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Effect of quenching technique on electrical properties of KNN ceramics
(2026-05-01)
Sompong, Khanisorn
;
Kaewsit, Sriwan
;
Parjansri, Piewpan
;
Pengpat, Kamonpan
;
Yongsiri, Ploypailin
Cooling rate during sintering constitutes a critical yet systematically underexplored processing variable that governs defect thermodynamics, microstructural evolution, and functional performance in lead-free K<inf>0.5</inf>Na<inf>0.5</inf>NbO<inf>3</inf> (KNN) piezoelectric ceramics. This study establishes quantitative processing-structure-property relationships by systematically comparing two contrasting post-sintering thermal trajectories controlled slow cooling (S-SC) and rapid quenching (S-Q) across sintering temperatures of 1050-1130 °C. Phase-pure KNN ceramics were synthesized via conventional solid-state reaction incorporating 3 mol% excess alkali carbonates and subsequently sintered for 3 h. Structural and microstructural characterization was conducted by X-ray diffraction, scanning electron microscopy, and Archimedes bulk density measurements. Dielectric and ferroelectric responses were evaluated as functions of both sintering temperature and cooling protocol. S-SC processing at 1130 °C yielded synergistic microstructural improvements bulk density of 4.33 g/cm3 (+12.5% relative to 1050 °C), XRD-derived crystallinity of 62% (+24%), and mean grain size of 11.44 μm, that collectively suppressed point-defect concentration through three concurrent mechanisms: elimination of pore-associated extrinsic defect sites, reduction of intrinsic oxygen vacancies (V_O••) via extended thermally activated annihilation, and diminished grain boundary area available for preferential defect segregation. These microstructural advances directly translated into superior dielectric permittivity (εᵣ = 350 at 1 kHz) and remanent polarization (Pᵣ = 0.65 μC/cm2). Conversely, S-Q processing kinetically arrested oxygen vacancy migration and preserved metastable high-temperature domain configurations, yielding competitive permittivity (εᵣ = 242) and enhanced thermal stability at moderate sintering temperatures (1080 - 1100 °C), despite comparatively reduced crystallinity and bulk density. Both thermal protocols preserved the orthorhombic perovskite structure; however, the optimum cooling strategy is demonstrably temperature-dependent. The present findings provide a mechanistic defect-thermodynamic framework and evidence-based thermal processing guidelines for the rational design of high-performance lead-free KNN-family piezoelectric ceramics.
3
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Effect of Ba0.93Ca0.04La0.03Sn0.1Ti0.9O3 addition on structural and electrical properties of lead-free 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 piezoelectric ceramics
(2025-12-01)
Kantha, Puripat
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Unruan, Muangjai
;
Tunkasiri, Tawee
;
Pengpat, Kamonpan
;
Sukkha, Usa
The doping of other materials into the structure of BCZT ceramics can improve the electrical properties. The lead-free piezoelectric ceramics in the (1-x)BCZT–xBCLST binary system, where x = 0.00, 0.01, 0.03, 0.05, and 0.07 mol, were synthesized using a two-step mixed oxide method. Initially, pure phases of 0.5Ba(Zr<inf>0.2</inf>Ti<inf>0.8</inf>)O<inf>3</inf>-0.5(Ba<inf>0.7</inf>Ca<inf>0.3</inf>)TiO<inf>3</inf> (BCZT) and Ba<inf>0.93</inf>Ca<inf>0.04</inf>La<inf>0.03</inf>Sn<inf>0.1</inf>Ti<inf>0.9</inf>O<inf>3</inf> (BCLST) powders were separately prepared by mixed oxide and conventional solid-state reaction methods. X-ray diffraction patterns and Ti K-edge X-ray Absorption Near-Edge Structure (XANES) spectra revealed structural distortions in BCLST-doped ceramics. The electrical properties including dielectric, piezoelectric, and ferroelectric properties were evaluated. Besides, the dielectric constant and dielectric loss at room temperature of BCZT–BCLST ceramics were enhanced with increasing BCLST content. The dielectric properties at room temperature improved with increasing BCLST concentration from x = 0.00 to x = 0.03 mol, with the maximum dielectric constant rising from 1408 to 2552—an increase of approximately 81 %. The hysteresis P–E loop of BCZT–BCLST ceramics exhibited a slim loop, with a maximum remanent polarization (P<inf>r</inf>) of 7.22 μC/cm<sup>2</sup> observed at x = 0.03 mol. The optimal doping condition for BCLST in BCZT ceramics was found at 0.03 mol, yielding the highest piezoelectric coefficient (d<inf>33</inf>) of 235 pC/N—an improvement of approximately 9 % compared to the undoped sample (x = 0.00).
3
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Electrical and magnetic properties of BSFO-NZF multiferroic composite ceramics
(2025-06-01)
Kaewsit, Sriwan
;
Sompong, Khanisorn
;
Pairindra, Worapong
;
Pengpat, Kamonpan
;
Yongsiri, Ploypailin
This study involves the characterization and synthesis of (1-x)Bi<inf>0.9</inf>Sm<inf>0.1</inf>FeO<inf>3</inf> (BSFO) in association with (x)Ni<inf>0.6</inf>Zn<inf>0.4</inf>Fe<inf>2</inf>O<inf>4</inf> (NZF) multiferroic composite ceramics, utilizing x ratios of 0.0, 0.1, 0.3, 0.5, 0.7, and 1.0, achieved through the high-energy planetary ball milling technique and conventional solid-state reaction method. X-ray diffraction confirms the formation of perovskite in the BSFO phase and spinel cubic structure in the NZF phase, absent from any elemental residues. It also signifies the successful incorporation of Sm ions into the BFO lattice. The utilization of field emission scanning electron microscopy (FESEM) combined with energy dispersive X-ray spectroscopy (EDX) for microstructural analysis demonstrates densified structures resulting from reduced grain sizes with the incorporation of NZF and verifies the composition percentages in the BSFO/NZF composite ceramic. The investigation of ferroelectric materials revealed that the ceramic hysteresis loop for the conditions of x = 0.3 and x = 0.5 demonstrated the most optimal ferroelectric behavior. The dielectric constant (ε<inf>r</inf>) exhibited composition-dependent behavior, decreasing from 4895.32 to 44.64 at 1 kHz with increasing NZF content, while demonstrating consistent frequency dispersion across 1 kHz to 1 MHz. Magnetic measurements conducted via vibrating sample magnetometry revealed a substantial increase in saturation magnetization from 0.24 emu/g to 80.06 emu/g as NZF concentration increased, under a maximum applied field of 20 kOe. Enhanced magnetic properties with preserved ferroelectricity enable potential magnetoelectric device applications. This study establishes systematic composition-property relationships that offer insights for optimizing multiferroic composites in practical applications such as sensors, actuators, and data storage devices.
2
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The electrical properties of lanthanide doped potassium sodium lithium niobate based silicate glass
(2021-05-19)
Yongsiri, Ploypailin
;
Sattayapom, Suchinda
;
Senanon, Wipada
;
Pengpat, Kamonpan
In this work, the electrical properties of ferroelectric glass-ceramics in the system of 75((K0.5Na0.5)0.94Li0.06)1-xErxNbO3 - 25SiO2 (75KNLNxEr - 25SiO2) with x varying between 0.005-0.01 mol% have been investigated. The Er2O3 is a lanthanide element that was found to promote the electrical and optical properties in many materials. The data from XRD pattern showed that the prepared glass-ceramics contained crystals of KNLNxEr solid solution, and the crystallite size slightly increased when increasing heat treatment temperature. For dielectric constant and dielectric loss at room temperature, the maximum values of about 304 at 1MHz with a dielectric loss below 0.01 was found in glass-ceramics without Er2O3 dopant. The dielectric value can be raised to 1750 in glass doped with 0.005 mol% of Er2O3 when the measurement temperature is increased. Finally, the oxidation states of glass-ceramics confirm by XANES showed that Er2O3 dopant was Er trivalent cations, and the erbium ions were not precipitated in oxide form.
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