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Point Defects in Rare-Earth Perovskite Systems BaMO3 (M = Ce, Pr and Tb) on Dielectric and Magnetic Behaviors
(2023-01-01)
Pulphol, Phieraya
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Tariwong, Yaowaluk
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Charoonsuk, Thitirat
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Maluangnont, Tosapol
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Vittayakorn, Wanwilai
This study focused on the rare-earth hetero-valent substituted perovskite BaMO<inf>3</inf> (M = Ce, Pr and Tb) which expected to show magnetoelectric response. In general, diamagnetic feature is presented in the 4f 0 BaCeO<inf>3</inf> system down to 2 K which is chosen as a reference in the study while BaPrO<inf>3</inf> (4f 1) and BaTbO<inf>3</inf> (4f 7) display antiferromagnetic phase transition at T<inf>N</inf> = 11.7 and 33.2 K, respectively, measured by MPMS magnetometer. At high oxygen partial pressure and donor ion-substitution (Nb5+), the BaMO<inf>3</inf> systems demonstrate a similar defect chemistry to titanate perovskite which compensated by Ba-vacancy. Dielectric relaxation is detected for the doublet (BaPrO<inf>3</inf> and BaTbO<inf>3</inf>) at the antiferromagnetic phase transition region. In order to examine the magnetoelectric response, the 8 Tesla of magnetic field is applied to the samples during the dielectric measurement. BaTbO<inf>3</inf> shows a modest magnetoelectric response around 0.2% at the antiferromagnetic phase transition while that of BaPrO<inf>3</inf> is silent. The activation energies derived from Arrhenius equation are reported to be in the range of 0.2 − 0.6 eV.
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Intrinsic Enhancement of Permittivity with Ultralow Dielectric Loss in Donor-Acceptor Co-Doped Rutile TiO2 Ceramics
(2021-01-01)
Pulphol, Phieraya
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Pongampai, Satana
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Charoonsuk, Thitirat
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Vittayakorn, Wanwilai
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Muanghua, Rangson
The immense potential of colossal dielectric materials for use in high-energy-density storage applications has driven much recent development and research. The discovering of such dielectric materials with the required high permittivity and low dielectric loss is still a highly challenging. Herein, the donor-acceptor co-doped TiO<inf>2</inf> has been developed based on (Mg<inf>0.5</inf>W<inf>0.5</inf>) <inf>x</inf> Ti<inf>1-</inf><inf>x</inf> O<inf>2</inf>, (In<inf>0.5</inf>W<inf>0.5</inf>) <inf>x</inf> Ti<inf>1-</inf><inf>x</inf> O<inf>2</inf> and (Ni<inf>0.5</inf>Nb<inf>0.5</inf>) <inf>x</inf> Ti<inf>1-</inf><inf>x</inf> O<inf>2</inf>; where x = 0.005–0.01, that manifests high permittivity (>104). The resulted permittivity attains the quadruple than that of pure TiO<inf>2</inf> ceramic with low dielectric loss of ∼0.02 over a broad temperature range. This performance is corresponded to the electron-pinned defect-dipoles, providing the extra dielectric response to those of rutile TiO<inf>2</inf> host ceramics. This research offers the way to develop functional colossal-dielectric materials by engineering complex defects into the bulk that will help for further discovery of promising new dielectric materials in future.
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Water Repellent Modified Polyester Fabric Based Triboelectric Nanogenerator for Harvesting Human Mechanical Energies
(2021-01-01)
Pharino, Utchawadee
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Ausaman, Kanyamon
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Phonimdang, Kunyapak
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Pongampai, Satana
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Vittayakorn, Wanwilai
Wearable triboelectric nanogenerators (TENGs) for converting human mechanical energies into electricity are being investigated widely, because of their potentially diverse applications that come from wearable power supplied to multifunctional self-powered sensing. However, external influences, such as water or high humidity, seriously degrade the electrical output of TENGs. Therefore, a simple method was implemented for fabricating a water repellent fabric-based TENG for harvesting human mechanical energies. Polytetrafluoroethylene (PTFE) or SiO<inf>2</inf> modified by trichloro(octadecyl)silane (OTS) were sprayed onto a polyester (PET) fabric surface to increase hydrophobicity. The PTFE and SiO<inf>2</inf>/OTS coated polyester fabrics exhibited excellent water repellency with a high-water contact angle of ∼144° and ∼153°, respectively. The surface morphology of the coated fabrics showed roughness with a granular structure, which was responsible for air entrapment that prevented water from penetrating the fabric. Furthermore, electrical output of conventional PET fabric-based TENG was found to improve with the deposition of PTFE particles on the fabric surface. By pairing the PTFE coated fabric with aluminum (Al) tape, in order to fabricate TENG, the device generated a maximum voltage of 10.2 V and short-circuit current of 0.20 µA, with a power output of 0.23 (Formula presented.) W/cm2, which is 14 times greater than that of SiO<inf>2</inf>/OTS coated fabric-based TENG. The process for achieving water repellent fabric is simple, and the coating materials are available. Thus, a water repellent fabric-based TENG is promising for large-scale production of wearable harvesters from power supplied to multifunctional self-powered sensing.
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The effect of thai glutinous rice starch on the synthesis of lead zirconate (PbZrO3) nanofibers via the electrospinning method
(2013-05-01)
Nawanil, Chanisa
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Vittayakorn, Wanwilai
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Muanghua, Rangson
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Niemcharoen, Surasak
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Prachayawarakorn, Jutarat
This study synthesized blended lead zirconate (PbZrO<inf>3</inf>;PZ)/ poly(ethylene oxide)(PEO)/Glutinous rice starch (GRS) nanofibers by the electrospinning method. A number of parameters such as the ratio between PEO and GRS and calcination temperature have been studied. The as-spun PZ/PEO/GRS composite and PZ fibers were characterized by TG-DTA, X-ray diffraction, FT-IR and SEM, respectively. SEM results showed that smooth and continuous fibers were obtained at the volume ratio of 10:2:1, PZ/PEO/GRS. After calcination of the as-spun PZ/PEO/GRS composite nanofibers at 650 °C for 4 h, PZ nanofibers with perovskite structure were obtained successfully. The fibers had a uniform and smooth surface without grain boundaries. However, when the calcination temperature increased to 750 °C and 850 °C, the fiber represented a necklace-like structure with grain boundaries arranged by grain to grain unit cell clusters. Copyright © 2013 American Scientific Publishers.
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Synthesis of monodispersed perovskite barium zirconate (BaZrO3) by the sonochemical method
(2013-01-01)
Charoonsuk, Piyanut
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Baitahe, Rattanai
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Vittayakorn, Wanwilai
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Atiwongsangthong, Narin
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Muanghua, Rangson
Barium zirconate (BaZrO<inf>3</inf>) was synthesized successfully by the sonochemical method. The monophase of BaZrO<inf>3</inf> was formed completely in short irradiation time without the calcination process. X-ray diffraction, Fourier transform and Raman spectroscopy were used to characterize formation of the perovskite BaZrO<inf>3</inf> phase, which occurs in a 60 minute single phase with a cubic crystal structure at room temperature. Therefore, sonochemical irradiation could accelerate the formation of BaZrO<inf>3</inf> particles significantly. Furthermore, scanning electron microscopy investigated the uniform shape and size. The size distribution became narrow with increasing time, as a function of irradiation. © 2013 Copyright Taylor and Francis Group, LLC.

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