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Effect of quenching technique on electrical properties of KNN ceramics
(2026-05-01)
Sompong, Khanisorn
;
Kaewsit, Sriwan
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Parjansri, Piewpan
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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.
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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.
1
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Investigation on ferromagnetic and ferroelectric properties of (La, K)-doped BiFeO3-BaTiO3 solid solution
(2013-05-01)
Prasatkhetragarn, Anurak
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Muangkonkad, Pantip
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Aommongkol, Parichart
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Jantaratana, Pongsakorn
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Vittayakorn, Naratip
Multiferroic materials of BiFeO<inf>3</inf>-BaTiO<inf>3</inf> solid solution have been fabricated in order to improve ferromagnetic and ferroelectric properties. The effects of La (1 mol%) and K (varied from 0.5-5 mol%) doped 0.75BiFeO<inf>3</inf>-0.25BaTiO<inf>3</inf> on phase formation, ferromagnetic and ferroelectric properties have been investigated and discussed. The rhombohedral perovskite phase of specimens was characterized by XRD technique. Fracture morphology reveals the grain growth characteristics with increasing K content. (La, K)-doped 0.75BiFeO<inf>3</inf>-0.25BaTiO<inf>3</inf> with La=1 mol% and K=3 mol% exhibits the highest remnant polarization and remnant magnetization. © 2012 Elsevier Ltd and Techna Group S.r.l.
1
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Synthesis and dielectric and ferroelectric properties of ceramics in (1 - X)Pb(Zr1/2Ti1/2)O3-(x)Pb(Co 1/3Nb2/3)O3 system
(2008-02-15)
Prasatkhetragarn, Anurak
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Vittayakorn, Naratip
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Ananta, Supon
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Yimnirun, Rattikorn
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Cann, David P.
Ceramics in a PZT-PCN system with the formula (1 - x)Pb(Zr <inf>1/2</inf>Ti<inf>1/2</inf>)O<inf>3</inf>-(x)Pb(Co<inf>1/3</inf>Nb <inf>2/3</inf>)O<inf>3</inf>, where x = 0.1-0.5, were prepared using a solid-state mixed-oxide technique (the columbite-wolframite precursor method). The phase formation behavior and microstructure were studied using X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM), respectively. The dielectric and ferroelectric properties of the compounds were studied and discussed. Phase-pure perovskites of PZT-PCN ceramics were obtained over a wide compositional range. In addition, the XRD, dielectric, and ferroelectric properties confirmed that the morphotropic phase boundary (MPB) composition between the tetragonal and pseudo cubic phases of this system lied between 0.2 ≤ × ≤ 0.3. © 2008 The Japan Society of Applied Physics.
3
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Influence of fabrication processing on phase transition and electrical properties of 0.8Pb(Zr1/2Ti1/2)O3-0.2Pb(Ni 1/3Nb2/3)O3 ceramics
(2008-01-01)
Rujijanagul, G.
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Vittayakorn, N.
The binary system of 0.8Pb(Zr<inf>1/2</inf>Ti<inf>1/2</inf>)O<inf>3</inf>-0.2Pb(Ni <inf>1/3</inf>Nb<inf>2/3</inf>)O<inf>3</inf> ceramics were synthesized by conventional mixed oxide and columbite method. X-ray diffraction analysis demonstrated the coexistence of both the rhombohedral and tetragonal phases for the columbite prepared sample. Rhombohedral to tetragonal phase transition for columbite method was different compared with those of the mixed oxide method. The permittivity shows a shoulder at the rhombohedral to tetragonal phase transition temperature T<inf>Rho-Tetra</inf> = 195 °C, and then a maximum permittivity (36,000 at 10 kHz) at the transition temperature T<inf>m</inf> = 277 °C on ceramics prepared with the columbite method. However, piezoelectric coefficient (d<inf>33</inf>) was measured to be 282 pC/N for the conventional method and higher than the columbite method. The results were related to the phase compositions and porosity of the ceramics. © 2007 Elsevier B.V. All rights reserved.
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Influence of strontium doping on the ferroelectric and piezoelectric properties of lead zinc niobate-lead zirconate titanate ceramics
(2007-12-01)
Vittayakorn, Naratip
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Bongkarn, Theerachai
The crystal structure, ferroelectric and piezoelectric properties of pyrochlore-free lead zinc niobate-lead zirconate titanate ceramics were investigated systematically as a function of Sr doping as well as thermal treatment. The results showed that the remanent polarization (P<inf>r</inf>) has decreased significantly with increase in strontium content. After annealing, the value of squareness of hysteresis loop (R<inf>sq</inf>) increased from 1.48 to 1.74 for the annealed sample. Furthermore the annealed samples exhibited larger Pr and lower coercive fields (E<inf>c</inf>) compared with as-sintered samples. The results indicated that the ferroelectric and piezoelectric properties in Sr-modified PZT-PZN were further improved by thermal annealing.
1

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