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    Electrical and dielectric properties of barium titanate–polydimethylsiloxane nanocomposite with 0-3 connectivity modified with carbon nanotube (CNT)
    (2019-01-02)
    Nawanil, Chanisa
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    Makcharoen, Worawut
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    Khaosa-Ard, Krittanat
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    ;
    This study explored the preparation and electrical properties of 0–3 barium titanate/polydimethylsiloxane nanocomposites by dispersing barium titanate nanoparticles (BaTiO<inf>3</inf>; BT) into the polydimethylsiloxane (PDMS) matrix phase. The effect of barium titanate nanoparticles on electrical properties has been investigated systematically, and the relative permittivity of nanocomposites was found to increase significantly with increasing barium titanate content. Different theoretical models were used to predict the dielectric constant of these composites and compare their experimental value with the theoretical value in order to find an appropriate equation. The result indicated that the dielectric properties of composites are influenced not only by relative permittivity of the components but also dependence on interactions between ceramics and polymers. Furthermore, the preparation and dielectric properties of BT/PDMS nanocomposites modified with carbon nanotube (CNT) were also studied. The dielectric results demonstrate that adding CNT can enhance the relative permittivity of the BT/PDMS composite via improvement of dispersion and distribution of the BT nanoparticles in the PDMS matrix phase. Moreover, the electrical outputs from the BT/PDMS/CNT nanocomposites generator were measured under periodic knocking. The nanocomposites innovatively expand the feasibility of self-powered energy systems for smart sensor and energy harvesting applications.
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    Phase transition and dielectric properties of lead free (K 0.5Na0.5)NbO3- Bi(Zn0.5Ti 0.5)O3 piezoelectric ceramics
    (2009-12-01)
    Sutapun, Manoon
    ;
    Lead-free piezoelectric ceramics of (1-x)(K0.5Na0.5) NbO3 - x(Bi(Zn0.5Ti0.5)O3; x = 0.00-0.30 were prepared via the two-stage mixed oxide fabrication technique. The crystal structure and ferroelectric phase transitions were studied by means of x-ray diffraction and thermal measurements. XRD results showed that a single-phase perovskite structurewas formed in the ceramics with x ≤ 0.25. For the ceramics with x = 0.30, a small amount of secondary phase Bi2Ti2O7 with a cubic structure was formed. The ceramics with a perovskite structure showed an orthorhombic phase at 0.00 ≤ x ≤ 0.010 and became rhombohedral at 0.010 < x ≤ 0.015 before transforming to a cubic phase at 0.015 < x ≤ 0.25. In addition, DSC results showed that the phase transition temperature of orthorhombic-tetragonal (TO-T) and tetragonal-cubic (TC) decreased when a small amount of BZT was added. The trend of enthalpy for orthorhombic → tetragonal phase transition and tetragonal → cubic phase were found to reduce with progressive increases in small amounts of BZT content. This behavior could originate from the more complex occupation of the A and B sites in an ABO3 perovskite structure. Copyright © Taylor & Francis Group, LLC.
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    Phase transition behaviour and electrical properties of lead-free (K 0.5Na0.5)NbO3-LiNbO3-LiSbO 3 piezoelectric ceramics
    (2011-05-01) ;
    Niemcharoen, Surasak
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    Sutapun, Manoon
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    ;
    The ternary system of 0.945(K<inf>0.5</inf>Na<inf>0.5</inf>NbO <inf>3</inf>)-(0.055 - x)LiNbO<inf>3</inf>-xLiSbO<inf>3</inf> [0.945KNN-(0.055 - x)LN-xLS]; x = 0.0-0.055 lead-free piezoelectric ceramics was fabricated by the conventional mixed oxide method with normal sintering. The crystal structure was studied by means of X-ray diffraction (XRD). The results of XRD patterns show that complete solid solutions of the mixed phase between the orthorhombic and tetragonal perovskite phase were observed. The DSC and dielectric data show that the amount of LiSbO<inf>3</inf> in K<inf>0.5</inf>Na<inf>0.5</inf>NbO <inf>3</inf>-LiNbO<inf>3</inf> solid solution slightly decreases the paraelectric cubic-ferroelectric tetragonal phase transition (T<inf>C</inf>) to a low temperature. Furthermore, good dielectric and piezoelectric properties were observed at composition, x = 0.03. The polymorphic phase transition between the orthorhombic and tetragonal phases plays a very important role in enhancement of the piezoelectric properties of KNN-LN-LS ceramics. © 2010 Elsevier B.V. All rights reserved.
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    Phase transition, mechanical, dielectric and piezoelectric properties of perovskite (Pb1-xBax)ZrO3 ceramics
    (2007-01-01) ;
    Bongkarn, Theerachai
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    Rujijanagul, Gobwute
    (Pb<inf>1-x</inf>Ba<inf>x</inf>)ZrO<inf>3</inf> ceramics were prepared in the composition range 0.00≤x≤0.30 by the mixed oxide solid-state reaction method. The samples were kept at the calcination temperature 1000 °C for 1 h and at the sintering temperature 1300 °C for 3 h. The structural phase transitions and the dielectric properties were studied. It was found that the density of the ceramics decreases with increasing amount of Ba<sup>2+</sup>, whilst the average grain size is in the range 1-2.3 μm. The structure of as-calcined powder reveals that the fraction of the orthorhombic phase is decreasing with increasing Ba<sup>2+</sup> content. The values of Vickers and Knoop hardness are in the range of 4.10-6.48 and 4.15-5.67 GPa, respectively. Dielectric measurements show that the antiferroelectric phase (AFE)-ferroelectric phase (FE) and the FE to paraelectric phase (PE) phase transformation temperatures decrease with increasing Ba<sup>2+</sup> concentration. The AFE-FE phase transformation is detected for compositions 0.00≤x≤0.075. The maximum dielectric constant gradually increases with increasing composition up to x=0.20. For higher Ba<sup>2+</sup> concentrations, the lowering of the maximum dielectric value is accompanied by a progressive broadening of the permittivity peak. The d<inf>33</inf> values of the samples increase from ∼0 to 87 pC/N with increasing Ba<sup>2+</sup> concentration from x=0.00 to 0.30. © 2006 Elsevier B.V. All rights reserved.
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    Synthesis and properties of Pb(Co1/3Nb2/3)O3 ceramics
    (2008-10-20)
    Unruan, Muangjai
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    Wongmaneeruang, Rewadee
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    Prasatkhetragarn, Anurak
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    Ananta, Supon
    In this study, Pb(Co<inf>1/3</inf>Nb<inf>2/3</inf>)O<inf>3</inf> or PCN ceramics have been produced by sintering PCN powders synthesized from lead oxide (PbO) and cobalt niobate (CoNb<inf>2</inf>O<inf>6</inf>) with an effective method developed for minimizing the level of PbO loss during sintering. Attention has been focused on relationships between sintering conditions, phase formation, density, microstructural development, dielectric and ferroelectric properties of the sintered ceramics. The densities of sintered PCN ceramics increased with increasing sintering temperature. However, it was observed that at too high temperature the density began to decrease. Change of dielectric properties with sintering temperature also followed the same trend as the density. Based on X-ray diffraction analysis, density data, SEM micrograph, and dielectric properties, the optimum sintering temperature for a high purity PCN ceramic was found to be about 1100 and 1150 °C. A strongly diffused dielectric peak also showed a typical characteristic of ferroelectric relaxors. The P-E hysteresis loops observed at -70 °C were of slim-loop type with small remnant polarization values, which confirmed relaxor ferroelectric behavior of PCN ceramics. © 2007 Elsevier B.V. All rights reserved.
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    Phase transitional behavior and dielectric properties of lead free (1-x)(K0.5Na0.5)NbO3-xBi (Zn0.5Ti0.5)O3 ceramics
    (2009-06-24)
    Sutapun, Manoon
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    Huang, Chien Chih
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    Cann, David P.
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    Lead-free ceramics based on potassium sodium niobate [(K<inf>0.5</inf>Na<inf>0.5</inf>)NbO<inf>3</inf>; KNN]-bismuth zinc titanate [Bi(Zn<inf>0.5</inf>Ti<inf>0.5</inf>)O<inf>3</inf>; BZT] were prepared by the modified-conventional mixed oxide route with normal sintering. The crystal structure and ferroelectric phase transitions were studied by means of X-ray diffraction, thermal and dielectric measurements. The ceramics with perovskite structure were in orthorhombic phase at x ≤ 0.010. When reaching 0.01 < x ≤ 0.03, they became a rhombohedral perovskite structure; and with increasing BZT content, cubic within the studied composition range. The phase Bi<inf>2</inf>Ti<inf>2</inf>O<inf>7</inf> with cubic structure began to appear at x > 0.25 and became dominant while increasing the content of BZT. Furthermore, the phase transition temperature of orthorhombic-tetragonal (T<inf>O-T</inf>) and tetragonal-cubic (T<inf>C</inf>) decreased when a small amount of BZT was added. As the amount of BZT concentration increased, the structure became denser, and well developed grain morphology with almost no porosity was finally obtained. © 2008 Elsevier B.V. All rights reserved.
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    The improvement in dielectric and ferroelectric performance of PZT-PZN ceramics by thermal treatment
    (2007-07-01) ;
    Rujijanagul, Gobwute
    ;
    Cann, David P.
    Pyrochlore-free lead zirconate titanate - lead zinc niobate ceramics have been systematically investigated in the as-sintered condition as well as after annealing. The ceramics were characterized by dielectric spectroscopy and Sawyer-Tower polarization (P-E) measurements. The powders of Pb[(Zr<inf>1/2</inf>Ti<inf>1/2</inf>)<inf>(1-x)</inf>-(Zn<inf>1/3</inf>Nb<inf>2/3</inf>)<inf>x</inf>]O<inf>3</inf>, where x = 0.1, 0.3 and 0.5 were prepared using the columbite-(wolframite) precursor method. The general trend seems to indicate that the annealed samples become more normal-ferroelectric-like behavior as opposed to the relaxor-ferroelectric-like behavior observed in the as-sintered state. The as-sintered 0.9PZT-0.1PZN ceramic exhibited weak relaxor-ferroelectric behavior, with a relatively low dielectric constant maximum of 14,000 measured at 1 kHz. Annealing resulted in a transition to normal-ferroelectric-like behavior, a shift in the dielectric maximum temperature from 360 °C to 350 °C, and a dramatic increase in the dielectric constant at 1 kHz to a maximum value of 35,000 for the longer anneal. After thermal annealing at 900 °C for one week a strong enhancement of remanent polarization (P<inf>r</inf>) was observed. © 2007 Elsevier B.V. All rights reserved.
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    Influence of fabrication processing on perovskite phase formation of KNN-BZT
    (2008-01-01)
    Sutapun, M.
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    Huang, C. C.
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    Cann, D. P.
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    Vittayakorn, W. C.
    The binary system of (1-x)(K<inf>1/2</inf>Na<inf>1/2</inf>)NbO <inf>3</inf>-xBi(Zni/2Ti<inf>1/2</inf>)O<inf>3</inf>; x = 0.0-0.30 ceramics was fabricated by conventionally mixed oxide and two-stage mixed oxide methods. Phase development of calcined powders and the crystal structure of sintered ceramics were analyzed by X-ray diffraction (XRD). The microstructure analyses were undertaken by scanning electron microscopy (SEM). In the conventional method, the perovskite phases were obtained for compositions containing only 10 mol % KNN. For compositions above this amount, a complex mixture of phases was observed. However, the complete solid solution of perovskite phase, prepared by two-stage mixed oxide, was retained up to 20 mole % BZT content. The experiments in this study suggest that the two-stage mixed oxide method helps to stabilize the perovskite phase better, when compared with the conventional method. © 2008 Trans Tech Publications, Switzerland.
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    Synthesis, characterization and dielectric properties of Mn(2-x)znxP2O7 ceramics
    (2013-10-29)
    Sutapun, Manoon
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    ;
    Niemcharoen, Surasak
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    ;
    Manganese zinc pyrophosphate (Mn<inf>(2-x)</inf>Zn<inf>x</inf>P<inf>2</inf>O<inf>7</inf> when x = 0.0, 0.5, 1.0, 1.5 and 2.0) ceramics were fabricated by conventionally mixing oxide using the normal sintering method. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Raman spectroscopy and scanning electron microscopy (SEM). The XRD results indicated that synthesized Mn<inf>(2-x)</inf>Zn<inf>x</inf>P<inf>2</inf>O<inf>7</inf> systems have a pure monoclinic phase without the presence of phase impurities. The lattice parameters and crystalline sizes analyzed from XRD data were changed depending on the amount of added Zn<sup>2+</sup> ion concentration in the Mn<inf>2</inf>P<inf>2</inf>O<inf>7</inf> structure. The FT-IR and Raman results showed the fundamental vibrations of P<inf>2</inf>O<inf>7</inf> <sup>4-</sup> ion and Mn-O or Zn-O, which confirmed the Mn<inf>(2-x)</inf>Zn<inf>x</inf>P<inf>2</inf>O<inf>7</inf> formation. In addition, dielectric stability of temperature and frequency was observed in the composition, x = 1.0, with a dielectric constant value of 11.5 at 1 MHz. © (2013) Trans Tech Publications, Switzerland.
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    Preparation and properties of lead free bismuth sodium titanate-bismuth zinc titanate ceramics
    (2009-12-01) ;
    Niemcharoen, Surasak
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    Tungsitvisetkul, Nattapong
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    Chinwaro, Pimjan
    Lead-free piezoelectric ceramics based on (1-x)Bi1/2Na1/2TiO3 - x Bi(Zn1/2 Ti1/2)O3 (x = 0.0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, 0.30, 0.40, and 0.5) were obtained via solid-state processing techniques. The influence of BZT addition on BNT characteristics, sintering, microstructure and properties was investigated. A single perovskite phase with rhombohedral symmetry was obtained for Bi(Zn1/2Ti1/2)O3 substitutions of up to 10 mole%. A small amount of BZT was effective for improving both sintering behavior and dielectric properties of BNT ceramics. Optimized dielectric properties were obtained for samples with a maximum density of ρ = 98.3% for the composition, x = 0.1. Copyright © Taylor & Francis Group, LLC.