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    Effect of calcination temperatures on microstructure and phase formation of Ba(Zr0.25Ti0.75)O3 powders
    (2008-12-01)
    Bongkarn, T.
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    Phungjitt, N.
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    In this work, the effect of calcination temperatures on the microstructure and phase formation of Ba(Zr<inf>0.25</inf>Ti<inf>0.75</inf>)O<inf>3</inf> (BZT) powders were investigated. The BZT powders were prepared via the solid state reaction method under various calcination temperatures. It was found that the second phases such as BaCO<inf>3</inf> ZrO<inf>2</inf>, BaZrO<inf>3</inf> and Ba<inf>2</inf>ZrO<inf>4</inf> existed in samples with calcination temperature below 1200 °C. Homogeneity and a highly pure perovskite phase of the BZT powders were obtained with calcination condition at 1300 °C for 4 h. Lattice parameter a and the percentage of cubic perovskite phase tended to increase with increasing calcination temperatures. The TG-DTA results corresponded to the XRD investigation. The microstructures of calcined powders exhibited an almost-spherical morphology and had a porous agglomerated form in all samples. The average particle sizes were increased from 0.2 to 1.1 μm when calcination temperatures were increased from 800 to 1350 °C. © 2008 Trans Tech Publications, Switzerland.
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    Oxidation Kinetics of Soot on Acicular Mullite Membrane Filter Using Electron Microscopy and Thermogravimetric Analysis
    (2020-12-01)
    Saenkhumvong, Eakkawut
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    ; ; ;
    Hanamura, Katsunori
    This paper investigates the oxidation kinetics of carbon black on acicular mullite using thermogravimetric (TGA) and mullite microstructures by scanning electron microscopy (SEM) for the development of diesel particulate filters (DPFs). It is observed that the amount of each chemical composition strongly affects the structure of mullite. The addition of AlF<inf>3</inf> and V<inf>2</inf>O<inf>5</inf> to mullite promotes the growth of needle-shaped mullite crystals. Thermogravimetric analysis was used to investigate and characterize chemical kinetics of soot oxidation for better understanding of designs and configurations of diesel particulate filters. The mass conversion of soot on the acicular mullite (ACM) is oxidized faster than that on the mullite (ML) membrane at all temperatures examined. The calculation of apparent activation energy (E<inf>a</inf>) of soot oxidation with isothermal methods on mullite was presented. The results showed that activation energy of soot oxidation is enhanced with ACM than with ML at all temperatures examined. The average calculated apparent activation energy of soot oxidation on ACM and ML are 146.4 kJ/mole and 155.3 kJ/mole, respectively.
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    PHASE FORMATION AND ELECTRICAL PROPERTIES OF Ba0.91Ca0.09Ti0.916Sn0.084O3-0.1WT%ZnO -0.1WT%MnO2 LEAD-FREE FERROELECTRIC CERAMICS SYNTHESIZED VIA THE SOLID-STATE COMBUSTION METHOD
    (2025-01-01)
    Yimsabai, Sununta
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    Somsri, Widchaya
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    Charoenthai, Nipaphat
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    Suthapintu, Aekasit
    This work investigated the effect of firing temperatures on the phase formation, microstructure, and electrical properties of Ba0.91Ca0.09Ti0.916Sn0.084O3-0.1wt%ZnO-0.1wt%MnO2 (BCTS-ZnMn) lead-free ferroelectric ceramics synthesized via the solid-state combustion method. Glycine was used as fuel to reduce the synthesis temperature. The samples were calcined at temperatures from 1050 to 1250°C (in 50°C increments) for 3 h and sintered from 1250 to 1450°C (in 50°C increments) for 3 h. A pure perovskite phase was found in the powders calcined above 1100°C. The phase structure, microstructure, dielectric and ferroelectric properties of the ceramics were examined. The X-ray diffraction (XRD) analysis for the ceramics revealed the presence of tetragonal (T) and orthorhombic (O) phases in all the ceramics. The average particle size and average grain size increased with increasing firing temperatures. The density, dielectric constant at the Curie temperature (ɛc), Pr and Ps tended to increase with increasing sintering temperatures, up to 1400°C, and then decreased at 1450°C. The ceramic sintered at 1400°C exhibited the highest density (5.89 g/cm3), dielectric response (ɛc = 13324) and good ferroelectric behavior (Pr = 8.67 μC/cm2, Ps = 17.92 μC/cm2 and Ec = 0.99 kV/cm).
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    ADSORPTION OF HEAVY METALS USING BIO-CALCIUM CARBONATE DERIVED FROM A GOLDEN APPLE SNAIL (GAS) SHELL
    (2023-01-01)
    Panpho, Phakakorn
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    Kaewmud, Ketkanok
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    Sumang, Rattiphorn
    In this research studied the use of calcium carbonate (CaCO<sup>3</sup>) from golden apple snail (GAS) shells for application as an absorbent material to remove heavy metals in water sources, which replaces commercial calcium carbonate (CaCO<sup>3</sup>) to reduce production costs and increase waste value. The adsorption of heavy metal contents (such as lead; Pb and Cadmium; Cd), phase formation, and physical characterization of golden apple snail shells were investigated for use as a calcium source in the production of naturally based biomaterials. The samples were calcined between 700°C and 950°C for 5 hr. TG and DTA analysis of samples demonstrated the decomposition of CaCO<sup>3</sup> to CaO. The XRD results demonstrated that natural shell powder has a crystal phase of CaCO<sup>3</sup> with an aragonite structure. Furthermore, the CaCO<sup>3</sup> (calcite phase) was transformed into calcium oxide (CaO) as a component, which showed that the phase transformation depended on the calcination temperature. The adsorption experiments showed good performance at about 99.6%, 99.7%, and 97% removal efficiency in a shorter time for calcined GAS at 700, 800, and 900°C, respectively. This study suggests that the golden apple snail shell could be an effective biomaterial for heavy removal from contaminated water.
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    Effect of firing temperatures on phase formation and microstructure of Ba(Zr0.3Ti0.7)O3 ceramics prepared via mixed oxide method
    (2009-12-01)
    Bongkarn, Theerachai
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    Phungjitt, Nalinee
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    Ba(Zr0.3Ti0.7)O3 (BZT) ceramics were fabricated by a mixed oxide synthetic route. The effect of calcination and sintering temperatures on phase formation and the microstructure of the ceramics were investigated. The pure perovskite phase of BZT powders was obtained with a calcination condition of 1300°C for 4 h. The sintered pellets showed a pure peroverskite cubic phase in all samples. The microstructure of the powders exhibited an almost-spherical morphology and had a porous agglomerated form. The average particle sizes and the average grain sizes were increased from 0.2 to 1.1 μm and 3.9 to 25.1 μm with increasing calcination and sintering temperatures, respectively. The densest and the highest maximum dielectric constant was found in the BZT ceramic sintered at 1550°C. Copyright © Taylor & Francis Group, LLC.
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    ELECTRIC AND MAGNETIC PROPERTIES OF Ni0.475Zn0.475Li0.025Al0.025Fe2O4 DOPED (Bi0.5Na0.5)0.94Ba0.06TiO3 CERAMICS PREPARED BY THE SOLID-STATE COMBUSTION METHOD
    (2025-01-01)
    Pattanakasem, Wiwat
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    Sookboon, Chirarat
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    Somsri, Widchaya
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    Pinitsoontorn, Supree
    In this study, we synthesized (1-x)((Bi<inf>0.5</inf>Na<inf>0.5</inf>)<inf>0.94</inf>Ba<inf>0.06</inf>TiO<inf>3</inf>)-x Ni<inf>0.475</inf>Zn<inf>0.475</inf>Li<inf>0.025</inf>Al<inf>0.025</inf>Fe<inf>2</inf>O<inf>4</inf> [(1-x)BNBT-xNZLAF] ceramics with x= 0, 0.05, 0.10, 0.15, and 0.20 using the solid-state combustion method. The phase formation, microstructure, and dielectric, ferroelectric, ferromagnetic, and magnetoelectric properties were investigated. BNBT and NZLAF powders were calcined at 750°C and 900°C for 2 h., respectively. The calcined powders were then mixed in various ratios to produce (1-x)BNBT-xNZLAF composites, which were sintered at 1125°C for 2 h. X-ray diffraction analysis indicated that undoped BNBT ceramics exhibited a typical perovskite structure with coexisting rhombohedral (R) and tetragonal (T) phases. With increasing NZLAF content, the cubic spinel (C) phase emerged with the R and T perovskite phases. Rietveld refinement indicated a higher percentage of the C phase as x increased. When x increased from 0 to 0.10, the average grain size and density increased (from 1.0 to 9.8 m and 5.45 to 5.61 g/cm3, respectively) followed by a drop at higher NZLAF levels. Doping BNBT ceramics with NZLAF resulted in a reduction in the dielectric constant (εr), dielectric loss (tan δ), and remnant polarization (Pr). The undoped BNBT ceramic showed a saturated P-E hysteresis loop, while NZLAF doped ceramics exhibited unsaturated P-E loops and increased leakage current. Magnetic measurements showed a transition from diamagnetic to ferromagnetic behavior with NZLAF doping. As x increased, the remnant magnetization (Mr), saturation magnetization (Ms), and magnetoelectric coefficient also increased (Mr0.058 emu/g, Ms3.594 emu/g, and MEcoefficient 2.64 mV/cm•Oe at x=0.25). These results suggest that NZLAF-doped BNBT ceramics hold potential for multiferroic material applications.
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    Modified energy storage properties of lead-free Sr0.3Bi0.35Na0.335Li0.015TiO3 ceramics with La3+ substitution via the solid-state combustion technique
    (2024-12-01)
    Sinkruason, Thanapon
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    Luangpangai, Anupong
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    Julphunthong, Phongthorn
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    Rittidech, Aurawan
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    Suthapintu, Aekasit
    In this study, the influence of La<sup>3+</sup> substitution on the phase structure, microstructure, electrical and energy storage properties of (Sr<inf>0.3</inf>Bi<inf>0.35</inf>Na<inf>0.335</inf>Li<inf>0.015</inf>)<inf>1-x</inf>La<inf>x</inf>TiO<inf>3</inf> (SBNLT-xLa) ceramics with x = 0–0.05, using the solid-state combustion technique, was investigated. X-ray diffraction (XRD) patterns indicated a pure perovskite structure formed, along with coexisting rhombohedral and tetragonal phases in all ceramics. The Rietveld refinement analysis showed the tetragonal phase increased while the rhombohedral phase decreased with increased La<sup>3+</sup> content. The morphology of the SBNLT-xLa ceramics displayed polygonal grain shapes and anisotropic grain growth. Average grain sizes increased from 2.01 to 2.43 μm as x increased from 0 to 0.01 and afterwards decreased as x increased further. Both the measured density and maximum dielectric constant (ɛ<inf>m</inf>) decreased from 5.48 to 5.29 g/cm<sup>3</sup> and from 4667 to 2313, respectively, when x increased from 0 to 0.05. A decrease in the dielectric properties caused by the phase ratio shifting away from a morphotropic phase boundary (MPB) condition, poor microstructure and low density was produced with La<sup>3+</sup> replacement. The maximum polarization (P<inf>max</inf>), remnant polarization (P<inf>r</inf>) and coercive field (E<inf>c</inf>) decreased with increased La<sup>3+</sup> content. A decline in P<inf>r</inf> and E<inf>c</inf> improved the energy storage efficiency (ƞ) and energy storage loss (W<inf>loss</inf>), resulting in enhanced energy storage properties. At x = 0.02, the ceramic showed good energy storage properties (W<inf>total</inf> of 0.781 J/cm<sup>3</sup>, W<inf>rec</inf> of 0.624 J/cm<sup>3</sup>, W<inf>loss</inf> of 0.157 J/cm<sup>3</sup> and ƞ of 79.8%), measured at 60 kV/cm.
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    Use of the combustion technique for the preparation of Ba(Ti 0.70Zr0.30)O3 ceramics
    (2010-12-01)
    Phungjitt, N.
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    Panya, P.
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    Bongkarn, T.
    The preparation conditions for barium titanate zirconate [Ba(Ti <inf>0.70</inf>Zr<inf>0.30</inf>)O<inf>3</inf>] ceramics by the combustion method were studied. The X-ray diffraction pattern indicated that the calcined powders belonged to a cubic phase. The maximum percentage of the cubic perovskite phase was found in the sample calcined at 850°C. A pure cubic crystal structure was found in all ceramic samples. The average grain size increased with increasing sintering temperatures. The dielectric constant-temperature plots showed a maximum peak value of 5800 from ceramic sintered at 1350°C. The densities of samples corresponded to the dielectric constant. A diffuse phase transition was also observed.