• Title/Summary/Keyword: $Bi_{0.5}K_{0.5}TiO_3$

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Investigation on PTCR Characteristics of (1-x)BaTiO3-x(Bi0.5Na0.5)TiO3 (0.01≤x≤0.10) Ceramics by Modified Synthesis Process (수정합성공정에 의한 무연 (1-x)BaTiO3-x(Bi0.5Na0.5)TiO3 (0.01≤x≤0.10) 세라믹의 PTCR 특성 연구)

  • Kim, Kyoung-Bum;Kim, Chang-Il;Jeong, Young-Hun;Lee, Young-Jin;Paik, Jong-Hoo;Lee, Woo-Young;Kim, Dae-Joon
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.12
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    • pp.929-935
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    • 2010
  • $(1-x)BaTiO_3-x(Bi_{0.5}Na_{0.5})TiO_3$ ($0.01{\leq}x{\leq}0.10$) ceramics were fabricated with muffled sintering by a modified synthesis process. Their positive temperature coefficient of resistivity (PTCR) characteristics were investigated systematically. All specimen showed a perovskite structure with a tetragonal symmetry. Both the lattice parameter of a and c axes were slightly decreased with increasing $(Bi_{0.5}Na_{0.5})TiO_3$ (BNT) content. Grain growth was achieved when the incorporated BNT was increased to 6 mol% and the inhibition of grain growth is considered to be due to the appearance of Ba vacancy ($V^{"}_{Ba}$) in the $(1-x)BaTiO_3-x(Bi_{0.5}Na_{0.5})TiO_3$ ($0.08{\leq}x$). With 4 mol% BNT addition, room temperature resistivity decreased to $48 \Omega{\cdot}cm$ and a resistivity jump ($\rho_{max}/\rho_{min}$) was as high as $1.1{\times}10^4$, respectively. Curie temperature was also increased to $171^{\circ}C$ with increasing BNT content.

비납계 $(1-x)(Bi_{0.5}K_{0.5})TiO_3-xBiFeO_3$ 세라믹의 유전 및 압전 특성

  • Kim, Jeong-Min;Seong, Yeon-Su;Song, Tae-Gwon;Kim, Myeong-Ho
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2009.05a
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    • pp.33.2-33.2
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    • 2009
  • Dielectric and piezoelectric properties of Lead-free $(1-x)(Bi_{0.5}K_{0.5})TiO_3-xBiFeO_3$ceramics prepared by a conventional solid state reaction method were investigated in the range of x = 0~10 mol%. Piezoelectric coefficient was increased from 31 pC/N at x = 0 mol% to 64 pC/N at x = 6 mol% then decreased with increasing x. Electromechanical coupling factor ($K_p$) was increased up to 0.18 at x = 10 mol%. On the other hand, mechanical quality factor ($Q_m$) was decreased. Grain size was not much changed with various x and a single perovskite with tetragonal symmetry was maintained at all compositions forming a solid solution between $(Bi_{0.5}K_{0.5})TiO_3$ and $BiFeO_3$. Depolarization temperature ($T_d$) was gradually decreased with increasing x from $302^{\circ}C$ at x = 0 to $245^{\circ}C$ at x = 10 mol%.

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Thermoelectric Properties of the n-type Bi2(Te0.9Se0.1)3 Processed by Hot Pressing with Dispersion of 0.5 vol% TiO2 Nanopowders (0.5 vol% TiO2 나노분말을 분산시킨 n형 Bi2(Te0.9Se0.1)3 가압소결체의 열전특성)

  • Park, D.H.;Oh, T.S.
    • Journal of the Microelectronics and Packaging Society
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    • v.20 no.1
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    • pp.15-19
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    • 2013
  • The n-type $Bi_2(Te_{0.9}Se_{0.1})_3$ powders, which were fabricated by melting/grinding method and dispersed with 0.5 vol% $TiO_2$ nanopowders, were hot-pressed in order to investigate the effects of $TiO_2$ dispersion on the thermoelectric properties of the hot-pressed $Bi_2(Te_{0.9}Se_{0.1})_3$. Excellent thermoelectric properties such as a maximum figure-of-merit of $2.93{\times}10^{-3}/K$ and a maximum dimensionless figure-of-merit of 1.02 were obtained for the hot-pressed $Bi_2(Te_{0.9}Se_{0.1})_3$. With dispersion of 0.5 vol% $TiO_2$ nanopowders, the maximum figure-of-merit and the maximum dimensionless figure-of-merit decreased to $2.09{\times}10^{-3}/K$ and 0.68, respectively.

Electrical Properties of (Bi,Y)4Ti3O12 Thin Films Grown by RF Sputtering Method

  • Nam, Sung-Pill;Lee, Sung-Gap;Bae, Seon-Gi;Lee, Young-Hie
    • Journal of Electrical Engineering and Technology
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    • v.2 no.1
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    • pp.98-101
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    • 2007
  • Yttrium(Y)-substituted bismuth titanate $(Bi_{4-x},Y_x)Ti_3O_{12}$ [x=0, 0.25, 0.5, 0.75, 1](BYT) thin films were deposited using an RF sputtering method on the $Pt/TiO_2/SiO_2/Si$ substrates. The structural properties and electrical properties of yttrium-substituted $(Bi_4-xYx)Ti_3O_{12}$ thin films were analyzed. The remanent polarization of $(Bi_4-xYx)Ti_3O_{12}$ films increased with increasing Y-content. The $(Bi_{3.25}Y_{0.75})Ti_3O_{12}$ films fabricated using a top Au electrode showed saturated polarization-electric field(P-E) switching curves with a remanent polarization(Pr) of $8{\mu}C/cm^2$ and coercive field (Ec) of 53 kV/cm at an applied voltage of 7 V. The $(Bi_{3.25}Y_{0.75})Ti_3O_{12}$ films exhibited fatigue-free behavior up to $4.5{\times}10^{11}$ read/write switching cycles at a frequency of 1MHz.

Dielectric and Piezoelectric Properties Of Lead-free (Bi0.5Na0.5)TiO3-BaTiO3 Ferroelectric Ceramics (비납계 (Bi0.5Na0.5)TiO3-BaTiO3 강유전 세라믹 재료의 유전 및 압전 특성)

  • Kuk Min-Ho;Kim Myong-Ho;Cho Jung-A;Sung Yeon-Soo;Song Tae Kwon;Bae Dong-Sik;Jeong Soon-Jong;Song Jae-Sung
    • Korean Journal of Materials Research
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    • v.15 no.11
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    • pp.683-689
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    • 2005
  • The structural, piezoelectric and ferroelectric properties of $(1-x)(Bi_{0.5}Na_{0.5})TiO_3$ x=0.00, 0.02, 0.04, 0.06, 0.08, and 0.10) ceramics were investigated. A gradual change in the crystal and microstructures with tile increase of $BaTiO_3$ (BT) concentration was observed. The $(Bi_{0.5}Na_{0.5})TiO_3$ (BNT) samples show unusual properties as ferroelectric relaxer materials. We observed a phase transition in BNT solid solutions with BT having normal ferroelectric phase transition. At room temperature, BNT presents a single phase without the morphotropic phase boundary (MPB). In the case of samples doped with $4\~8 mol\%$ BT, rhombohedral-tetragonal MPB was formed and the piezoelectric properties were improved.

A-site Non-stoichiometric Effects of Bi0.5(Na0.78K0.22)0.5TiO3 Ceramics on the Dielectric and Electrical Properties (Bi0.5(Na0.78K0.22)0.5TiO3 세라믹스의 A-site 비화학양론이 유전 및 전기적 특성에 미치는 영향)

  • Park, Jung Soo;Lee, Ku Tak;Yun, Ji Sun;Cho, Jeong Ho;Jeong, Young Hun;Paik, Jong Hoo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.27 no.12
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    • pp.803-808
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    • 2014
  • $Bi_{0.5+x}(Na_{0.78}K_{0.22})_{0.5-3x}TiO_3$ ceramics with an excess $Bi^{3+}$ and a deficiency of $Na^+$ and $K^+$ were synthesized by a conventional solid state reaction method. The structure and morphology of $Bi_{0.5+x}(Na_{0.78}K_{0.22})_{0.5-3x}TiO_3$ ceramics were characterized by X-ray diffraction and field emission scanning electron microscopy. The electric polarization and mechanical strain induced by external electric field, and the temperature dependence of dielectric constant were investigated. These results demonstrated that an ergodic relaxor phase can be induced by controls of the mole ratio of $Bi^{3+}$, $Na^+$ and $K^+$. A phase boundary between non-ergodic and ergodic relaxor phases can be observed at ambient temperature. The ergodic relaxor phase can be transferred to the ferroelectric phase by application of the electric field. The stability of the induced ferroelectric phases strongly depends on the mole ratio of $Bi^{3+}$, $Na^+$ and $K^+$. The maximum strain of 0.31% was observed in $Bi_{0.51}(Na_{0.78}K_{0.22})_{0.47}TiO_3$ ceramics sintered at $1,150^{\circ}C$ for 2 h.

Orientation of $(Na_{1/2}Bi_{1/2})TiO_3$ thin films deposited on $LaNiO_3$ electrodes by sol-gel methode (졸-겔법으로 $LaNiO_3$ 전극에 증착된 $(Na_{0.5}Bi_{0.5})TiO_3$ 박막의 배향성)

  • Park, Min-Seok;Yoo, Young-Bae;Moon, Byung-Kee;Son, Se-Mo;Chung, Su-Tae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07b
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    • pp.894-897
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    • 2004
  • Sodum bismuth titanate $(Na_{0.5}Bi_{0.5}TiO_3$ or NBT) thin films coated on the $LaNiO_3$ (LNO) electrode by sol-gel methode and rapid thermal annealing (RTA) technique. The NBT (NBT/LNO/Si) thin films examined by x-ray diffraction (XRD). The orientation of NBT was observed for films coated at $900^{\circ}C$, 5 min and $600^{\circ}C$, 60 min. Filed emission scanning electron microscopy (FE-SEM) showed uniform surface composed of grains. The grain size of NBT thin films increased with increasing annealing temperature.

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Frequency-temperature Characteristics of AT-cut Crystal Resonator Compensated by Bi0.5(Na0.84K0.16)0.5TiO3 Ceramics (Bi0.5(Na0.84K0.16)0.5TiO3 세라믹스로 보상된 AT-cut 수정 공진자의 주파수 온도특성)

  • Oh, Dong-On;Mun, Keyong-Hyeon;Yoo, Ju-Hyun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.7
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    • pp.610-614
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    • 2005
  • In this paper, simple AT-cut crystal resonator utilizing $Bi_{0.5}(Na_{0.84}K_{0.16})_{0.5}TiO_3$ relaxator ceramics as load capacitator were designed and their frequency-temperature characteristics were investigated. In order to modify temperature dependance of dielectric constant, $Bi_{0.5}(Na_{0.84}K_{0.16})_{0.5}TiO_3$ ceramics were manufactured with the variations in Sr substitution. At the composition with $6\;mol\%$ Sr substitution as load capacitator, frequency-temperature characteristics of AT-cut crystal resonators with the series load capacitance were similarly varied as those of cut orientation variation, and also compensated.

Effect of LaFeO3 Doping on the Ferroelectric and Piezoelectric Properties of Bi0.5(Na0.78K0.22)0.5TiO3 Lead-Free Piezoceramics (LaFeO3 함량에 따른 (1-x)Bi0.5(Na0.78K0.22)0.5TiO3-xLaFeO3의 강유전, 압전 특성)

  • Park, Chun-Kil;Lim, Ji-Ho;Park, Jung-Soo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.30 no.3
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    • pp.157-161
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    • 2017
  • $(1-x)Bi_{0.5}(Na_{0.78}K_{0.22})_{0.5}TiO_3-xLaFeO_3$ ceramics were fabricated using a solid state reaction method. The microstructural, ferroelectric and piezoelectric properties were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), and polarization hysteresis loops (P-E). XRD results indicated that BNKT ceramic crystal structure modified by $LaFeO_3$ was transformed from a ferroelectric tetragonal to a non-polar pesudo-cubic phase with increased $LaFeO_3$ content. The improved piezoelectric properties resulted from the addition of $LaFeO_3$ up to 3 mol%. The $LaFeO_3$ 3mol% sample showed markedly improved piezoelectric and strain behaviors in comparison with pure BNKT ceramic.

Low Temperature Sintering of BNKT Lead-Free Piezoelectric Ceramics Using CuO-Coated Na0.5Bi4.5Ti4O15 Templates (산화구리가 피복된 Na0.5Bi4.5Ti4O15 틀입자를 이용한 BNKT 무연 압전 세라믹스의 저온소성 연구)

  • Jeong, Gwang-Hwi;Lee, Sang-Seop;Ahn, Chang Won;Han, Hyoung Su;Lee, Jae-Shin
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.33 no.5
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    • pp.337-343
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    • 2020
  • This study investigated the low temperature sintering with various templates of Bi-based lead-free piezoelectric ceramics. The effects of using CuO-coated Na0.5Bi4.5Ti4O15 templates on the sintering behavior as well as the dielectric, ferroelectric, and piezoelectric properties of Bi1/2(Na0.78K0.22)1/2TiO3 (BNKT) ceramics have been examined. In comparison with the specimens sintered with the Na0.5Bi4.5Ti4O15 templates without CuO coating, those sintered with the CuO-coated Na0.5Bi4.5Ti4O15 templates showed larger template sizes as well as a larger electric field induced strain (Smax/Emax) of 422 pm/V after sintering at temperatures as low as 975℃. These results are promising for low-cost multilayer ceramic actuator applications.