• 제목/요약/키워드: $Bi_{0.5}K_{0.5}TiO_3$

검색결과 158건 처리시간 0.03초

Fabrication and Characterization of (1-x)BiFeO3-xBaTiO3 Ceramics Prepared by a Solid State Reaction Method

  • Chandarak, S.;Unruan, M.;Sareein, T.;Ngamjarurojana, A.;Maensiri, S.;Laoratanakul, P.;Ananta, S.;Yimnirun, R.
    • Journal of Magnetics
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    • 제14권3호
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    • pp.120-123
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    • 2009
  • In this study, BiFe$O_3$-BaTi$O_3$ ceramics have been fabricated by a solid-state reaction method. The effects of BaTi$O_3$ content in the (1-x)BiFe$O_3$-xBaTi$O_3$ (x = 0.1, 0.2, 0.25, 0.3, 0.4, 0.5) system on crystal structure and magnetic, dielectric, and ferroelectric properties were investigated. Perovskite BiFe$O_3$ was stabilized through the formation of a solid solution with BaTi$O_3$. Rhombohedrally distorted structure (1-x)BiFe$O_3$-xBaTi$O_3$ ceramics showed strong ferromagnetism at x = 0.5. Dielectric and ferroelectric properties of the BiFe$O_3$-BaTi$O_3$ system also changed significantly upon addition of BaTi$O_3$. It was found that the maximum dielectric and ferroelectric properties were exhibited in the (1-x)BiFe$O_3$-xBaTi$O_3$ system at x = 0.25. This suggested the morphotropic phase boundary (MPB) with the coexistence of both rhombohedral and cubic phases of the (1-x)BiFe$O_3$-xBaTi$O_3$ system at x = 0.25.

비납계 (Bi0.5Na0.5)TiO3-(Bi0.5K0.5)TiO3 세라믹의 유전 및 압전 특성 (Dielectric and Piezoelectric Properties of Lead-free (Bi0.5Na0.5)TiO3-(Bi0.5K0.5)TiO3 Ceramics)

  • 조정아;국민호;성연수;이수호;송태권;정순종;송재성;김명호
    • 한국재료학회지
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    • 제15권10호
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    • pp.639-643
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    • 2005
  • Lead-free $[Bi_{0.5}(Na_{1-x}K_x)_{0.5}TiO_3](x=0\~1.0)$ ceramics were prepared using a solid state reaction method and their structural and electrical characteristics were investigated. X-ray investigations indicated that the rhombohedral-tetragonal morphotropic phase boundary(MPB) of the $[Bi_{0.5}(Na_{1-x}K_x)TiO_3$ ceramics exists in the range of $x=0.16\~0.20$. The optimum values of piezoelectric constant$(d_{33})$, dielectric constant, and electromechanical coupling factor $(k_p)$ were obtained at $x=0.16\~0.20$ of the MPB region.

$BaTiO_3$ - $(Bi_{0.5}Ko_{0.5})TiO_3$계 세라믹의 PTC효과와 미세구조 (Microstructure and PTCR Behavior of Semiconducting (1-x)$BaTiO_3$ - x$(Bi_{1/2}K_{1/2})TiO_3$ Ceramics)

  • 박용준;정영훈;이영진;백종후;김대준;이우영
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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    • pp.336-336
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    • 2008
  • A positive temperature coefficient of electrical resistivity (PTCR) was investigated in a ferroelectric lead-free perovskite-type compound $(Bi_{0.5}K_{0.5})TiO_3$ within $BaTiO_3$-based solid solution ceramics. The electrical properties and the microstructure of (1-x) $BaTiO_3$ - x $(Bi_{0.5}K_{0.5})TiO_3$ (BBKT) ceramics made using a conventional mixed and have been synthesized by an ordinary sintering technique. The Curie temperature was obviously increased with increasing of $(Bi_{0.5}K_{0.5})TiO_3$ content. The BKT ceramics (x=0.05) sintered at $1400^{\circ}C$ for 4h display low resistivity values of $10^1-10^2$ ohm cm at room temperature, PTCR effect(jump) of 1.05*$10^3$, and the Curie temperature of $T_c=141^{\circ}C$.

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Ar/$O_2$비에 따른 (Bi,Ba,Sr)$TiO_3$[BBST] 박막의 구조적 특성 (The structural properties of the (Bi,Ba,Sr)$TiO_3$[BBST] thin films with Ar/$O_2$ rates)

  • 김정태;이상철;이성갑;배선기;이영희
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2002년도 하계학술대회 논문집 C
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    • pp.1488-1490
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    • 2002
  • The (Bi,Ba,Sr)$TiO_3$[BBST] thin films were fabricated on Pt/Ti/$SiO_2$/Si substrate by RF sputtering method. We investigated the effects of Ar/$O_2$ rates on the structural properties of BBST thin films. Decreasing the $O_2$ rates, the intensity of $BaBi_4Ti_4O_{15}$ and $Bi_4Ti_3O_{12}$ peaks were increased but the $(Ba_{0.5}Sr_{0.5})TiO_3$ peak was decreased. In the case of BBST thin films deposited with condition of 90/10 (Ar/$O_2$) ratio, the composition of Ba/Sr/Bi was 0.35/0.4/0.25. Also, in the BBST thin films deposited with condition of 80/20(Ar/$O_2$) ratio, the composition of Br,Sr and Ti were relatively uniform. But the component of Bi and Ti were diffused into the Pt layers.

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Bi 가 치환된 BaO.$Nd_{2}O_{3}$.$4TiO_{2}$ 세라믹스의 마이트로파 유전특성 (Microwave Dielectric Properties in Bi-Substituted BaO.$Nd_{2}O_{3}$.$4TiO_{2}$)

  • 천재일;김정석
    • 한국재료학회지
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    • 제8권7호
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    • pp.659-663
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    • 1998
  • BaO.$Nd_{2}O_{3}$.$4TiO_{2}$세라믹스에서 Bi 치환위치 및 Bi 치환 량에 따른 상, 미세구조, 마이크로파 유전특성 등을 조사하였다. BaO.$Nd_{2}O_{3}$.$4TiO_{2}$ 세라믹스의 Nd 치환되어 $BaO.(Nd_{1-x}Bi_x)_2O_3.4TiO_2$고용체 (0$\leq$x$\leq$0.2)를 형성하였다. $BaO.(Nd_{1-x}Bi_x)_2O_3.4TiO_2$에서 Bi 치환 량이 x=0에서 x=0.2까지 증가됨에 따라 입자크기가 계속 증가하였으며, 유전상수는 84에서 108까지 계속 증가하였고, 공진 주파수의 온도계수는 $44 ppm^{\circ}C$에서 $-30ppm^{\circ}C$로 계속 감소하였다. $BaO.(Nd_{1-x}Bi_x)_2O_3.4TiO_2$조성에서 Bi 치환 량이 x=0.04에서 0.08사이일 때 가장 양호한 마이크로파 유전특성이 얻어졌으며 이 때의 유전상수 (${\varepsilon}_r$)는 89~92, Q, f는 5855-6091 GHz, 그리고 공진 주파수의 온도계수 (${\tau}_f$)는 -7.7-7.5 ppm/$^{\circ}C$이었다.

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Na2Ti6O13를 도핑한 0.94BaTiO3-0.06(Bi0.5Na0.5)TiO3 세라믹스의 미세구조와 Positive Temperature Coefficient of Resistivity 특성 (Microstructure and Positive Temperature Coefficient of Resistivity Characteristics of Na2Ti6O13-Doped 0.94BaTiO33-0.06(Bi0.5Na0.5)TiO3 Ceramics)

  • 차유정;정영훈;이영진;백종후;이우영;김대준
    • 한국재료학회지
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    • 제20권11호
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    • pp.575-580
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    • 2010
  • The microstructure and positive temperature coefficient of resistivity (PTCR) characteristics of 0.1 mol%$Na_2Ti_6O_{13}$ doped $0.94BaTiO_3-0.06(Bi_{0.5}Na_{0.5})TiO_3$ (BBNT-NT001) ceramics sintered at various temperatures from $1200^{\circ}C$ to $1350^{\circ}C$ were investigated in order to develop eco-friendly PTCR thermistors with a high Curie temperature ($T_C$). Resulting thermistors showed a perovskite structure with a tetragonal symmetry. When sintered at $1200^{\circ}C$, the specimen had a uniform microstructure with small grains. However, abnormally grown grains started to appear at $1250^{\circ}C$ and a homogeneous microstructure with large grains was exhibited when the sintering temperature reached $1325^{\circ}C$. When the temperature exceeded $1325^{\circ}C$, the grain growth was inhibited due to the numerous nucleation sites generated at the extremely high temperature. It is considered that $Na_2Ti_6O_{13}$ is responsible for the grain growth of the $0.94BaTiO_3-0.06(Bi_{0.5}Na_{0.5})TiO_3$) ceramics by forming a liquid phase during the sintering at around $1300^{\circ}C$. The grain growth of the BBNT-NT001 ceramics was significantly correlated with a decrease of resistivity. All the specimens were observed to have PTCR characteristics except for the sample sintered at $1200^{\circ}C$. The BBNT-NT001 ceramics had significantly decreased $\tilde{n}_{rt}$ and increased resistivity jump with increasing sintering temperature at from $1200^{\circ}C$ to $1325^{\circ}C$. Especially, the BBNT-NT001 ceramics sintered at $1325^{\circ}C$ exhibited superior PTCR characteristics of low resistivity at room temperature ($122\;{\Omega}{\cdot}cm$), high resistivity jump ($1.28{\times}10^4$), high resistivity temperature factor (20.4%/$^{\circ}C$), and a high Tc of $157.9^{\circ}C$.

Tunable 소자 응용을 위한 Sol-gel 법으로 제작된 BST 박막의 Bi 첨가에 따른 구조적, 유전적 특성 (Structure and Dielectric properties of BST Thin Films prepared by Sol-gel method for Tunable element application)

  • 김태형;김경태;김창일
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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    • pp.565-568
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    • 2004
  • An alkoxide-based sol-gel method was used to fabricate $Ba_{0.6}Sr_{0.4}TiO_3$ thin films doped by Bi from 5 to 20 mol% on a Pt/Ti/SiO2/Si substrate. The structural and dielectric properties of BST thin films were investigated as a function of Bi dopant concentration. The dielectric properties of the Bi doped BST films were strongly dependent on the Bi contents. The dielectric constant and dielectric loss of the films decreased with increasing Bi content. However, the leakage current density of the 10 mol% Bi doped $Ba_{0.6}Sr_{0.4}TiO_3$ thin film showed the lowest value of 5.13 10-7 at 5 V. The figure of merit (FOM) reached a maximum value of 32.42 at a 10 mol% Bi doped $Ba_{0.6}Sr_{0.4}TiO_3$ thin films. The dielectric constant, loss factor, and tunability of the 10 mol% Bi doped $BBa_{0.6}Sr_{0.4}TiO_3$ thin films were 333,0.0095, and 31.1%, respectively.

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Sol-gel 법으로 제작된 BST 박막의 Bi 첨가에 따른 구조적, 유전적 특성 (Fabrication of BST thin films with Bi addition by Sol-gel method and their Structure and Dielectric properties)

  • 김경태;김창일
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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    • pp.18-21
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    • 2004
  • An alkoxide-based sol-gel method was used to fabricate $Ba_{0.6}Sr_{0.4}TiO_3$ thin films doped by Bi from 5 to 20 mol% on a $Pt/Ti/SiO_2/Si$ substrate. The structural and dielectric properties of BST thin films were investigated as a function of Bi dopant concentration. The dielectric properties of the Bi doped BST films were strongly dependent on the Bi contents. The dielectric constant and dielectric loss of the films decreased with increasing Bi content. However, the leakage current density of the 10 mol% Bi doped $Ba_{0.6}Sr_{0.4}TiO_3$ thin film showed the lowest value of $5.13{\times}10^{-7}\;A/cm^2$ at 5 V. The figure of merit (FOM) reached a maximum value of 32.42 at a 10 mol% Bi doped $Ba_{0.6}Sr_{0.4}TiO_3$ thin films. The dielectric constant, loss factor, and tunability of the 10 mol% Bi doped $Ba_{0.6}Sr_{0.4}TiO_3$ thin films were 333, 0.0095, and 31.1%, respectively.

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