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Synthesis, characterization and dielectric properties of Mn(2-x)znxP2O7 ceramics
(2013-10-29)
Sutapun, Manoon
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Muanghlua, Rangson
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Niemcharoen, Surasak
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Vittayakorn, Wanwilai C.
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Seeharaj, Panpailin
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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Phase transition behaviour and electrical properties of lead-free (K 0.5Na0.5)NbO3-LiNbO3-LiSbO 3 piezoelectric ceramics
(2011-05-01)
Muanghlua, Rangson
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Niemcharoen, Surasak
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Sutapun, Manoon
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Boonchom, Banjong
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Vittayakorn, Naratip
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 and dielectric properties of lead free (K 0.5Na0.5)NbO3- Bi(Zn0.5Ti 0.5)O3 piezoelectric ceramics
(2009-12-01)
Sutapun, Manoon
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Vittayakorn, Naratip
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 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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Vittayakorn, Naratip
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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