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- 주제어 : Ferroelectric properties (검색결과 160 건)
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Sukum Eitssayeam,Uraiwan Intatha,Kamonpan Pengpat,Gobwute Rujijanagul,Kenneth J.D. MacKenzie,Tawee Tunkasiri 한국물리학회 2008 Current Applied Physics Vol.8 No.3,4
Relaxor ferroelectrics with A'A"(B'B")O₃- type perovskite structures have attracted much attention because of their excellent dielec-tric and electromechanical properties. The physical properties or device parameters of PZT can be tailored by improved synthesis andprocessing techniques and by making suitable substitutions into the A and/or B sites. In this study, Pb0.84Ba0.16(Zr0.44Ti0.40-Fe0.08Nb 0.08)O₃ ceramics were prepared by solid state reaction and the eect of the processing parameters on the ferroelectric, dielectricand pyroelectric properties was determined. Optimal dielectric properties were achieved in Pb0.84Ba0.16(Zr0.44Ti0.40Fe0.08Nb 0.08)O₃ ceramics by calcination at 1100.C and sintering at 1250℃. Hysteresis loop measurements of these materials indicated a remanent polarization(Pr) and spontaneous polarization (Ps) of 15.88 μC/cm² and 26.29 μC/cm², respectively. TEM micrographs showed nano-domains in thecalcined powder conrming their ferroelectric properties. The dielectric properties also show ferroelectric behavior, with a Curie temper-ature of approximately 220℃. The values ofpi show a continuous increase with increasing temperature up to a maximum value. 800 nC/cm² K at~120℃.
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김진수,Saes Byul Kim,최병춘,정중현,Young Woo No,Su Tae Chung,Se Mo Son 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.2
To investigate the effect of La-ion doping, we prepared pure Na1/2Bi1/2TiO3 (NBT) and La-doped Na1/2Bi1/2-xLaxTiO3 (NBLT) ceramics by using a solid-state reaction method. Crystallized NBT and NBLT single-phases were confirmed by using X-ray diffraction. The La doping influenced the dielectric behavior and the ferroelectric properties. With increasing La doping, the dielectric peak broadened. The ferroelectric P-E hysteresis loop changed from a leaky shape to a slim shape. The remanent polarization slightly decreased; however, the coercive electric field decreased remarkably. In this work, the La-doping effects on the dielectric and the ferroelectric properties of lead-free NBT ferroelectric ceramics were investigated by using X-ray diffraction, dielectric constant and ferroelectric P-E hysteresis loop measurements.
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Xu-mei Zhao,Xiao-Ming Chen,Jian Wang,Xiao-xia Liang,Jian-Ping Zhou,Peng Liu 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.1
The lead-free ceramics (Na0.54Bi0.5)0.94Ba0.06Ti1+xO3 with x = −0.02, 0, 0.02, and 0.04 were prepared by a solid-state reaction method. Effects of Ti4+ nonstoichiometry on crystallite structure, microstructure, dielectric, ferroelectric and piezoelectric properties were studied. The ceramics with x = −0.02 and 0 exhibit typical diffraction peaks of perovskite structure. A secondary phase appears in the ceramics with x = 0.02 and 0.04. The rhombohedral-tetragonal morphotropic phase boundary exists in all samples, and the relative amount of the tetragonal phase changes with the increase in the Ti4+ amount from deficiency to excess. Grain sizes and shape of the ceramics are unaffected by changes in Ti4+ nonstoichiometry. But, dielectric, ferroelectric and piezoelectric properties of the ceramics are close related to the Ti4+ amounts. Compared with the ceramic with x = 0, the ceramics with the Ti4+ nonstoichiometry have higher depolarization temperature, lower maximum dielectric constant, decreased piezoelectric constant and ferroelectric properties.
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김진원,도달현,김상수,송태권,최병춘,김원정,김명호 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.31
We explore new systems of BiFeO3-Na0.5Bi4.5Ti4O15 (NaBFT) and BiFeO_3-M_(0.5)Bi_(4.5)Ti_4O_(15) (KBFT) solid solutions, where our interest is focused on ferroelectric properties. The NaBFT and the KBFT thin films were prepared by a chemical solution deposition method. The crystal structure and the surface morphology of the thin films were characterized by means of X-ray diffraction, Raman spectroscopy and scanning electron microscopy. The values of remnant polarization (2P_r) were 76.5 and 70.9 μC/cm^2 at an electric field of 663 kV/cm for the NaBFT and the KBFT thin films, respectively. The values of dielectric constant were 748 and 717 at a frequency of 1 kHz for the NaBFT and the KBFT thin films, respectively. The values of leakage current density of the KBFT and the NaBFT thin films were 6.9 × 10^(-7) and 5.9 × 10^(-6) A/cm^2 at an electric field of 100 kV/cm, respectively. Both thin films showed no polarization fatigue up to 1.4 × 10^(10) switching cycles. The good ferroelectric properties observed in the thin films may be related to the reduction of bismuth vacancies and oxygen vacancies.
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김진수,정창희,이호섭,정수태 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.58 No.31
To investigate the effect of LiNbO_3 doping on Bi_(0.5)Na_(0.5)TiO_3 (BNT), we prepared LiNbO_3 doped (1-x)Bi_(0.5)Na_(0.5)TiO_3: xLiNbO_3 (BNT:LN) ceramics by using a solid-state reaction method. Wellcrystallized lead-free BNT and BNT:LN ceramics formed a single phase with a perovskite structure. LiNbO_3 doping of Bi_(0.5)Na_(0.5)TiO_3 affected the dielectric behaviors and the ferroelectric properties. With increasing LiNbO_3 doping, the dielectric peak at the temperature of T_m = 340 ℃ broadened and shifted to low temperature. The ferroelectric polarization measurement indicated that a ferroelectric phase changed to a paraelectric phase, and the well saturated polarization-electric field (P-E) hysteresis loops exhibited at x = 0.03 ∼ 0.05. In this work, the effects of LiNbO_3 doping on the dielectric and the ferroelectric properties were investigated by using X-ray diffraction, scanning electron microscopy, grain morphology, dielectric constant, and P-E hysteresis loop measurements.
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Lee, Heejin,Joo, Ho-yong,Yoon, Chulmin,Lee, Joonbong,Lee, Hojin,Choi, Jinsik,Park, Baeho,Choi, Taekjib Elsevier 2017 Current Applied Physics Vol.17 No.5
<P>Ferroelectric based heterostructures have shown great promises in solar water splitting due to unique photoelectrochemical (PEC) properties including polarization-induced charge separation and tunable electrochemical surface reaction. A highly ordered ferroelectric BiFeO3/TiO2 nanotube (TNT) heterostructures were fabricated by anodic oxidation and pulsed laser deposition. The microscopic morphology, optical, and PEC properties of nanostructures were characterized. The BiFeO3/TNT photoelectrode is photoactive under visible light illumination, which exhibits higher photocurrent from greater water oxidation, compared with the pure TNT photoelectrode. The coating thickness of BiFeO3 strongly affected the photoelectrochemical properties. The enhanced PEC performance could be attributed to the effective charge separation and the favorable band bending for water oxidation, originating from ferroelectric polarization-related internal field. (C) 2017 Elsevier B.V. All rights reserved.</P>
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이완규,박병은,Kyoung Eun Park 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.3
Precursor films based on poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) and P(VDF-TrFE) blended with Pb(Zr,Ti)O3 were deposited on Si (100) substrates by spin-coating, and subsequently annealed at 443 K for 0.5 h. These films were then characterized using X-ray diffraction, atomic force microscopy and capacitance-voltage curves. Blending the precursor films of Pb(Zr,Ti)O3 with P(VDF-TrFE) led to the formation of an amorphous oxide whose concentration was proportional to the Pb(Zr,Ti)O3 content. This resulted in extension of the memory-window width with a large voltage difference ranging from 0.07 V to 4.5 V for metal-ferroelectric-silicon capacitors. Moreover, the formation of the amorphous oxide resulted in parallel shifts toward positive or negative voltages in the capacitance-voltage curves because of the fixed negative or positive charge of the oxide at the ferroelectric/Si-substrate interface. These tunable ferroelectric properties open up possibilities for diverse applications and are essential for functional devices, as well as for the commercialization of nonvolatile high-density FeRAM devices.
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Ferroelectric BiFeO3/TiO2 nanotube heterostructures for enhanced photoelectrochemical performance
이희진,주호용,윤철민,이준봉,이호진,최진식,박배호,최택집 한국물리학회 2017 Current Applied Physics Vol.17 No.5
Ferroelectric based heterostructures have shown great promises in solar water splitting due to unique photoelectrochemical (PEC) properties including polarization-induced charge separation and tunable electrochemical surface reaction. A highly ordered ferroelectric BiFeO3/TiO2 nanotube (TNT) heterostructures were fabricated by anodic oxidation and pulsed laser deposition. The microscopic morphology, optical, and PEC properties of nanostructures were characterized. The BiFeO3/TNT photoelectrode is photoactive under visible light illumination, which exhibits higher photocurrent from greater water oxidation, compared with the pure TNT photoelectrode. The coating thickness of BiFeO3 strongly affected the photoelectrochemical properties. The enhanced PEC performance could be attributed to the effective charge separation and the favorable band bending for water oxidation, originating from ferroelectric polarization-related internal field.
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Ali, Ahmed I.,Ahn, Chang Won,Kim, Yong Soo Elsevier 2013 Ceramics international Vol.39 No.6
<P><B>Abstract</B></P> <P>Ferroelectric and piezoelectric properties of BaTiO<SUB>3</SUB> and Al-doped BaTiO<SUB>3</SUB> ceramics were investigated. The ferroelectric study demonstrated that, by doping Al<SUP>3+</SUP> ions in the A-site of BaTiO<SUB>3</SUB>, the polarization–electric field loop exhibited enhanced remnant polarization (from 12 to 17.5 μC/cm<SUP>2</SUP>), saturation and switching. In addition, the piezoelectric constant (<I>d</I> <SUB>33</SUB>) increased with Al-doping for both static and dynamic strain values (from 75 to 135 and from 29.2 to 57.9pC/N, respectively, at a maximum applied electric field of 16kV/cm). Furthermore, the dielectric constant values increased and both the dielectric loss factor and leakage current decreased, even though the transition temperature shifted to lower temperature (from 121 to 113°C) for the Al-doped sample. Therefore, the Al-doped BaTiO<SUB>3</SUB> has adjustable piezoelectric and ferroelectric properties.</P>
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강우석,이건주,조욱 한국전기전자재료학회 2021 전기전자재료학회논문지 Vol.34 No.5
Theoretical background for the meaning of various piezoelectric properties can be easily found in a number of textbooks and academic papers. In contrast, how they are actually measured and characterized are rarely described, though this information would be the most important especially to the researchers who just started working on the field. It follows that this report was intended to provide a practical guidance for measuring basic but essential properties of ferroelectric-based piezoelectric materials. The discussion begins with how to measurement dielectric properties such as dielectric permittivity and loss (dissipation factor), followed by piezoelectric properties such as piezoelectric constants, electromechanical coupling factor, and quality factor as well as ferroelectric features, i.e., electric field dependent polarization hysteresis. Though our discussion here is limited to the techniques that are already well-standardized, it is expected to make a seed to be developed into more challenging and creative ones. 본 논문은 대학 연구실과 산업현장에서 강유전 압전 분야 연구를 갓 시작한 이들이 압전 소재의 특성에 대한 기초적, 이론적 개념에 대해서는 각종 교과서와 논문을 통해 쉽게 접할 수 있는 반면, 그 특성들이 실제로 어떻게측정되고 평가되는 지에 대한 정보를 얻기가 힘들다는 점에 착안하여 압전 분야 입문자가 관련 측정 기술을 보다 쉽게 이해하고 접근할 수 있도록 돕는 것을 목적으로 한다. 기초 유전 물성인 임피던스에 기반한 유전상수와유전손실 측정법을 시작으로 압전상수, 전기기계결합계수, 품질계수 및 측정 방법에 대해 논의하고, 강유전성을 대표하는 전계에 따른 분극 변화 측정법에 대해 기술하였다. 본 논문에서는 이미 표준화되어 있는 측정법들을소개하고 있지만, 이를 숙지하고 응용한다면 보다 도전적이고 창의적인 측정법을 도출할 수 있을 것으로 기대한다.
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