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Subject: search.filters.subject.dielectric property

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    Tailoring charge affinity, dielectric property, and band gap of bacterial cellulose paper by multifunctional Ti2NbO7 nanosheets for improving triboelectric nanogenerator performance
    (2023-02-01)
    Sriphan, Saichon
    ;
    Pharino, Utchawadee
    ;
    Charoonsuk, Thitirat
    ;
    Pulphol, Phieraya
    ;
    Pakawanit, Phakkhananan
    Transparent, flexible, and high-performance triboelectric nanogenerator (TENG) from nature-derived materials are required for sustainable society development. However, low triboelectricity from natural material is generally observed. Tunable electronic band diagram (EBD) through facile manipulation is one of the efficient methods to promote the TENG output, requiring fundamental, in depth understanding. Herein, we employed the high quality, single crystal-like Ti<inf>2</inf>NbO<inf>7</inf> nanosheets (NSs) with dual dielectric and semiconducting properties as filler for bacterial cellulose (BC)-based TENG. Several techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), ultraviolet—visible (UV—vis) absorption, energy dispersive X-ray spectroscopy (EDS), and synchrotron radiation X-ray tomographic microscopy (SRXTM) were applied to characterize the long-range structure, microstructure, optical properties, elemental composition, and three-dimensional (3D) distribution of components in the composites. The semi-transparent and flexible 5 vol.% Ti<inf>2</inf>NbO<inf>7</inf> NSs/BC preserved the integrity of cellulose, contained well-dispersed nanosheets, reduced optical band gap (4.20 vs. 5.75 eV for BC), and increased surface roughness. The dielectric permittivity and conductivity increased with nanosheets content. Adding negatively-charged Ti<inf>2</inf>NbO<inf>7</inf> NSs could regulate the charge affinity of BC composite via shifting of Fermi energy over that of Al. It is found that adding 5 vol.% NSs into the BC film improved electrical outputs (~ 36 V and ~ 8.8 µA), which are 2–4 times higher than that of pure BC, even when paired with Al which lies adjacent in triboelectric series. Our work demonstrated the method to enhance BC-based TENG performance through EBD regulation using multifunctional Ti<inf>2</inf>NbO<inf>7</inf> NSs. [Figure not available: see fulltext.]
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    Multifunctional Nanomaterials Modification of Cellulose Paper for Efficient Triboelectric Nanogenerators
    (2020-05-01)
    Sriphan, Saichon
    ;
    Charoonsuk, Thitirat
    ;
    Maluangnont, Tosapol
    ;
    Pakawanit, Phakkhananan
    ;
    Rojviriya, Catleya
    There is a need to develop inexpensive, lightweight, and flexible high-performance triboelectric nanogenerators (TENGs) from renewable resources. Here, a multifunctional cellulose filter paper (CFP)-based TENG consisting of dielectric Ti<inf>0.8</inf>O<inf>2</inf> nanosheets (Ti<inf>0.8</inf>O<inf>2</inf> NSs) and conducting Ag nanoparticles (Ag NPs) is prepared by a simple dip coating method. The incorporation of dielectric Ti<inf>0.8</inf>O<inf>2</inf> NSs onto the CFP significantly improves charge generation, while the inclusion of Ag NPs provides an electrically conductive path for charge transportation. The presence of these fillers can be deduced from XRD, SEM, EDS, X-ray photoelectron spectroscopy, and Raman spectroscopy. Their distribution is visualized in 3D by synchrotron radiation X-ray tomography. The present CFP-based TENG provides an output voltage and current density of ≈42 V and ≈1 µA cm<sup>−2</sup>, respectively with the power density of ≈25 µW cm<sup>−2</sup>. It is capable of lighting up 40 light-emitting diode bulbs and charging a 0.22 µF capacitor to 8 V in only 5 s. The developed TENG is also capable of detecting simple human motions, i.e., finger tapping, finger rubbing, and foot trampling. This work offers a facile design of low cost yet efficient paper-based TENG by dual modification with multifunctional nanomaterials, and also demonstrates its use as a feasible power source that not only drives small electronics, but also scavenges energy from human actions.
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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
    ;
    Yuennan, Jureeporn
    ;
    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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    Dielectric properties of nanocrystalline barium zirconate titanate synthesized by glycine-nitrate autocombustion
    (2019-01-02)
    Seeharaj, Panpailin
    ;
    Charoonsuk, Thitirat
    ;
    Vittayakorn, Naratip
    Dielectric properties of nanocrystalline barium zirconate titanate (Ba(Zr<inf>x</inf>Ti<inf>1-</inf><inf>x</inf>)O<inf>3</inf>; BZT for x = 0.1 and 0.3) synthesized by glycine-nitrate autocombustion method were investigated in this study. The phase formation examined by TGA-DTA, XRD, FT-IR and Raman spectroscopy confirmed that high purity single-phase BZT with perovskite structure was obtained by using glycine-to-nitrate molar ratio of 2.2:4 and calcining in air at 1100 °C for 4 h. TEM analysis showed that BZT had agglomerate particles consisted of primary spherical nanocrystals with the size of 8-11 nm. The diffuse phase transition behavior of BZT ceramics increased with increasing Zr concentration and for x = 0.3, the Curie temperature; T<inf>c</inf>, shifted to below room temperature. The BZT ceramics for x = 0.1 had relatively high dielectric constant (ε), 13007, low T<inf>c</inf>, 76 °C and comparable dielectric loss (tan δ) at T<inf>c</inf>, 0.012 which caused by the high degree of Zr diffuseness into the perovskite structure. These results suggest that glycine-nitrate autocombustion is the effective method for preparing high quality BZT ceramics.