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Synthesis of BaTiO3@TiO2-sheet Core-Shell Structured Nanocomposites
(2019-01-02)
Nawanil, Chanisa
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Panprom, Parinya
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Makcharoen, Worawut
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Khaosa-Ard, Krittanat
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Maluangnont, Tosapol
Core-shell structure nanocomposites have been of interest, as they can exhibit unique properties arising from the combination of peculiar characteristics of each component. In this research, core-shell structured nanocomposites, comprising barium titanate (BaTiO<inf>3</inf>; BT) nanoparticles as the core and titanate (TiO<inf>2</inf>) nanosheets as the shell, were prepared. The surface of barium titanate (BT) nanoparticles was modified chemically by hydrogen peroxide (H<inf>2</inf>O<inf>2</inf>) to create hydroxyl groups. TiO<inf>2</inf> nanosheets were deposited on the surface of the functionalized BT core, via alternate adsorption with oppositely charged polyelectrolyte poly(diallyl dimethylammonium) (PDDA) cations to produce an ultrathin TiO<inf>2</inf> shell layer that encapsulates BaTiO<inf>3</inf> nanoparticles. The structure of the core-shell particles was investigated in order to illustrate their formation mechanisms. Furthermore, this work reported the advance in utilizing a core-shell nanostructure to enhance relative permittivity and maintaining a low loss of polymer nanocomposites. A significant improvement in relative permittivity is attributed to the TiO<inf>2</inf> shell, which acts as polarizable dipoles and consequently enhances interfacial polarization. The results indicated that the structure of core-shell nanocomposites is attractive as a novel structural building block for fabricating novel materials and electronic devices.
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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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Maluangnont, Tosapol
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Vittayakorn, Wanwilai
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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Effect of surface treatment on electrical properties of barium titanate/carbon nanotube/polydimethylsiloxane nanocomposites
(2018-09-05)
Nawanil, C.
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Panprom, P.
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Khaosa-Ard, K.
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Makcharoen, W.
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Vittayakorn, N.
Piezoelectric-based polymer composite for flexible self-powered materials have been of interest. In this research, the effect of surface treatment on electrical properties of barium titanate/carbon nanotube/polydimethylsiloxane (BT/CNT/PDMS) composites has been studied for acquiring high performance materials. In the preparation of BT/CNT/PDMS nanocomposite, the surface of CNT and BT disperse phases were modified to introduce a functional groups. These chemical treatments devoted to improve the interfacial interactions and dispersion by introduce the strong interaction between BT, CNT and PDMS. The measured electrical outputs of the modified BT based nanocomposites showed higher output voltage than the normal composite. It is indicates that the strong interaction between fillers and polymer matrix is the important factor to improved electrical properties of the composites. Furthermore, the results also shown an enhancement of relative permittivity and maintaining a low loss of polymer nanocomposites, which indicates 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.
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Dielectric properties of natural ester based nanofluid
(2017-11-29)
Jariyanurat, K.
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Potivejkul, S.
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Pattanadech, N.
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Chotigo, S.
In this paper, AC breakdown and standard impulse breakdown characteristics of natural ester oil and natural ester base nano fluids are investigated. Three types of nanoparticles such as Zinc oxide (ZnO), Barium titanate (BaTiO3), and Titanium dioxide (TiO2) which have their diameter less than 100 nm are used to prepare the nanofluid samples which consist of the natural ester mixed with 0.01% volume fraction of each nanoparticle type. To measure AC breakdown voltage of the natural ester and natural ester based nanofluids, the oil breakdown tester (FOSTER OTS 60AF) is employed by sphere-sphere electrode system according to IEC 60156. The gap distance between electrodes is set at 2.5 mm. Furthermore, the needle-sphere electrode configuration with gap spacing of 40 mm is used for impulse breakdown voltage investigation of the dielectric liquids by the needle is tungsten and 40 μ m tip radius. The test circuit is set up in accordance with IEC 60897 and the test experiment is conducted at room temperature. The test results show that the AC breakdown voltages of the natural ester with nanopaticles is markedly higher than those of the unmodified natural ester. Additionally, TiO2, BaTiO3, and ZnO nanoparticles show their properties to increase impulse breakdown voltages of the nanofluids compared with those of the unmodified natural ester. From the test results, it is found that nanoparticles are good candidates to enhance the dielectric properties of natural ester for dielectric applications.
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A facile one step conversion of the sub-micrometer to uniform nanopowder in tetragonal BaTiO3 via a surface active etching salt
(2016-11-15)
Charoonsuk, Thitirat
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Vittayakorn, Naratip
A reasonable design of nanoscale ferroelectric ceramic fillers, with well-controlled shape and size, has become very interesting in modern energy storage applications. A convenient “top-down” process was proposed to obtain nanoparticle products of tetragonal barium titanate (BaTiO<inf>3</inf>) with highly accurate stoichiometry and morphological control. The key point of this work emphasized that a micrometer-sized precursor decreases to nanometer-sized product particles, and its irregular shape changes to nearly spherical with narrow size distribution. Both XRD and Raman results of BaTiO<inf>3</inf> nanoparticles indicated a tetragonal crystal structure. The 77.5 ± 2.5 nm sized BaTiO<inf>3</inf> powder product still polarized spontaneously at room temperature and the ferroelectric phase transition was confirmed at around 127 °C. Dielectric permittivity was found to be ~ 166.42 by Landauer-Bruggeman effective medium approximation (LB-RMA). Experimental procedures revealed a possible process mechanism observed within the etched surface and Oriented-attachment growth models, and this demonstrated approach could be used as an excellent platform for preparing ceramic nanoparticles. It also could be extended to synthesize complex oxide of functional materials for the preparation of other ceramic/polymer-based nanocomposites that achieve desirable properties.
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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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Characterization and properties of BaTi3O3/MgO nanocomposite ceramics
(2011-12-19)
Vittayakorn, W. C.
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Bunjong, D.
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Muanghlua, R.
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Vittayakorn, N.
In this research, BaTiO<inf>3</inf>./xMgO nanocomposite ceramics, where x = 0, 0.3, 0.5, 0.7 and 1.0 vol%, were prepared by a mixedoxide method. The effect of MgO additions on the phase formation, microstructure and dielectric properties of this system was investigated via X-ray diffraction (XRD), scanning electron microscopy (SEM) and dielectric spectroscopy, respectively. From the results, XRD analysis showed that there is no unwanted phase except BaTiO <inf>3</inf> and MgO observed in these ceramics. Abnormal grain growth was found in pure BaTiO<inf>3</inf> ceramic with a 75.32 μm average grain size. After adding MgO nanoparticles into the system, the grain size significantly decreased to 0.55 μm and continuously decreased with increasing MgO content. For the dielectric properties, the pure BT ceramic exhibits a sharp and high dielectric peak whereas a low and broad peak is found in BT/MgO nanocomposite ceramics, which can be explained by the composite structure.

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