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Energy conversion capacity of barium zirconate titanate
(2020-01-01)
Binhayeeniyi, Nawal
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Sukwisute, Pisan
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Nawae, Safitree
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Muensit, Nantakan
In this study, we investigated the effect of zirconium content on lead-free barium zirconate titanate (BZT) (Ba(Zr<inf>x</inf>Ti<inf>1-x</inf>)O<inf>3</inf>, with x = 0.00, 0.01, 0.03, 0.05, and 0.08), which was prepared by the sol-gel method. A single-phase perovskite BZT was obtained under calcination and sintering conditions at 1100 °C and 1300 °C. Ferroelectric measurements revealed that the Curie temperature of BaTiO<inf>3</inf> was 399 K, and the transition temperature decreased with increasing zirconium content. At the Curie temperature, Ba(Zr<inf>0.03</inf>Ti<inf>0.97</inf>)O<inf>3</inf> with a dielectric constant of 19,600 showed the best performance in converting supplied mechanical vibration into electrical power. The experiments focused on piezoelectric activity at a low vibrating frequency, and the output power that dissipated from the BZT system at 15 Hz was 2.47 nW (30 MΩ). The prepared lead-free sol-gel BZT is promising for energy-harvesting applications considering that the normal frequencies of ambient vibration sources are less than 100 Hz.
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Mechanical, dielectric, thermal and antibacterial properties of reduced graphene oxide (rGO)-nanosized C3AH6 cement nanocomposites for smart cement-based materials
(2019-10-15)
Phrompet, Chaiwat
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Sriwong, Chaval
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Ruttanapun, Chesta
This work aimed to fabricate nanocomposites of reduced graphene oxide (rGO)-nanosized C3AH6 cement via a rapid cement hydration for enhancing its micro-hardness, dielectric constant, thermal conductivity, electrochemical and antibacterial properties.rGO-nanosized C3AH6 nanocomposites (∼10–20 nm in diameter) with 1, 2, 3, and 4% weight of rGO, were successfully synthesized from a Ca12Al14O33 and rGO colloid that was rapidly heated with water to a temperature of 100 °C. Nanocomposites of x%rGO-C3AH6 (x = 1, 2, 3, and 4) were characterized using XRD, UV–vis spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and TGA techniques. The chemical composition was confirmed using SEM and EDX characterization. The results revealed a nanocomposited rGO-C3AH6 material with nanosheet and nanoflaked rGO, as well as nanosized C3AH6 particles. The results presented rGO-C3AH6 with high performance multifunctional properties that included enhanced mechanical, dielectric, and thermal properties. The vickers micro-hardness and dielectric constant were enhanced by the effect of rGO-C3AH6 nanocomposites. The thermal conductivity of rGO-C3AH6 was higher than that of C3AH6. The electrical conductivity and electrochemical properties were effectively increased with greater levels of rGO in the material. Its antibacterial activity was confirmed by the formation of clearing zones on a Petri plate seeded with Escherichia coli (E. coli). The diameter of these zones increased with the rGO content. These results confirmed that nanocomposited rGO-C3AH6 was effective in enhancing mechanical, dielectric and thermal properties while serving as a high performance multifunctional cement-based material.
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Morphology and dielectric investigations of hydrated-halt P(VDF-HFP) membranes
(2017-01-01)
Yuennan, J.
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Sukwisute, P.
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Muensit, N.
This study focuses on a preparation and characterization of hydrated-salt membranes based on the blend of poly(vinylidene fluoride-hexafluoropropylene) [P(VDF-HFP)] and magnesium chloride (MgCl<inf>2</inf>·6H<inf>2</inf>O). The membranes with MgCl<inf>2</inf>·6H<inf>2</inf>O concentration of 0-4 wt% were prepared by solution casting technique. An elemental composition of the prepared samples was analyzed using energy dispersive x-ray spectroscopy (EDS). The surface morphology and pore size of these membranes were investigated by scanning electron microscopy (SEM). Surface roughness of the as-received membranes was evaluated by atomic force microscopy (AFM). The degree of the crystallinity and phase structures of the P(VDF-HFP) membranes were analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The dielectric and the electrical conductivity of all samples were measured in a range of 1-10<sup>5</sup> Hz. The SEM and AFM images revealed that the formation of the microporous P(VDF-HFP) membranes was controllable by the adjustment of MgCl<inf>2</inf>·6H<inf>2</inf>O content. The surface roughness, pore size and ionic conductivity of the as-received membranes increased with MgCl<inf>2</inf>·6H<inf>2</inf>O concentration. The dielectric constant reached its maximum value of about 25 at 3.5 wt% of MgCl<inf>2</inf>·6H<inf>2</inf>O. The XRD results showed that the mixture of MgCl<inf>2</inf>·6H<inf>2</inf>O salt led to a decrease in the degree of crystallinity. However, the salt-loaded P(VDF-HFP) enhanced the fraction of an electroactive β-phase up to 84% and this was confirmed by the FTIR results. This pointed out that the hydrated-salt P(VDF-HFP) membranes had a potential in new applications such as energy harvesting area.
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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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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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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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