Seeharaj, Panpailin

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Sonochemical synthesis of monodispersed perovskite barium zirconate (BaZrO3) by using an ethanol-water mixed solvent
(2015-07-01)
Charoonsuk, Thitirat
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Vittayakorn, Wanwilai
;
Vittayakorn, Naratip
;
Seeharaj, Panpailin
;
Maensiri, Santi
Perovskite barium zirconate (BaZrO<inf>3</inf>) was synthesized successfully in an ethanol-water mixed solvent under ultrasonic irradiation. Four compositions, including 0%, 30%, 50%, and 70% by volume of ethanol in ethanol/water mixed solvent, were used. The effect of ethanol content and irradiation time on the phase formation and morphology of product particles was studied and discussed. As a result, a pure perovskite BaZrO<inf>3</inf> phase was formed completely at a short irradiation time of about 15 min in 70% by volume of ethanol without the calcination process. The average particles size decreases and particle size distribution becomes narrower by increasing the percentage of ethanol volume. On the other hand, the monodispersibility of BaZrO<inf>3</inf> particles was improved significantly through ultrasonic irradiation.
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The role of γ-C2H5NO2 as a new transient liquid phase in cold sintering process of BaTiO3 composites
(2024-07-01)
Noisak, Jitrawan
;
Ieamviteevanich, Pimchanok
;
Charoonsuk, Thitirat
;
Pakawanit, Phakkhananan
;
Pinpru, Nattapong
Dielectric materials, such as barium titanate (BT)-based materials, have excellent dielectric properties but require high temperatures (above 1300 °C) for ceramic fabrication, leading to high costs and energy loss. The cold sintering process (CSP) offers a solution to these issues and is gaining worldwide attention as an innovative fabrication route. In this work, we proposed an alternative organic ferroelectric phase, gamma-glycine (γ-GC), which acts as a transient liquid phase to fabricate high-density composites with barium titanate (BT) at low temperatures through CSP. Our findings show that the density of 15γ-GC/85BT reached 96.7%±1.6% when it was sintered at 120 °C for 6 h under 10 MPa uniaxial pressure. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) mappings of the composite suggested that γ-GC completely underwent the precipitation–dissolution process and, therefore, filled between BT particles. Moreover, X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirmed the preservation of γ-GC without undesired phase transformation. In addition, the ferroelectric and dielectric properties of γ-GC/BT composites have been reported. The high dielectric constant (ε<inf>r</inf>) was 3600, and the low dielectric loss (tanδ) was 1.20 at 200 °C and 100 kHz for the 15γ-GC/85BT composite. The hysteresis loop showed a remanent polarization (P<inf>r</inf>) of 0.55 µC·cm-2 and a coercive field (E<inf>c</inf>) of 7.25 kV·cm-1. Our findings reaffirmed that an organic ferroelectric material (γ-GC) can act as a transient liquid phase in a CSP that can successfully and sustainably fabricate γ-GC/BT composites at low temperatures while delivering outstandingly high performance.
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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.
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Phase formation, microstructure, and densification of yttrium-doped barium zirconate prepared by the sonochemical method
(2016-01-01)
Seeharaj, Panpailin
;
Charoonsuk, Thitirat
;
Pasupong, Patchara
;
Kim-Lohsoontorn, Pattaraporn
;
Vittayakorn, Naratip
Spherical monodispersed yttrium-doped barium zirconate (BaY<inf>0.1</inf>Zr<inf>0.9</inf>O<inf>3</inf>; BYZ) particles were successfully prepared in single step without the requirement of calcination process by the sonochemical method in highly basic aqueous solution. The stoichiometric solution of BaCl<inf>2</inf>.2H<inf>2</inf>O, ZrOCl<inf>2</inf>.8H<inf>2</inf>O, and YCl<inf>4</inf>.6H<inf>2</inf>O was precipitated in a 20 M NaOH under high-intensity ultrasonic irradiation (20 kHz, 150 W/cm2) for 15, 30, and 60 min. As-prepared powders were identified by XRD, FT-IR, and Raman spectroscopy as cubic perovskite BYZ. The microstructure examined by SEM and TEM showed spherical-shaped BYZ particles formed by aggregation of primary nanocrystals, and this unique morphology was induced by the effects of the ultrasonication and the strong alkaline environment. BYZ powders prepared under ultrasonication for 60 min had narrow-sized distribution with the average particle size of 267 ± 26 nm and the specific surface area of 40.2 m2/g. BYZ ceramics sintered in the air at 1550°C for 20 h showed good densification (95%) and consisted of large grain size (7.67 ± 2.79 μm).

Seeharaj, Panpailin

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