• Title/Summary/Keyword: Relaxor

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Ferroelectric to Relaxor Transition Behavior in Lead-Free Ternary (Bi0.5Na0.5)TiO3-BiFeO3-SrTiO3 Piezoceramics (Bi0.5Na0.5TiO3-BiFeO3-SrTiO3 삼성분계 무연 압전 세라믹스의 강유전체-완화형 강유전체 상전이 거동)

  • Lee, Sang Sub;Lee, Chang-Heon;Duong, Trang An;Nguyen, Hoang Thien Khoi;Han, Hyoung-Su;Lee, Jae-Shin
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.34 no.1
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    • pp.1-7
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    • 2021
  • This study investigated the structural, dielectric, ferroelectric, and strain properties of (0.98-x)Bi1/2Na1/2TiO3-0.02BiFeO3-xSrTiO3 (BNT-BF-100xST, x=0.20, 0.22, 0.24, 0.26, and 0.28). All samples were successfully synthesized using the conventional solid-state reaction method and sintered at 1,175℃ for 2 h. The average grain size of the BNT-BF-100x ceramics decreased with increasing ST content. Furthermore, we observed that the ferroelectric- relaxor transition temperature (TF-R) decreased with increasing ST content, which eventually vanished in the BNT-BF-24ST ceramics. The results indicated that a ferroelectric to relaxor phase transition could be induced by ST modification. Consequently, a large electromechanical strain of 633 pm/V at 4 kV/mm was observed for the BNT-BF-26ST ceramics. These results imply that our materials have the competitive advantage of larger strain under lower operating field conditions compared with other BNT-based lead-free piezoelectric ceramics. We expect that BNT-BF-ST lead-free piezoelectric ceramics are promising candidates as a novel ternary BNT-based system and can find potential applications in actuators.

Electrocaloric Effect in Pb0.865La0.09(Zr0.65Ti0.35)O3 Thin Film

  • Roh, Im-Jun;Kwon, Beomjin;Moon, Hi Gyu;Kim, Jin-Sang;Kang, Chong-Yun
    • Journal of Sensor Science and Technology
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    • v.23 no.4
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    • pp.224-228
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    • 2014
  • The electrocaloric effect of 9/65/35 PLZT thin film fabricated by the sol-gel method, which has not been studied yet, was investigated for its structural, electrical properties as well as temperature change property. The relaxor ferroelectric property of 9/65/35 PLZT thin film was confirmed by examining its dielectric and electrical properties. The relaxor property can cause a more pronounced electrocaloric effect (ECE) in a wider temperature range than normal ferroelectric film. To avoid errors caused by using an indirect measurement method, the leakage current generated by increasing temperatures was minimized by using the optimal maximum electric field ($350kVcm^{-1}$) in the thin film. The largest temperature change ${\delta}T$ (0.23 K) and the electrocaloric strength ${\xi}$ (0.68 mkcm/kV), calculated by equations were obtained. The maximum field change ${\delta}E$ ($191kVcm^{-1}$) was in the vicinity of the curie temperature ($200^{\circ}C$).

Correlations between the Polarization and Strain Induced by Electric field in $\textrm{0.9Pb}\textrm({Mg}_{1/3}\textrm{Nb}_{2/3})\textrm{O}_3$-$\textrm{0.1PbTiO}_3$ Relaxor Ferroelectrics ($\textrm{0.9Pb}\textrm({Mg}_{1/3}\textrm{Nb}_{2/3})\textrm{O}_3$-$\textrm{0.1PbTiO}_3$계 강유전체에서 전계인가에 따른 분극 및 변위의 상관관계)

  • Park, Jae-Hwan;Park, Jae-Gwan;Park, Sun-Ja
    • Korean Journal of Materials Research
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    • v.9 no.1
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    • pp.81-85
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    • 1999
  • Polarization and strain induced by unipolar electric field (P\ulcorner, S\ulcorner), those induced by bipolar electric field (P, S) and remanent polarization (P\ulcorner) were investigated in 0.9Pb(Mg\ulcornerNb\ulcorner)O$_3$-$0.1PbTiO_3$relaxor ferroelectric ceramics in the temperature range of $-50^{\circ}C$~$90^{\circ}C$. From the temperature dependence of polarization and strain, the transition from predominantly paraelectric (electrostrictive) to partially ferroelectric (piezoelectric) is visualized. Under the given temperature, the P\ulcorner/P\ulcorner is always larger than the S\ulcorner/S\ulcorner and the difference between them becomes larger ass the temperature decrease. The S\ulcorner/P\ulcorner increases as the temperature decreased below phase transition temperature. It was suggested that these experimental results might be explained with a simple rigid ion model concentrating on BO\ulcorner octahedron.

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Effect of $MnO_2$ Addition on the Electric Properties in Pb($Mg_{1/3}Nb_{2/3}$)$O_3$ Relaxor Ferroelectrics ($MnO_2$ 첨가에 따른 Pb($Mg_{1/3}Nb_{2/3}$)$O_3$계 완화형 강유전체에서의 전기적 물성변화)

  • 박재환
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.7
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    • pp.562-566
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    • 2001
  • The effects of MnO$_2$ addition on the properties in Pb(Mg$_{1}$3/Nb$_{2}$3/)O$_3$ relaxor ferroelectrics were studied in the phase transition temperature range from -4$0^{\circ}C$ to 11$0^{\circ}C$. Specimens were made via solid state processing method. Dielectric properties, piezoelctric properties, electric-field-induced strain were examined to clarify the effect of MnO$_2$ addition in 0.9MN-0.1PT. As the amount of MnO$_2$ increases, the maximum dielectric constant and the dielectric loss decreases. Q$_{m}$ increased by increasing the doping contents of Mn. When 0.5wt% MnO$_2$ was doped, Q$_{m}$ increased from 95 to 480. The electric-filed-induced strain and polarization decreases as the amount of MnO$_2$ increases. From the experimental results, it was suggested that Mn behaves as an ferroelectric domain pinning element.ent.

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Effect of PbTiO3 Concentration on the Properties of $Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3$ Relaxor Ferroelectrics -II. Phase Transition and Electric-field-induced Strains- ($Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3$계 완화형 강유전체의 특성에 미치는 PbTiO3 첨가량의 영향 -II. 상전이 및 전계인가 변위특성-)

  • 박재환;김인태;김동영;조서용;흥국선;박순자
    • Journal of the Korean Ceramic Society
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    • v.33 no.5
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    • pp.556-562
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    • 1996
  • In order to understand the electrostrictive behavior of Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) solid solutions the dielectric constants the electric-field-induced strains and the pyroelectric coefficients of (1-x)PMN-xPT (x=0.1-0.4) were investigated in the temperature range -50~20$0^{\circ}C$. For x=0.1~0.35 where the phase transi-tion is diffusive the strain has a maxima at the temperature of maximum pyroelectric coefficient (depolrizing temperature) rather than the temperature of maximum dielectric constant. For x=0.4 where the phase transition is relatively sharp the strain decreases monotonically as the temperature increases. Relationships among the above experimental results are discussed.

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