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Effect of Annealing Time on the Cation Distribution in Mn Doped CoFe2O4
(2016-02-19)
Roongtao, Rachanusorn
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Vittayakorn, Naratip
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Klysubun, Wantana
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Vittayakorn, Wanwilai C.
In this work, the series of CoFe<inf>2</inf><inf>x</inf>Mn<inf>x</inf>O<inf>4</inf> powders were synthesized using the solid state method. The structure and lattice parameter of the samples were determined by the X-ray diffraction (XRD) and Rietveld refinement method. The morphology was confirmed without annealing and with annealing at 500°C for 4 and 100 h, with the samples examined by scanning electron microscopy (SEM). Then, the distribution of migrating cations was analyzed using X-ray absorption spectroscopy (XAS). Also, magnetic properties were examined by a vibrating sample magnetometer (VSM). It can be confirmed from the morphology that the average particle size before and after annealing remained unchanged, and ranged from 0.66 ± 0.20 m to 0.79 ± 0.26 m. Furthermore, the distribution of cations was no different after annealing Mn ions at 500°C for 100 h. However, the distribution of cations migrated to their site of preference after annealing Co and Fe ions in the structure. The result of migrations induced a saturated magnetization increase to 42.24 emu/g.
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Influence of Mn doping on the magnetic properties of CoFe2O 4
(2014-01-03)
Roongtao, Rachanusorn
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Baitahe, Rattanai
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Vittayakorn, Naratip
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Seeharaj, Panpailin
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Vittayakorn, Wanwilai C.
A series of CoFe<inf>2-x</inf>MnxO<inf>4</inf> ceramics were synthesized successfully by conventional solid state reaction. The X-ray diffraction analysis proved that all samples were found to have a cubic spinel structure. Diffractograms were used for Rietveld refinement to determine lattice parameters, of which lattice parameter increased with increasing Mn concentration. The microstructure of the samples was studied using scanning electron microscopy. The vibrating sample magnetometer measurements showed that the highest saturated magnetization of 118.11 emu/g and coercivity of 46.89 Oe were observed in CoFe<inf>1.85</inf>Mn<inf>0.15</inf>O<inf>4</inf> ceramic. Furthermore, X-ray absorption spectra of the samples were recorded to determine the Co, Fe and Mn valence states and their preferentially sites of the spinel structure. © 2014 Taylor and Francis Group, LLC.
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Fabrication and properties of BaTiO3-CoFe2O 4 nanocomposites
(2013-12-01)
Vittayakorn, Wanwilai C.
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Pulphol, Nattakarn
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Muanghlua, Rangson
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Vittayakorn, Naratip
In this work, BaTiO<inf>3</inf>-xCoFe<inf>2</inf>O<inf>4</inf>, where x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5, nanocomposites were prepared by conventional mixing method and followed by normal sintering in air. The effect of processing condition on phase formation, microstructure, magnetic and electrical properties of the BaTiO<inf>3</inf>-CoFe<inf>2</inf>O<inf>4</inf> nanocomposites was investigated. The phase development and microstructural evolution of this system have been determined via X-ray diffractometer and scanning electron microscope. From the results, it concludes that phase formation, microstructure, electrical and magnetic properties of the BaTiO<inf>3</inf>-xCoFe<inf>2</inf>O<inf>4</inf> nanocomposites strongly depend on chemical composition. © 2013 Copyright Taylor and Francis Group, LLC.
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Structural and magnetic properties of Zn doped CoFe2O 4
(2013-12-01)
Roongtao, Rachanusorn
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Baitahe, Rattanai
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Vittayakorn, Naratip
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Klysubun, Wantana
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Vittayakorn, Wanwilai C.
Zinc doped cobalt ferrite powders were prepared by the solid state reaction method. The effect of zinc substitution on structure, morphology and magnetic properties was investigated. The X-ray analysis confirmed existence of the single phase cubic spinel structure, while Rietveld refinement data showed increasing of lattice parameters with zinc content. In addition, saturated magnetization increased with increasing zinc concentration and it was contained at maximum in CoFe<inf>1.9</inf>Zn0.<inf>1</inf>O<inf>4</inf> powders. However, the value of coercivity was decreased with zinc doped content. Furthermore, the oxidative states were characterized by X-ray absorption spectroscopy. The results confirm that the structure contained Co2+, Fe3+ and Zn2+ ions. © 2013 Copyright Taylor and Francis Group, LLC.
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Processing and characterizations of Bi2O3/BaTiO3 ceramic
(2013-10-29)
Vittayakorn, Wanwilai C.
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Banjong, Dondanai
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Vittayakorn, Naratip
The objective of this work is to provide the process for making BaTiO<inf>3</inf>-based ceramics by adding bismuth oxide (Bi<inf>2</inf>O<inf>3</inf>) into the system. The attention is also focused on synthesis conditions, where sintering temperature exhibits a pronounced effect on phase formation, density, microstructure and dielectric properties of BaTiO3 ceramics doped with different contents of Bi<inf>2</inf>O<inf>3</inf> nanoparticles. The phases of BaTiO<inf>3</inf>-based ceramics have been prepared by solid state reaction using different Bi<inf>2</inf>O<inf>3</inf> amount and characterized by X-ray diffractometry, Archimedes's method, scanning electron microscopy and dielectric spectroscopy. The results show that single phase of BaTiO<inf>3</inf> with no evidence of secondary phase forms in all samples. Abnormal grain growth was found in pure BaTiO<inf>3</inf> ceramic with 37.30 μm of average grain size. After added Bi<inf>2</inf>O<inf>3</inf> nanoparticles into system, the grain size significantly decreases and the sintering temperature of BaTiO3-based ceramics efficiently reduces without degrading the dielectric characteristics. © (2013) 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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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 Zn2+ 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> 4- 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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Magnetoelectric properties of BaTiO3 - Co0.5Ni0.5Fe2o4 composites prepared by the conventional mixed oxide method
(2013-10-29)
Pulphol, Nattakarn
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Muanglua, Rangson
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Niemcharoen, Surasak
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Pecharapa, Wisanu
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Vittayakorn, Wanwilai C.
Multiferroics, which display simultaneous ferrimagnetic and ferroelectric properties, have been interesting recently because of their potentially significant applications in multifunctional devices such as magnetic resonance, drug delivery, high-density data storage, ferrofluid technology, etc. Composites combining BaTiO<inf>3</inf> with Co<inf>0.5</inf>Ni<inf>0.5</inf>Fe<inf>2</inf>O<inf>4</inf> have influenced the interest of many researchers, due to their outstanding and distinguished character called magnetoelectric (ME). In this work, ferrimagnetic-ferroelectric composites of BaTiO<inf>3</inf> nanopowder and Co<inf>0.5</inf>Ni<inf>0.5</inf>Fe<inf>2</inf>O<inf>4</inf> nanopowders were prepared by a conventional mixed oxide method. The multiferroic ceramics were compounded with the formula, (1-x)BaTiO<inf>3-</inf>(x) Co<inf>0.5</inf>Ni<inf>0.5</inf>Fe<inf>2</inf>O<inf>4</inf>, in which x = 0, 0.05, 0.10, 0.20 and 0.35. All of the compositions were analyzed by an X-ray diffractometer (XRD) in order to reveal the phase of perovskite and spinal structure. Scanning electron microscopy (SEM) was used to examine the variation of morphology and grain size of the composited ceramics. The magnetism of all the ceramics was measured using a vibrating sample magnetometer (VSM). The results showed that microstructure and the amount of ferrite are related strongly with magnetization. © (2013) Trans Tech Publications, Switzerland.
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Sonochemical synthesis of spherical BaTiO3 nanoparticles
(2013-01-01)
Vuttivong, Sirajit
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Niemcharoen, Surasak
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Seeharaj, Panpailin
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Vittayakorn, Wanwilai C.
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Vittayakorn, Naratip
Monosized spherical barium titanate (BaTiO<inf>3</inf>) nanoparticles have been synthesized successfully via sonochemical reaction. The as-synthesized BaTiO<inf>3</inf> nanoparticles were characterized using X-ray diffraction of powder, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The XRD pattern of BaTiO<inf>3</inf> particles, which were synthesized under irradiation of ultrasonic sound for 0.5 h, showed sharp diffraction peaks that corresponded to the cubic BaTiO<inf>3</inf> phase. Only a small amount of BaCO<inf>3</inf> contamination was present in the sample. The Raman active modes of the samples in this study were similar to the cubic phase of BaTiO<inf>3</inf>. The average diameter of sonochemical synthesized particles was ∼99.54 ± 18.25 nm. The synthesized BaTiO<inf>3</inf> nanoparticles were almost spherical. © 2013 Copyright Taylor and Francis Group, LLC.
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The influence of BMN addition on the phase formation, microstructure and dielectric property of BaTiO3 ceramic
(2013-01-01)
Vittayakorn, Wanwilai C.
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Pulphol, Nattakarn
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Roongtao, Rachanusorn
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Muanghlua, Rangson
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Vittayakorn, Naratip
Solid solutions of the (1-x)BT-xBMN system were prepared successfully by the solid state reaction method followed by normal sintering in air. The phase formation, microstructure and dielectric property of BT-BMN ceramics were investigated as a function of compositions. XRD results showed a single perovskite phase for all compositions. Cubic-tetragonal transformation was found after adding BMN into the system. SEM micrographs revealed two very different grain sizes in the ceramics, with compositions of x = 0.02, 0.03, 0.04 and 0.05. Fine grains indicated a cubic structure, whereas large ones indicated a tetragonal structure. Regarding the dielectric property, Curie temperature decreased with increasing BMN content, whereas the er value increased until the BMN content reached 3 mol% before dropping to a lower value. Copyright © 2013 Taylor & Francis Group, LLC.
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Synthesis and phase evolution of electrospun antiferroelectric lead zirconate (PbZrO3) nanofibers
(2012-08-01)
Nawanil, Chanisa
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Boomchom, Banjong
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Prachayawarakorn, Jutarat
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Vittayakorn, Wanwilai C.
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Vittayakorn, Naratip
Lead zirconate (PbZrO<inf>3</inf>; PZO) fibers were synthesized by the electrospinning method using a solution that contained 5 wt% poly(ethylene oxide) (PEO) in ethanol and a sol-gel solution of PZO. Some parameters varied, for example, the ratio between PEO and PZO, concentrations of the precursor solution, flow rate, and calcination temperature. The as-spun and calcined PZO/PEO composite fibers were characterized by TG-DTA, X-ray diffraction, FT-IR, SEM and TEM. PZO fibers were obtained successfully with a well-developed perovskite structure after as-spun PZO/PEO composite fibers were calcined using the PZO/PEO volume ratio of 10:3 at a PZO concentration of 1.0 M at 650 °C for 4 h. Stable nanofibers were produced with an average diameter of 300 ± 64 nm. Additionally, the PZO fibers showed a Curie temperature that rose by nearly 13 °C, when comparing with a normal PZO particle. © 2012 Elsevier B.V. All rights reserved.

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