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Enhanced densification and thermoelectric properties of Ca3Co4O9 ceramics fabricated by solid-state combustion and hot-pressing
(2026-11-15)
Thatawong, Bhoowadol
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Sriondee, Manlika
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Chongsatan, Wistsarut
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Palaporn, Dulyawich
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Pinitsoontorn, Supree
The Ca<inf>3</inf>Co<inf>4</inf>O<inf>9</inf> powders were synthesized by the solid-state combustion method and then calcined at 775-875 °C for 6 h. The combination of combustion-derived fine powders and hot pressing was adopted to improve the densification and thermoelectric (TE) performance of Ca<inf>3</inf>Co<inf>4</inf>O<inf>9</inf> ceramics. Dense Ca<inf>3</inf>Co<inf>4</inf>O<inf>9</inf> ceramics were subsequently fabricated by hot-pressing to investigate the influence of hot-pressing temperature (800-950 °C, 2 h) on phase formation, microstructure, electrical, and TE properties. The Ca<inf>3</inf>Co<inf>4</inf>O<inf>9</inf> powder was obtained after calcination at 800 °C for 6 h and exhibited an average particle size of 0.55 μm. XRD analysis confirmed that Ca<inf>3</inf>Co<inf>4</inf>O<inf>9</inf> was the predominant phase in all hot-pressed samples. XPS analysis further confirmed the presence of oxygen vacancy (V<inf>O</inf>++)-related defects and mixed-valence cobalt species. FESEM observations revealed a dense microstructure composed of plate-like grains with an average grain size ranging from 0.61 to 0.96 μm. The bulk density ranged from 4.31 to 4.46 g/cm3, indicating dense ceramics. The electrical resistivity (ρ) decreased with increasing measured temperature for all samples. Among all samples, the ceramic hot-pressed at 900 °C exhibited the lowest ρ at 600 °C. The Seebeck coefficient (S) significantly increased from 150 μV/K to 223 μV/K, while the thermal conductivity (κ) decreased with increasing temperature. Due to the favorable combination of low ρ and high S, the sample hot-pressed at 900 °C achieved the highest power factor (PF) and a maximum dimensionless figure of merit (ZT) of 0.17 at 600 °C.
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Structure–property correlations and magnetoelectric response of lead-free BNT–BCTS/CZFMO composite ceramics
(2026-06-01)
Kornphom, Chittakorn
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Sonchaopri, Nutkamon
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Yimsabai, Sununta
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Yotthuan, Surirat
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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−1 Oe−1), 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.
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Optimal Bi₀.₈Ba₀.₂FeO₃ doping in Bi₀.₅(Na₀.₇₇K₀.₂₀Li₀.₀₃)₀.₅TiO₃ multiferroic ceramics synthesized by the solid-state combustion technique
(2025-12-01)
Thawong, Pichittra
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Prasertpalichat, Sasipohn
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Suriwong, Tawat
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Pinitsoontorn, Supree
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Jantaratana, Pongsakorn
(1-x)Bi<inf>0.5</inf>(Na<inf>0.77</inf>K<inf>0.20</inf>Li<inf>0.03</inf>)<inf>0.5</inf>TiO<inf>3</inf>-xBi<inf>0.8</inf>Ba<inf>0.2</inf>FeO<inf>3</inf> ((1-x)BNKLT-xBBF) ceramics with x = 0-0.4 were synthesized by the solid-state combustion technique. X-ray diffraction (XRD) analysis confirmed a pure perovskite structure with coexisting rhombohedral and tetragonal phases. Rietveld refinement revealed that the unit cell volume increased with increased x due to the substitution of smaller Bi3+ and Ti4+ ions by larger Ba2+ and Fe3+ ions at the A- and B-sites, respectively. The average grain size and measured density also increased with increasing x, while the resistivity decreased. At room temperature, (1-x)BNKLT-xBBF ceramics with x = 0.2–0.4 exhibited multiferroic behavior, characterized by ferroelectric and ferromagnetic hysteresis loops. The 0.8BNKLT-0.2BBF ceramic exhibited the most favorable properties, including: the highest relative density (95.48%), the highest dielectric constant and low dielectric loss at room temperature (ε<inf>R</inf> = 1746 and tan δ<inf>R</inf> = 0.0296), good ferroelectric properties (P<inf>r</inf>=6.46 µC/cm2 and E<inf>c</inf>=11.84 kV/cm) and good ferromagnetic properties (M<inf>r</inf>=0.002 emu/g, H<inf>c</inf>=110 Oe and α<inf>E</inf> = 1.092 mV/Oe·cm). These results indicate that 0.8BNKLT-0.2BBF has the potential for applications in lead-free, room temperature multiferroic applications.
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Multifunctional properties of Mn and Fe co-doped lead-free BCT perovskite ceramics synthesized via solid-state combustion
(2025-10-01)
Kornphom, Chittakorn
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Sonchaopri, Nutkamon
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Yimsabai, Sununta
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Jantaratana, Pongsakorn
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Pinitsoontorn, Supree
There is a growing demand to improve the performance of multiferroic lead-free ceramics. Good ferroelectric and magnetic properties are key parameters for achieving high magnetoelectric coupling (ME). In this work, Mn and Fe were co-doped into lead-free Ba<inf>0.96</inf>Ca<inf>0.04</inf>Ti<inf>(1-x)</inf>(Mn<inf>0.5</inf>Fe<inf>0.5</inf>)<inf>x</inf>O<inf>3</inf> (BCT-xMF) ceramics with 0 ≤ x ≤ 0.030 mol%, synthesized by the solid-state combustion technique. X-ray diffraction (XRD) analysis and Rietveld refinement confirmed the formation of a pure phase with coexisting tetragonal and cubic phases in all compositions. As the Mn/Fe content increased, the percentage of the tetragonal phase decreased while the cubic phase increased, consistent with Raman spectroscopy results. Increasing Mn/Fe content also led to more oxygen vacancies and defects, and a decrease in average grain size. Analysis of the temperature-dependent dielectric constant revealed a reduction in the Curie temperature from 116 to 67 °C, corresponding to the tetragonal-to-cubic phase transformation. The ceramic with x = 0.015 showed the highest dielectric constant at the Curie temperature (ε<inf>c</inf>), maximum saturated polarization (P<inf>s</inf>), remnant polarization (P<inf>r</inf>), saturation magnetization (M<inf>s</inf>), and remnant magnetization (M<inf>r</inf>), with values of 4583, 14.09 μC/cm2, 9.31 μC/cm2, 0.0127 emu/g, and 0.006 emu/g, respectively. These results indicate that Fe/Mn co-doping into BCT ceramics enhanced both ferroelectric and ferromagnetic properties, resulting in a high magnetoelectric coefficient (α<inf>ME</inf>∼1.27 mV/cm Oe) at room temperature, making these ceramics candidates for multiferroic applications.
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Electric and magnetic properties of multiferroic CZFMO doped BNLTBKTBaT composite ceramics prepared via the solid-state combustion method
(2025-07-01)
Klinbanmor, Metarsit
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Thatawong, Bhoowadol
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Somsri, Widchaya
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Prasertpalichat, Sasiphon
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Vittayakorn, Naratip
The present research work describes in detail investigations of the multiferroic properties of (1-x) (0.85Bi<inf>0.5</inf>Na<inf>0.475</inf>Li<inf>0.025</inf>TiO<inf>3</inf>-0.11Bi<inf>0.5</inf>K<inf>0.5</inf>TiO<inf>3</inf>-0.04BaTiO<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> [(1-x)BNLTBKTBaT-xCZFMO]; x = 0, 0.05, 0.10, 0.15 and 0.20 composite ceramics, synthesized by the solid-state combustion technique. The effect of increasing x content on the phase structure, microstructure, electrical and magnetic properties of (1-x)BNLTBKTBaT-xCZFMO composite ceramics was investigated. X-ray diffraction patterns of the BNLTBKTBaT sample showed a pure perovskite phase (rhombohedral and tetragonal structures). When CZFMO was added, the XRD patterns showed a co-structure between perovskite and cubic spinel ferrite structures. The composite grains were composed of large and small sizes, which were composed of mainly the elements of BNLTBKTBaT and CZFMO, respectively. As x increased, the average grain size of the larger grains increased, and the smaller grains got smaller. The density decreased from 5.54 to 4.61 g/cm3 as x increased. Increasing the amount of CZFMO in BNLTBKTBaT also resulted in a decrease in the dielectric constant (ε<inf>r</inf>) and the remnant polarization (P<inf>r</inf>), with the leakage current observed at x = 0.20. The saturation magnetization (M<inf>s</inf>) and the magnetoelectric coupling coefficient (α<inf>E</inf>) increased with increased x. It was found that x = 0.15 gave the optimal electric, magnetic, and magnetoelectric properties (ε<inf>r</inf> = 425, P<inf>r</inf> = 1.64 μC/cm, M<inf>s</inf> = 1.1948 emu/g and α<inf>E</inf> = 4.88 mV/cm-Oe), which makes the composite potentially more applicable for information technology and spintronics devices.
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Improved Dielectric, Magnetic, and Multiferroic Properties of (Bi0.5Na0.5)0.7La0.3(Ti0.7Fe0.3)O3 Ceramics Synthesis by the Solid-State Combustion Technique
(2025-06-01)
Kornphom, Chittakorn
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Somsri, Widchaya
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Prasertpalichat, Sasipohn
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Thatawong, Bhoowadol
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Kruea-In, Chatchai
Lead-free (Bi<inf>0.5</inf>Na<inf>0.5</inf>)<inf>0.7</inf>La<inf>0.3</inf>(Ti<inf>0.7</inf>Fe<inf>0.3</inf>)O<inf>3</inf> ceramics (abbreviated as BNLTF) are synthesized by the solid-state combustion technique using glycine as fuel. The effect of the firing temperature (calcined between 700 and 800 °C for 2 h and sintered between at 800 and 900 °C for 2 h) on the phase structure, microstructure, electrical, and magnetic properties is investigated. Pure BNLTF powders are obtained with a calcination temperature of 750 °C for 2 h and the crystal size increases from 47 to 62 nm when the calcination temperature increases from 700 to 800 °C. All sintered BNLTF ceramics show a pure perovskite structure with a rhombohedral phase. The average grain size increases with increasing sintering temperatures. A well-packed microstructure with the highest density (5.98 g cm−3), good dielectric properties at room temperature (ε<inf>r</inf> ≈ 589 and tanδ ≈ 0.572), soft ferroelectric behavior, and excellent magnetic properties (M<inf>s</inf> ≈ 0.091 emu g−1, M<inf>r</inf> ≈ 0.0026 emu g−1) is obtained from the ceramic sintered at 875 °C for 2 h. The multiferroic BNLTF ceramic sintered at 875 °C has a maximum magnetoelectric coupling coefficient (α<inf>E</inf> ≈ 2.08 mV cm−1 Oe−1) when the magnetic field is near 4500 Oe.
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Design and Implementation of a High-Field NdFeB Magnet System for Investigating the Spin Seebeck Effect
(2025-01-01)
Nachaithong, Theeranuch
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Wongjom, Chalothon
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Samransuksamer, Benjarong
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Phumying, Santi
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Pongophas, Ekkarat
The generation of pure spin current through thermal gradients, known as the spin Seebeck effect (SSE), has garnered significant interest in spintronics. In this study, we design and construct a permanent magnetic instrument setup to generate a variable external magnetic field using NdFeB permanent magnets to observe the SSE. The experimental setup is composed of three crucial components: the magnetic field, the temperature gradient, and electronic control systems. Si/yttrium iron garnet (YIG)/platinum (Pt) and Si/nickel (Ni) samples, prepared via sputtering techniques, were utilized for standard calibration purposes. The results show that the external magnetic field produced by NdFeB varies with the gap distance between the two magnetic poles, following an exponential decrease in field strength with increasing gap distance. The magnetic field at the center can be adjusted from ±20 to ±5000 Oe. The temperature gradient stabilizes after approximately 10 min, with a temperature difference ( ΔT ) between the heated and cooled sides ranging from 0 to 30 K. For instrument testing, we performed magnetic field and angle-dependent measurements on Si/YIG/Pt and Si/Ni samples. The results indicate that the magnetic field dependence of the permanent magnet instrument (PMI) does not exhibit the voltage loop switching seen with an alternative magnetic coil (AMC) but shows analogous behavior at high magnetic fields. Moreover, the angle dependence of both PMI and AMC yielded comparable results. In conclusion, our PMI setup procedures effectively facilitate the observation of the SSE.
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INFLUENCE OF SINTERING TEMPERATURES ON MULTIFERROIC PROPERTIES OF LEAD-FREE BNT-BT-NZF MULTIFERROIC COMPOSITE FABRICATED VIA THE SOLID-STATE COMBUSTION TECHNIQUE
(2025-01-01)
Chongsatan, Wistsarut
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Boonpluk, Wiranchana
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Vittayakorn, Naratip
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Pinitsoontorn, Supree
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Jantaratana, Pongsakorn
There has been a growing interest in multiferroics, materials that combine magnetic and electric ordering, over the past few years. This research investigates the influence of sintering temperature (1075-1175°C for 2 hours) on multiferroic properties of 0.7(0.94Bi<inf>0.5</inf>Na<inf>0.5</inf>TiO<inf>3</inf>-0.06BaTiO<inf>3</inf>)-0.3(Ni<inf>0.7</inf>Zn<inf>0.3</inf>Fe<inf>2</inf>O<inf>4</inf>) (BNT-BT-NZF) multiferroic composites, fabricated using solid-state combustion with glycine as a fuel was investigated. The XRD patterns of all ceramics revealed the coexistence of a rhombohedral ferroelectric phase, a tetragonal ferroelectric phase, and a cubic ferromagnetic phase. The average grain size, dielectric constant (ε<inf>r</inf>), dielectric loss (tanδ), remnant polarization (P<inf>r</inf>), and coercive field (E<inf>c</inf>) tended to increase from 0.66 to 2.5μm, 314 to 829, 0.22 to 0.51, 0.36 to 5.82 μC/cm2, and 7.05 to 26.96 kV/cm, respectively, with increase of sintering temperature. The composite ceramics exhibited peak saturation magnetization (M<inf>s</inf> ~ 12.21 emu/g) and magnetoelectric (ME) coupling (~ 3.59 mV/cmOe) when sintered at 1150°C.
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ELECTRIC AND MAGNETIC PROPERTIES OF Ba0.97Ca0.03Ti0.94Sn0.06O3-Mn0.85Ni0.15Zn0.15Fe2O4 MULTIFERROIC CERAMIC COMPOSITES FABRICATED VIA THE SOLID-STATE COMBUSTION TECHNIQUE
(2025-01-01)
Sonchaopria, Nutkamon
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Meechob, Jirayut
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Thatawong, Bhoowadol
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Vittayakorn, Naratip
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Pinitsoontorn, Supree
Multiferroic composites with the general formula (1-x)(Ba0.97Ca0.03Ti0.94Sn0.06O3)-x(Mn0.85Ni0.15Zn0.15Fe2O4) (BCTS/MNZF) (x = 0.1, 0.2, 0.3, 0.4, and 0.5) were prepared using the solid-state combustion method. The structure, morphology, dielectric, ferroelectric, magnetic, and magnetoelectric properties were analyzed. The samples were sintered at 1,300ºC for 2 h. The X-ray Diffraction (XRD) patterns revealed tetragonal perovskite, orthorhombic perovskite, and cubic spinel structures corresponding to the BCTS and MNZF phases. Secondary phases (Mn2O3 and SnO) appeared in the sintered samples with x>0.2. Increasing MNZF content enhanced ferrite grain growth in the composites. The dielectric constant showed an overall decreasing trend with increasing MNZF content, with a smaller effect at lower frequencies. At lower frequencies, the dielectric constant declined with increasing frequency before stabilizing around 10 kHz. As ferrite content increased, the density, dielectric constant, and magnetoelectric coefficient (αME) decreased from 5.66 to 5.12 g/cm³, 1388 to 862, and 7.24 to 4.05 mV/cm·Oe, respectively. While the saturation magnetization (Ms) rose substantially from 0.75 to 13.14 emu/g. These findings offer valuable insights into enhancing lead-free multiferroic composite ceramics for targeted applications in magnetoelectric devices.
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ELECTRICAL AND MAGNETIC PROPERTIES OF MULTIFERROIC Co0.6Zn0.4Fe1.7Mn0.3O4 DOPED 0.99Bi0.47Na0.47Ba0.06TiO3-0.01Ba(Sn0.70Nb0.24)O3 CERAMICS SYNTHESIZED VIA THE SOLID-STATE COMBUSTION TECHNIQUE
(2025-01-01)
Luangpangai, Anupong
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Chuai, Phomphon
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Rittidech, Aurawan
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Pinitsoontorn, Supree
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Jantaratana, Pongsakorn
Multiferroic (1-x)[0.99Bi<inf>0.47</inf>Na<inf>0.47</inf>Ba<inf>0.06</inf>TiO<inf>3</inf>-<inf>0.01</inf>Ba(Sn<inf>0.70</inf>Nb<inf>0.24</inf>)O<inf>3</inf>]-xCo<inf>0.6Z</inf>n<inf>0.4</inf>Fe<inf>1.7</inf>Mn<inf>0.3</inf>O<inf>4</inf> (abbreviated as BNBT-BSN-xCZFMO) ceramics with x ranging from 0 to 0.20 were fabricated using the solid-state combustion technique. The effect of varying BNBT-BSN: CZFMO ratios on the phase structure, microstructure, electrical and magnetic properties was investigated. X-ray diffraction (XRD) analysis of pure BNBT-BSN showed a perovskite structure with rhombohedral and tetragonal phases. The doped BNBT-BSN-xCZFMO ceramics displayed coexisting rhombohedral, tetragonal, and cubic spinel phases, with the cubic spinel phase increasing when the CZFMO content increased. In addition, the XRD peaks shifted to higher angles as the CZFMO content increased, indicating a decrease in lattice parameters. The dielectric constant decreased with higher CZFMO content and higher frequencies. The pure BNBT-BSN ceramic exhibited a saturated P-E loop with a Pmax of 33.2 µC/cm2, Pr of 26.1 µC/cm2, and an Ec of 14.5 kV/cm. With increased CZFMO content, non-saturated and bloated P-E loops with lower Pmax, Pr, and Ec were observed, implying a rise in the leakage current. The addition of CZFMO induced ferromagnetic behavior in the ceramics, leading to an increase in Ms and a reduction in Hc as CZFMO content increased. The magnetoelectric coupling coefficient of BNBT-BSN-xCZFMO ceramics continuously increased with higher CZFMO content.

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