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Triboelectric Nanogenerator Prepared from Poly(vinylidene Fluoride-Hexafluoropropylene) Polymer Composite
(2023-01-01)
Wannarumon, Pattarasuda
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Limsuwan, Pichet
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Sukwisute, Pisan
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Somdock, Nuttakrit
In this work, poly(vinylidene fluoride-hexafluoropropylene)/reduced graphene oxide films were prepared by the solution casting method with N,N-dimethylformamide (DMF) and DMF/acetone mixed solvents. The effects of reduced graphene oxide and solvent type on the morphology and crystal structure of the composite films were investigated by using scanning electron microscopy, Fourier-transform infrared spectroscopy, and Raman spectroscopy, respectively. The morphology study showed that the addition of acetone in the film process resulted in the occurrence of tiny pores on the film surfaces. The reduced graphene oxide incorporated into the PVDF-HFP was able to promote the formation of β- phase in the composites. The maximum power of 15.58 µW was obtained from the films using DMF/acetone mixture as solvent.
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Simultaneous Seebeck coefficient and electrical conductivity enhancement of GeSbTe films via Sn addition
(2022-06-15)
Khwansungnoen, Phalakorn
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Daichakomphu, Noppanut
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Sukwisute, Pisan
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Limsuwan, Pichet
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Somdock, Nuttakrit
Sn-added GeSbTe (GST) thin films were deposited using a co-magnetron sputtering technique. The effects of varying the Sn content through a variable Sn target sputtering power and post annealing at 673 K were investigated. The DC power density applied to the GST target was controlled at 50 W, while the power density of the Sn target was increased from 0 W to 40 W. The results demonstrate the coexistence of the fcc-GST, hcp-GST and SnTe phases in the Sn-added GST thin films. The substitution of Sn at the Ge-site increases the crystallization speed and leads to defects and lattice disordered local arrangement in the GST films, causing the Seebeck coefficient to increase. The SnTe phase was created as a result of the high Sn content in the sample due to the over-doping limit of Sn into the GST structure. The presence of SnTe in Sn-doped GST films increased the electrical conductivity. The maximum power factor of 17.0 μW/cmK2 at 450 K was obtained at an Sn content of 14.7 at%. These results indicated that the thermoelectric properties of Sn-doped GST films were improved via the formation of an appropriate amount of SnTe composite.
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Improving the thermoelectric properties of thick Sb2Te3 film via Cu doping and annealing deposited by DC magnetron sputtering using a mosaic target
(2021-11-01)
Theekhasuk, Nattharika
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Sakdanuphab, Rachsak
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Nuthongkum, Pilaipon
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Pluengphon, Prayoonsak
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Harnwunggmoung, Adul
Thick Cu-doped Sb<inf>2</inf>Te<inf>3</inf> films were deposited on flexible substrate by DC magnetron sputtering from a mosaic Cu–Sb<inf>2</inf>Te<inf>3</inf> target. The Cu-doped Sb<inf>2</inf>Te<inf>3</inf> films were vacuum annealed to improve their thermoelectric properties. Density functional theory was used to clarify the internal mechanism of the Cu doped into the Sb<inf>2</inf>Te<inf>3</inf> system. The results showed that Cu substitution on a Sb site induced electronic states or impurity peaks of Sb<inf>2</inf>Te<inf>3</inf> at a valence band maximum. The carrier concentration of the Cu-doped Sb<inf>2</inf>Te<inf>3</inf> films increased as the Cu-doped concentration increased. However, the crystallite size and Seebeck coefficient of the Cu-doped Sb<inf>2</inf>Te<inf>3</inf> films decreased as the Cu-doped concentration increased. Post-annealing treatment improved the microstructure and thermoelectric properties of the Cu-doped Sb<inf>2</inf>Te<inf>3</inf> films. The maximum electrical conductivity and power factor values of 754.20 S/cm at 50 °C and 1.56 10−3 W/mK2 at 100 °C were obtained in the annealed film with a Cu-doped concentration of 3 at%.
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Energy-saving synthesis and β-phase enhancement of Cu2Se thermoelectric materials via the microwave hybrid heating technique
(2021-10-25)
Rudradawong, Chalermpol
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Sukwisute, Pisan
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Limsuwan, Pichet
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Harnwunggmoung, Adul
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Horprathum, Mati
Thermoelectric generators harvest energy from waste heat and convert it to electricity. β-Cu<inf>2</inf>Se is a candidate for them due to its outstanding thermoelectric properties and its environmentally friendly component elements. A microwave hybrid heating (MHH) method was used for the fast synthesis and enhancement of β-Cu<inf>2</inf>Se materials. The effects of the MHH reaction time on the phase microstructure and thermoelectric properties of the Cu<inf>2</inf>Se material were investigated, and the MHH method was compared with the conventional heating method. The X-ray diffraction patterns of samples, synthesized via the MHH method, showed monoclinic- (α) and cubic- (β) Cu<inf>2</inf>Se crystalline structures, whereas a single monoclinic-(α) structure was identified in a sample, synthesized via a conventional heating method. In addition, the β-Cu<inf>2</inf>Se phase was enhanced with increased MHH reaction time. The carrier concentration increased with β-Cu<inf>2</inf>Se content, which increased electrical conductivity and decreased the Seebeck coefficient. The Cu+ ions in the β-Cu<inf>2</inf>Se phase led to the reduced thermal conductivity. A low thermal conductivity of 0.86 W m−1 K−1 and a maximum dimensionless figure of merit of 0.32 at 523 K were realized for 10 min MHH sample. Finally, MHH showed very low energy consumption and saved time, which are essential for industrialization.
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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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Excited Discrete Force for Piezo Generator Undergone Ultra-Low Vibrations on Air-Compressor and Possible Application
(2019-04-22)
Thainiramit, Panu
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Wahab, Yufridin
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Techato, Kua Anan
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Sukwisute, Pisan
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Muensit, Nantakan
The number of residential buildings in many countries has been fast growing. Comfortable furniture and smart peripheral devices become common for well living in daily life. For example, an electronic wireless switch could be controlled via a mobile phone to open or close home appliances (i.e. light, air-conditioner, security and alarm system), it is so-called »Home Appliances Control». This paper demonstrated a simple-wireless standalone system for the case of the receiver module attached to the compressor unit of the conventional air conditioner. This research proposed an air-compressor as a source of discrete excitations and employed a conventional buzzer as a transducer. The vibration is harvested its mechanical energy to electricity by using a cantilever-type structure glued with the piezoelectric buzzer. The output energy is stored in capacitors thus being consequent as a miniature generator; then, the transmitted data is received by a wireless receiver from the remote transmitter. These result confirmed that the simple cantilever could act as a charger for the connected capacitors which was subsequently an energy source to feed wireless units. In this work, a running air-conditioner produced a charging cycle to capacitors of 3,150 μF within 1 hour. This is sufficient to send and receive the data of atmospheric temperature around the building. This application is useful as a warning sign for inhabitants.
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Enhancement of ferroelectric phase and dielectric properties of P(VDF-HFP) by NiCl2⋅6H2O nucleating agent
(2019-01-02)
Sukwisute, Pisan
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Yuennan, Jureeporn
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Muensit, Nantakan
This work focuses on an improvement of dielectric properties of poly(vinylidene fluoride-co-hexafluoropropylene) or P(VDF-HFP) via mixing with different nickel(II) chloride hexahydrate (NiCl<inf>2</inf>⋅6H<inf>2</inf>O) contents (0–2 wt%). The nanocomposite films have been prepared by a conventional solution technique. The results reveal that the surface roughness increases with increasing salt content. The NiCl<inf>2</inf>⋅6H<inf>2</inf>O salt has no significant effect on the crystallinity of films. Additional incorporation of NiCl<inf>2</inf>⋅6H<inf>2</inf>O in the polymer leads to the growing conductivity. However, the considerable enhancement in dielectric constant with the relatively low dielectric loss tangent (0.1–0.3) can be found because of the formation of β-phase nucleation of NiCl<inf>2</inf>⋅6H<inf>2</inf>O in the P(VDF-HFP) matrix. The maximum value of calculated β-phase fraction of the nanocomposite is achieved 86% for salt content 0.5 wt%. Moreover, the largest dielectric constant (29.2 at 10 Hz) of the film doped 2 wt% NiCl<inf>2</inf>⋅6H<inf>2</inf>O is about 7 times greater than that of the pure P(VDF-HFP). The findings in this research suggest that the NiCl<inf>2</inf>⋅6H<inf>2</inf>O/P(VDF-HFP) nanocomposite is a candidate dielectric material for the next generation of energy conversion components.
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Effect of hydrated salts on the microstructure and phase transformation of poly(vinylidenefluoride-hexafluoropropylene) composites
(2018-05-01)
Yuennan, Jureeporn
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Sukwisute, Pisan
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Muensit, Nantakan
The present work has investigated a means of fabricating porous, β phase P(VDF-HFP) film by adding two kinds of hydrated metal salts. Without the use of mechanical stretching or electrical poling treatments, MgCl<inf>2</inf> •6H<inf>2</inf>O and AlCl<inf>3</inf> •6H<inf>2</inf>O are found to induce the formation of β phase crystals in porous film derived from the solution casting method. Trivalent Al ions have been found to effectively promote the self-oriented β phase of the P(VDF-HFP) film greater than divalent Mg ions. The overall β content is achieved about 38% and 42% for adding 0.25 wt% Mg- and Al-salts, respectively. The average pore sizes and surface roughness of porous P(VDF-HFP) films are increased with increasing salt concentration. The dielectric constant of about 5 for pure P(VDF-HFP) film (at 100 Hz) has been boosted up to 13-19 when adding the salts. In addition, the P(VDF-HFP) films filled with Al-salt exhibit the largest piezoelectric coefficient of 20 pC/N. Thus, the modified polymers are one of candidate materials for using in dielectric and piezoelectric applications.

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