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    Electrical properties of bismuth potassium titanate-strontium titanate ferroelectric ceramics
    (2010-07-30)
    Phetnoi, Prapapim
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    Niemcharoen, Surasak
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    Sutapun, Manoon
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    In this paper, lead-free (Bi<inf>0.5</inf>K<inf>0.5</inf>)TiO<inf>3</inf> ceramics doped with SrTiO<inf>3</inf> was prepared by the conventional solid state reaction method with sintering temperature at 1040°C. The samples were characterized by X-ray diffraction analysis and Scanning Electron Microscopy. The dielectric, ferroelectric properties were also investigated. The results of X-ray diffraction reveal that SrTiO<inf>3</inf> diffuse into the Bi <inf>0.5</inf>K<inf>0.5</inf>TiO<inf>3</inf> lattices to form a solid solution with a pure perovskite structure. After the introduction of SrTiO<inf>3</inf> into Bi<inf>0.5</inf>K<inf>0.5</inf>TiO<inf>3</inf>, the dielectric constant at room temperature (ε<inf>r</inf>) was found to decrease with increasing SrTiO<inf>3</inf>. The broadness of the dielectric constant peak was observed with increasing SrTiO<inf>3</inf> content, especially that of the 0.94Bi <inf>0.5</inf>K<inf>0.5</inf>TiO<inf>3</inf> - 0.06 SrTiO<inf>3</inf> ceramic which exhibited a very broad curve over a wide temperature range. The Bi <inf>0.5</inf>K<inf>0.5</inf>TiO<inf>3</inf> - SrTiO<inf>3</inf> system was expected to be a new and promising candidate for lead-free capacitors.
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    Item type:Publication,
    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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    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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    High piezoelectric response in the new coexistent phase boundary of 0.87BaTiO3-(0.13-x)BaZrO3-xCaTiO3
    (2015-12-05)
    Sutapun, Manoon
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    ; ;
    An investigation of the coexistent ferroelectric phase was carried out on the ternary system of 0.87BaTiO<inf>3</inf>-(0.13-x)BaZrO<inf>3</inf>-xCaTiO<inf>3</inf> [abbreviated as BT-BZ-xCT (where 0.00≤x≤0.13)]. Temperature-, frequency-dependent dielectric data, electric field-dependent strain and polarization as a function of composition are presented in order to understand the relationships of structure-properties and find the high piezoelectric response in this system. Results showed that ceramics in the composition range of 0.00≤x<0.04 were of a rhombohedral structure and transformed into a tetragonal structure at x>0.06. The multiphase coexistence of the rhombohedral and tetragonal phase in this system was identified at x=0.06. A large, virtually hysteresis-free electric field induced strain of 0.23% was achieved with the composition, x=0.06, at 40kV/cm on the boundary between rhombohedral and tetragonal phase. This relates to an extraordinarily high and normalized piezoelectric coefficient (S<inf>max</inf>/E<inf>max</inf>) of 1280pm/V, which was reached at a low electric field applied at 10kV/mm. These results indicated that a high piezoelectric response may stem primarily from the rhombohedral-tetragonal phase boundary, due to greater lattice softening and reduced energy barriers for polarized rotation.
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    Phase transition, dielectric and piezoelectric properties of lead-free piezoelectric (K1/2Na1/2)NbO3 - Bi(Zn2/3Nb1/3)O3 ceramics
    (2016-01-02)
    Sutapun, Manoon
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    The lead-free piezoelectric ceramics on the binary system of (1-x)(K<inf>1/2</inf>Na<inf>1/2</inf>)NbO<inf>3</inf>-xBi(Zn<inf>2/3</inf>Nb<inf>1/3</inf>)O<inf>3</inf> [(1-x)KNN-xBZnN]; x = 0.01-0.10 were fabricated by the solid state reaction method. The structure and phase transition were determined by X-ray diffraction.The results of XRD patterns suggested that Bi(Zn<inf>2/3</inf>Nb<inf>1/3</inf>)O<inf>3</inf> completely diffuse into the (K<inf>1/2</inf>Na<inf>1/2</inf>)NbO<inf>3</inf> lattices to form a solid solution. The crystal structure was in an orthorhombic phase for x ≤ 0.01. When reaching 0.01 < x ≤ 0.07, crystal structure became a rhombohedral phase and transformed to a pseudo-cubic structure for x > 0.07. The dielectric data shows that the amount of Bi(Zn<inf>2/3</inf>Nb<inf>1/3</inf>)O<inf>3</inf> added in the (K<inf>1/2</inf>Na<inf>1/2</inf>)NbO<inf>3</inf> decreases the ferroelectric - paraelectric transition temperature progressively. Furthermore, optimum piezoelectric and ferroelectric properties were observed at the composition, x = 0.01: effective piezoelectric coefficients (d<inf>33</inf>) = 498 pm/V, remanent polarization (P<inf>r</inf>) = 23.3 μC/cm<sup>2</sup>, coercive field (E<inf>c</inf>) = 14 kV/cm, maximum strain (Sma<inf>x</inf>) = 0.3% and Curie temperature (T<inf>C</inf>) = 380°C. The results of this study show that KNN with a small amount of Bi(Zn<inf>2/3</inf>Nb<inf>1/3</inf>)O<inf>3</inf> (x = 0.01) can be one of lead-free piezoelectric ceramic candidate.