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    Phase Evolution, Microstructure and Electrical Behavior of (Ba0.97Ca0.03)(Ti0.94-x/2Sn0.06-x/2Wx)O3 Ceramics Synthesized via the Solid-State Combustion Technique
    (2022-01-01)
    Udeye, Thanya
    ;
    Onsri, Thanakrit
    ;
    Yotthuan, Surirat
    ;
    Pulphol, Phieraya
    ;
    This research studied the effect of W<sup>4+</sup> substitution on the phase formation, microstructure and electrical properties of (Ba<inf>0.97</inf>Ca<inf>0.03</inf>)(Ti<inf>0.94-x/2</inf>Sn<inf>0.06-x/2</inf>W<inf>x</inf>)O<inf>3</inf> (BCTSW) ceramics with x = 0, 0.005, 0.010, 0.015 and 0.020 mol%. The BCTSW ceramics were synthesized by the solid-state combustion technique, using glycine as fuel. The powders and green pellets of BCTWS were calcined and sintered at 1100 °C for 4 h and 1400 °C for 2 h, respectively. A pure perovskite phase with coexisting orthorhombic and tetragonal phases were observed for all samples. The content of the tetragonal phase increased when x rose, as verified by the Rietveld refinement procedure. The average grain size and the measured density of the samples tended to decrease from 35 ± 0.56 to 1.9 ± 0.12 µm and 5.59 to 4.88 g/cm<sup>3</sup>, respectively, when x increased. The dielectric behavior of the ceramics strongly degenerated upon W<sup>4+</sup> substitution. The undoped BCTS ceramic showed a well-saturated P-E hysteresis loop. With W<sup>4+</sup> substitution, the samples’ P-E loops became unsaturated and a leakage current was created.
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    Phase formation, microstructure and electrical properties of Ba0.9Ca0.1TiO3 ceramics fabricated via the solid-state combustion technique
    (2022-01-01)
    Sonchaopri, Nutkamon
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    Bhupaijit, Pamornnarumol
    ;
    Yotthuan, Surirat
    ;
    Sinkruason, Thanapon
    ;
    Premwichit, Pathit
    In this research, the effects of calcination temperature in a range of 1050–1200 °C for 2 h and sintering temperature in a range of 1325-1400 °C for 2 h on phase formation, microstructure and electrical properties of lead-free Ba<inf>0.9</inf>Ca<inf>0.1</inf>TiO<inf>3</inf> (BCT) ceramics fabricated via the solid-state combustion technique were investigated. For the XRD result, all the ceramics exhibited a coexisting phase between tetragonal and orthorhombic. The ceramic grain size tended to increase with increase of the sintering temperature. For BCT ceramic produced by the optimum sintering temperature (1375 °C for 2 h), the dielectric, ferroelectric and piezoelectric properties of ε <inf>C</inf>=7393, P <inf>r</inf>=7.60 μC/cm<sup>2</sup><inf>,</inf> E <inf>C</inf>=5.99 kV/cm and d <inf>33</inf>=158 pC/N, respectively, were obtained.
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    Effect of the Firing Temperatures on the Phase Evolution and Electrical Properties of 0.85[0.94Bi0.5Na0.5TiO3-0.06BaTiO3]-0.15[Na0.73Bi0.09NbO3] Ceramics Synthesized via the Solid-State Combustion Method
    (2023-01-01)
    Pattanakasem, Wiwat
    ;
    Yotthuan, Surirat
    ;
    Hongsamsibjed, Pakornkiat
    ;
    Suriwong, Tawat
    ;
    Prasertpalichat, Sasipohn
    In this research paper, we describe 0.85[0.94Bi<inf>0.5</inf>Na<inf>0.5</inf>TiO<inf>3</inf>-0.06BaTiO<inf>3</inf>]-0.15[Na<inf>0.73</inf>Bi<inf>0.09</inf>NbO<inf>3</inf>] (BNT-BT-NBN) ceramics fabricated by the solid-state combustion technique. The phase evolution, microstructure, dielectric, ferroelectric and energy storage properties were examined. The BNT-BT-NBN powders and ceramics were calcined and sintered between 650–900 °C and 1100–1175 °C, respectively, for 2 h. All samples showed a typical perovskite structure, as revealed by X-ray diffraction. The Rietveld refinement analysis of the ceramics suggested the samples sintered between 1100 and 1150 °C had coexisting R + T phases, while the R + T+C phases were observed in the ceramics sintered at 1175 °C. The average grain size of the samples increased from 0.52 to 1.39 μm with increased sintering temperature. The density of the ceramics increased from 5.12 to 5.45 g/cm<sup>3</sup> when the sintering temperature increased from 1100 to 1150 °C, and then decreased. Increasing the sintering temperature from 1100 to 1150 °C caused the dielectric constant at T <inf>s</inf> (ε <inf>s</inf>) and the dielectric constant at T <inf>m</inf> (ε <inf>m</inf>) to increase from 1727 to 1945 and 1564 to 1750, respectively, and then ε <inf>s</inf> and ε <inf>m</inf> declined. All BNT-BT-NBN ceramics had good dielectric temperature stability with only a±10% change when the temperature ranged from room temperature to ∼300 °C. The optimum energy-storage properties (W <inf>rec</inf> = 0.62 J/cm<sup>3</sup> and η = 83.2%) were obtained from the BNT-BT-NBN ceramics sintered at 1150 °C for 2 h. This data indicates that BNT-BT-NBN ceramics can be useful as lead-free materials for high density energy-storage capacitors.
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    Phase evolution, microstructure and electrical response of KNNT ceramics with Li+ substitution and doping
    (2022-01-01)
    Yotthuan, Surirat
    ;
    Udeye, Thanya
    ;
    Prasertpalichat, Sasiphon
    ;
    Pulphol, Phieraya
    ;
    Lead-free (K<inf>0.5</inf>Na<inf>0.5</inf>)(Nb<inf>0.7</inf>Ta<inf>0.3</inf>)O<inf>3</inf> (KNNT) ceramics with Li<sup>+</sup> substitution (KN<inf>0.5-x</inf>Li<inf>x</inf>NT) and direct (KNNT-xLi) doping at x = 0, 0.01, 0.02, 0.03 and 0.04 mol% were synthesized by the solid-state combustion route. The phase, microstructure, dielectric and ferroelectric properties of the ceramics were examined. The XRD pattern of the ceramics revealed orthorhombic and tetragonal phases in all specimens. The Rietveld refinement procedure showed that increasing either the Li<sup>+</sup> substitution or doping levels enhanced the amount of the tetragonal phase. It was found that Li<sup>+</sup> doping, either substitutional or additional, enhanced the Curie temperature (T <inf>C</inf>) by increasing the tetragonal distortion, while the dielectric constant (ε <inf>C</inf>) decreased. The good remanent P-E loops of the KN<inf>0.5-x</inf>Li<inf>x</inf>NT ceramics were found with x = 0.01 (P <inf>r</inf>∼10.89 µC/cm<sup>2</sup> and E <inf>C</inf>∼13.09 kV/cm), while for KNNT-xLi ceramics, it was obtained with x = 0.02 (P <inf>r</inf>∼15.65 µC/cm<sup>2</sup> and E <inf>C</inf>∼11.46 kV/cm), which were confirmed by remanent P-E hysteresis measurements.
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    Effect of Firing Conditions on Phase Formation, Microstructure, and Electrical Properties of (K0.5Na0.5)(Nb0.7Ta0.3)O3 Ceramics Synthesized by Solid-State Combustion Method
    (2020-10-01)
    Yotthuan, Surirat
    ;
    Charoonsuk, Thitirat
    ;
    ;
    Thountom, Sarawut
    ;
    Suriwong, Tawat
    The effect of the firing conditions on the phase formation, microstructure, and electrical properties of (K<inf>0.5</inf>Na<inf>0.5</inf>)(Nb<inf>0.7</inf>Ta<inf>0.3</inf>)O<inf>3</inf> (KNNT) ceramics synthesized by the solid-state combustion technique using glycine as fuel has been investigated. All samples were calcined at 600°C to 800°C for 2 h and sintered at 1150°C to 1190°C for 2 h to 5 h. Pure KNNT powders were produced after calcination at 600°C for 2 h. The average particle size increased when the calcination temperature was increased. The KNNT powder calcined at 600°C for 2 h showed rather square morphology with average particle size of ∼ 160 nm. The x-ray diffraction (XRD) analysis results for the ceramics revealed the presence of orthorhombic (O) and tetragonal (T) phases in all samples. When sintering at 1150°C for 4 h, the O:T ratio was 50:50, as verified by the Rietveld refinement technique. The average grain size, density values, and dielectric properties tended to increase when the dwell time was increased from 2 h to 4 h, but then degraded. The KNNT ceramic produced at the optimum firing condition (1150°C for 4 h) showed good crystalline morphology, the highest density (ρ = 5.28 g/cm<sup>3</sup>), the highest dielectric constant (ε<inf>C</inf> = 5002), and good ferroelectric behavior (P<inf>r</inf> = 18.50 μC/cm<sup>2</sup> and E<inf>c</inf> = 9.04 kV/cm).
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    Effect of Co2+ substitution in B-sites of the perovskite system on the phase formation, microstructure, electrical and magnetic properties of Bi0.5(Na0.68K0.22Li0.10)0.5TiO3 ceramics
    (2022-09-01)
    Bhupaijit, Pamornnarumol
    ;
    Kaewsai, Chonnarong
    ;
    Suriwong, Tawat
    ;
    Pinitsoontorn, Supree
    ;
    Yotthuan, Surirat
    Bi<inf>0.5</inf>(Na<inf>0.68</inf>K<inf>0.22</inf>Li<inf>0.10</inf>)<inf>0.5</inf>Ti<inf>1−x</inf>Co<inf>x</inf>O<inf>3</inf> lead-free perovskite ceramics (BNKLT−xCo, x = 0, 0.005, 0.010, 0.015 and 0.020) were fabricated via the solid-state combustion technique. A small-amount of Co<sup>2+</sup> ion substitution into Ti-sites led to modification of the phase formation, microstructure, electrical and magnetic properties of BNKLT ceramics. Coexisting rhombohedral and tetragonal phases were observed in all samples using the X-ray diffraction (XRD) technique. The Rietveld refinement revealed that the rhombohedral phase increased from 39% to 88% when x increased from 0 to 0.020. The average grain size increased when x increased. With increasing x, more oxygen vacancies were generated, leading to asymmetry in the bipolar strain (S−E) hysteresis loops. For the composition of x = 0.010, a high dielectric constant (ε<inf>m</inf>) of 5384 and a large strain (S<inf>max</inf>) of 0.23% with the normalized strain (d*<inf>33</inf>) of 460 pm·V<sup>−1</sup> were achieved. The BNKLT−0Co ceramic showed diamagnetic behavior but all of the BNKLT−xCo ceramics exhibited paramagnetic behavior, measured at 50 K.
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    INFLUENCE OF Pr6O11-DOPING ON THE CRYSTAL STRUCTURE AND ELECTRICAL PROPERTIES OF BNBT PIEZOELECTRIC CERAMICS
    (2025-01-01)
    Yotthuan, Surirat
    ;
    Sawangboon, Nuttawan
    ;
    Meechoowas, Ekarat
    ;
    Bongkarn, Theerachai
    ;
    In this work, a series of lead-free 0.97(Bi<inf>0.5</inf>Na<inf>0.5</inf>)TiO<inf>3-</inf>0.03BaTiO<inf>3-x</inf>Pr<inf>6</inf>O<inf>11</inf> (BNBT-xPr) piezoelectric materials with x=0, 0.1, 0.3, 0.5, and 0.7 wt.% were created by the solid-state combustion route, to enhance their electric properties. The investigation on the phase evolution, microstructure, and electrical behavior of the specimens were carried out. The powders and ceramics were calcined and sintered for two hours at 800℃ and 1180℃, correspondingly. All examples displayed a perfect perovskite lattice and no detectable impurity phase. XRD pattern examination for the ceramics disclosed the existence of rhombohedral and tetragonal phases in all examples. The rhombohedral phase was boosted by rising the doping levels, as established by the Rietveld refinement study. As the x content rose, the average grain size and measured density began to decrease from 0.90±0.10 to 0.73±0.07 μm and 6.13 to 6.05 g/cm<sup>3</sup>, correspondingly. It was noticed that Pr<inf>6</inf>O<inf>11</inf> doping, decreased dielectric properties. The remnant polarization (Pr) of the samples rises from 22.2 to 27.7 μC/cm<sup>2</sup> with x rises from 0 to 0.3 and then dropped. The coercive field (Ec) of the ceramics rises significantly when Pr<inf>6</inf>O<inf>11</inf> was incorporated. The BNBT lead-free ceramics doped with 0.3wt%Pr<inf>6</inf>O<inf>11</inf>, with a high Pr value, could be a promising candidate for memory applications to replace Pb-based ceramics.
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    The influences of Cs+ substitution and direct doping on the phase evolution, microstructure and electrical properties of KNNT ceramics
    (2021-01-01)
    Yotthuan, Surirat
    ;
    Udeye, Thanya
    ;
    ;
    Eitssayeam, Sukum
    ;
    Pulphol, Phieraya
    The effects of Cs<sup>+</sup> substitution and direct doping in (K<inf>0.5</inf>Na<inf>0.5</inf>)(Nb<inf>0.7</inf>Ta<inf>0.3</inf>)O<inf>3</inf> (KNNT) ceramics, on the crystal structure, microstructure and electrical properties were investigated. Both the KNNT with Cs<sup>+</sup> substitution (K<inf>0.5-x</inf>Cs<inf>x</inf>NNT) and addition (KNNT-xCs) (x = 0, 0.01, 0.02, 0.03 and 0.04 mol%) were synthesized by the solid-state combustion technique using glycine as fuel. All samples were sintered at 1130–1150 °C for 4 h. The x-ray diffraction (XRD) analysis for the ceramics revealed the presence of orthorhombic (O) and tetragonal (T) phases in all samples. Increasing both the Cs<sup>+</sup> substitution and doping amounts, enhanced the content of orthorhombic phase, as verified by the Rietveld refinement technique. It was found that Cs<sup>+</sup> doping, either substitutional or additional, strongly decreased their density, dielectric and ferroelectric properties. The undoped KNNT ceramic exhibited well-saturated P-E hysteresis loop. With Cs<sup>+</sup> doping, the samples became unsaturated and a leakage current was produced. The KNNT-xCs ceramics demonstrated higher density and dielectric properties than the K<inf>0.5-x</inf>Cs<inf>x</inf>NNT ceramics.
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    Structure–property correlations and magnetoelectric response of lead-free BNT–BCTS/CZFMO composite ceramics
    (2026-06-01)
    Kornphom, Chittakorn
    ;
    Sonchaopri, Nutkamon
    ;
    Yimsabai, Sununta
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    Yotthuan, Surirat
    ;
    Jantaratana, Pongsakorn
    Lead-free multiferroic composite ceramics have garnered increasing attention as an eco-friendly alternative for magnetoelectric (ME) devices. In this work, (100-x) [0.93(Bi<inf>0.5</inf>Na<inf>0.5</inf>TiO<inf>3</inf>) 0.07(Ba<inf>0.945</inf>Ca<inf>0.055</inf>Ti<inf>0.91</inf>Sn<inf>0.09</inf>O<inf>3</inf>)]/xCo<inf>0.6</inf>Zn<inf>0.4</inf>Fe<inf>1.7</inf>Mn<inf>0.3</inf>O<inf>4</inf> composite ceramics, abbreviated as (100-x) BNT-BCTS/xCZFMO were synthesized via a solid-state combustion route. Analysis of XRD data using the Rietveld method confirmed the coexistence of rhombohedral and tetragonal perovskite (BNT–BCTS) phases and a cubic spinel (CZFMO) phase without additional impurity phases. The 0–3 connectivity was verified using SEM/EDS, PFM, and MFM measurements, confirming discrete CZFMO magnetic grains are embedded within a continuous BNT–BCTS piezoelectric matrix. Williamson–Hall (W–H) analysis, treated as a semi-quantitative approach due to fitting limitations in the multiphase composite system, suggested a composition-dependent microstrain trend. The reduced microstrain at intermediate CZFMO contents was consistent with enhanced crystallite growth, improved densification, and the maximum magnetoelectric response. The composition with x = 20 exhibits the highest relative density (~ 98.14%), the highest saturation magnetization (M<inf>s</inf> = 6.55 emu/g), and the maximum magnetoelectric coefficient (α<inf>ME</inf> = 7.92 mV cm<sup>−1</sup> Oe<sup>−1</sup>), showing higher ME coefficients than many previously reported lead-free composites. This work demonstrates the potential of BNT–BCTS/CZFMO composites for multifunctional electronic devices, including magnetic sensors, energy harvesters, and magnetoelectric transducers.