1/3}Nb_{2/3})O_3-PbTiO_3$ 세라믹의 압전특성에 관한 연구)

  • 박혜옥;박인길;이성갑;이영희
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1989.06a
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    • pp.70-73
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    • 1989
  • (1-x-y)Pb($Zn_{1/3}Nb_{2/3})O_3-Ba(Zn_{1/3}Nb_{2/3})O_3-PbTiO_3(0.12{\leq}x{\leq}0.21, 0.24{\leq}y{\leq}0.33$) ternary compound ceramics were fabricated by the mixed oxide method. The sintering temperature and time were 1050 [$^{\circ}C$], 2[hr]. Morphotropic phase boundary region was chosen for the composition. 0.55 PZN-0.21 BZN-0.24 PT specimen had the highest value of relative dielectric constants, 5353. The curie temperature of specimens were increased linearly with PT content. Near the morphotropic phase boundary, electro-mechanical coupoling factor and mechanical quality factor of the specimens had the highest values.

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$CaSnO_3$와 소결조제가 첨가된 $BaTiO_3$ 유전체 세라믹의 소결거동 및 유전특성

  • Kim, Tae-Hong;Lee, Jae-Shin;Choy, Tae-Goo
    • ETRI Journal
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    • v.13 no.2
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    • pp.42-53
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    • 1991
  • 고유전율 적충세라믹 커패시터 소재인 $BaTiO_3$ 자기물은 일반적으로 큐리오도인 약 $120^{\circ}C$부근에서 유전율이 최고 약 10,000정도로 증가한 다음 급격히 감소하므로 적절한 이동체를 첨가하여 큐리온도를 상온으로 이동시켜 상온에서 최대 유전율을 이용하여야 한다. 그리고$BaTiO_3$ 자기물은 $1300^{\circ}C$이상의 고온소결시 고가인 Pd전극이 요구된다. 그러나 자기물의 소결온도를 저온화화면 저가의 Ag합금으로 전극재료를 대체할 수 있다. 본 연구에서는 이동제로서 $CaSnO_3$ 를 이용하여 큐리온도를 상온으로 이동시켰다. 또한 소결온도를 저온화하기 위하여 $BaTiO_3$ 세라믹에 여러가지 산화물을 첨가하여 소결현상을 살펴보았다. 실험결과 첨가제를 넣지 않은 경우 소결온도는 $1350^{\circ}C$의 고온이 필요한 반면, $CuO,B_2O_3$$1050^{\circ}C$의 낮은 온도에서도 치밀화와 입도성장이 잘 일어났다. 특히 $B_2$$O_3$ 를 첨가한 경우는 $1250^{\circ}C$이상에서 소결할 때 절연저항이 낮아 유전손실이 큰 문제점을 보였지만, 최대 유전율이 11,000 정도로 높고, 양호한 유전율의 온도변화 특성을 나타내어 우수한 고유전율 소재의 첨가제로 응용될 가능성을 보였다

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Properties of Phosphate Glasses - $BaO-Nd_{2}O_3-TiO_2$ Ceramic Composites for Using Dielectric Materials Having Low Temperature Cofired Ceramic(LTCC) (저온동시소성 유전체 재료용 인산염계 유리-$BaO-Nd_{2}O_3-TiO_2$계 세라믹 복합체의 특성)

  • Lee Hoi Kwan;Lee Yong Su;Hwang Sheng-Jian;Kang Won Ho;Kim Hyung Sun
    • Journal of the Microelectronics and Packaging Society
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    • v.11 no.2 s.31
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    • pp.17-22
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    • 2004
  • In this study, BNT($BaO-Nd_{2}O_3-TiO_2$) and $70P_{2}O_5-5B_{2}O_3-(25-x)BaO-xNa_{2}O$ glass-ceramic composites were fabricated and investigated in order to apply for low temperature cofired ceramic. The prepared BNT based glass-ceramic composites were sintered at $800{\sim}950^{\circ}C$ with the glass fit contents ranging from 10 to $15\;wt\%$. The properties such as sintering and dielectric property were investigated in the ceramic compositions according to the phosphate glass frit. The dielectric constant was varied between 10 to 40 and shrinkage rate was increased according to increasing glass frit.

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Effect of La3+ and Ti4+ Ions on the Magnetic Properties of Barium Hexaferrite Powders Synthesized Using Sol-Gel Method

  • Ertus, Emre Burak;Yildirim, Serdar;Celik, Erdal
    • Journal of Magnetics
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    • v.21 no.4
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    • pp.496-502
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    • 2016
  • Doped and undoped barium hexaferrite powders ($BaFe_{12}O_{19}$, $Ba_{0.7}Ti_{0.3}Fe_{12}O_{19}$ and $Ba_{0.7}La_{0.3}Fe_{12}O_{19}$) were produced by the sol-gel method. The effects of substituting elements were studied in terms of the magnetic properties of barium hexaferrite powders. The magnetic properties were remarkably changed by the substitution of $La^{3+}$ and $Ti^{4+}$ ions for the $Ba^{2+}$ ion and were accompanied by oxygen deficiency in the $BaFe_{12}O_{19}$. Coercivities ($H_C$) from 4200 to 5100 Oe, remanences ($M_R$) from 22 to 49 emu/g and saturation magnetizations ($M_S$) from 41 to 73 emu/g were obtained for different samples. The obtained results were discussed in detail.