Recently, large electrocaloric effects (ECE) in antiferroelectric sol‐gel PbZr0.95Ti0.05O3 thin films and in ferroelectric polymer P(VDF‐TrFE)55/45 thin films were observed near the ferroelectric ...Curie temperatures of these materials (495 K and 353 K, respectively). Here a giant ECE (ΔT = 45.3 K and ΔS = 46.9 J K−1 kg−1 at 598 kV cm−1) is obtained in relaxor ferroelectric Pb0.8Ba0.2ZrO3 (PBZ) thin films fabricated on Pt(111)/TiOx/SiO2/Si substrates using a sol‐gel method. Nanoscale antiferroelectric (AFE) and ferroelectric (FE) phases coexist at room temperature (290 K) rather than at the Curie temperature (408 K) of the material. The giant ECE in such a system is attributed to the coexistence of AFE and FE phases and a field‐induced nanoscale AFE to FE phase transition. The giant ECE of the thin film makes this a promising material for applications in cooling systems near room temperature.
A giant electrocaloric effect at room temperature is obtained in coexisting antiferroelectric and ferroelectric phase relaxor Pb0.8Ba0.2ZrO3 thin films. Such an effect is usually obtained only at the Curie temperature. This is therefore a promising material for applications in cooling systems near room temperature.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The Ba(1−x)CaxZryTi(1−y)O3 (BCZT), a lead-free ceramic material, has attracted the scientific community since 2009 due to its large piezoelectric coefficient and resulting high dielectric ...permittivity. This perovskite material is a characteristic dielectric material for the pulsed power capacitors industry currently, which in turn leads to devices for effective storage and supply of electric energy. After this remarkable achievement in the area of lead-free piezoelectric ceramics, the researchers are exploring both the bulk as well as thin films of this perovskite material. It is observed that the thin film of this materials have outstandingly high power densities and high energy densities which is suitable for electrochemical supercapacitor applications. From a functional materials point of view this material has also gained attention in multiferroic composite material as the ferroelectric constituent of these composites and has provided extraordinary electric properties. This article presents a review on the relevant scientific advancements that have been made by using the BCZT materials for electric energy storage applications by optimizing its dielectric properties. The article starts with a BCZT introduction and discussion of the need of this material for high energy density capacitors, followed by different synthesis techniques and the effect on dielectric properties of doping different materials in BCZT. The advantages of thin film BCZT material over bulk counterparts are also discussed and its use as one of the constituents of mutiferroic composites is also presented. Finally, it summarizes the future prospects of this material followed by the conclusions.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Recently, AgNbO
3
antiferroelectric ceramics have attracted great attention by virtue of their characters of high energy storage density and environmental friendliness. To further optimize the ...electrical properties, in this work, Lu
2
O
3
modified AgNbO
3
ceramics were prepared via conventional solid state method. Crystal structure and element analysis indicated the Lu
3+
ion preferred to enter the A-site when Lu
2
O
3
content was lower than 2 mol%, otherwise, it was more likely to form LuNbO
4
or Lu
3
NbO
7
-based solid solutions. Remarkably improved stability of antiferroelectric phase was observed once Lu
3+
ions enter into the A-site, on account of the decrease of cell volume and tolerance factor. As a consequence, an enhanced recoverable energy storage density (
W
rec
) of 3.5 J/cm
3
was achieved in 1 mol% Lu
2
O
3
modified AgNbO
3
ceramics at 210 kV/cm, which is superior to the other lead-free ceramics under moderate electric field (< 220 kV/cm). It is believed our study will provide a good reference for the development of AgNbO
3
-based dielectric capacitors.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
((Bi0.5Na0.5TiO3)0.88-(BaTiO3)0.12)(1-x)-(LiNbO3)x (x = 0.0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, and 0.07; abbreviated as LiNbO3-doped BNT-BT) ceramics possessing many excellent performances (large ...electrostrain, negative electrocaloric effect and energy storage density with high efficiency) was fabricated by the conventional solid-state reaction method. A large electrostrain (maximum ~ 0.34% at 100 kV/cm and room temperature) with high thermal stability over a broad temperature range (~80 K) is obtained at x = 0.03. A large energy storage density (maximum Wenergy ~ 0.665 J/cm3 at 100 kV/cm and room temperature) with a high efficiency (η ~ 49.3%) is achieved at x = 0.06. Moreover, a large negative electrocaloric (EC) effect (maximum ΔT ~ 1.71 K with ΔS ~ - 0.22 J/(K kg) at 70 kV/cm)) is also obtained at x = 0.04. Phase transition (from ferroelectric to antiferroelectric and then to relaxor) induced by increasing the doping amount of LiNbO3 plays a very key role on the optimization of these performances. These findings and breakthroughs make the LiNbO3-doped BNT-BT ceramics very promising candidates as multifunctional materials.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The AgNbO3 antiferroelectric (AFE) ceramics have attracted increasing attention for their high energy storage performance and environmentally friendly characters. In this work, Ag1–2xBaxNbO3 ceramics ...were successfully prepared by the conventional solid-state reaction method. The effect of Ba-modification on phase structure, microstructure, and electric properties was systematically investigated. The introduction of Ba2+ ion led to complex cell parameter evolution and significant refinement of grain size. Room temperature dielectric permittivity increased obviously from ~260 for the pure AgNbO3 counterpart to ~350 for those after adding a small amount of Ba element. Slim P-E hysteresis loops with improved AFE phase were achieved after Ba modification, due to the decrease of tolerance factor. A high recoverable energy density up to 2.3 J/cm3 with energy efficiency of 46% can be obtained for the composition of Ag0.96Ba0.02NbO3, in correlation with the enhanced AFE stability, reduced Pr, increased Pm and decreased ΔE. Moreover, the Ag0.96Ba0.02NbO3 ceramics also exhibited excellent temperature stability in both energy density and efficiency with small variation of < 5% over 20–120 ℃. The results suggest that the electric properties of AgNbO3 system can be largely tuned after Ba modification, making it a promising candidate for energy storage applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Relaxor (Bi1/2Na1/2)0.94Ba0.06(1-1.5x)LaxTiO3 (x = 0, 0.03, 0.06, 0.09) ceramics (La-doped BNT-6BT) with composition close to the morphotropic phase boundary (MPB) were successfully prepared by using ...the conventional solid state reaction method. All samples present almost a pure perovskite phase with the coexistence of tetragonal and rhombohedral. With the increase of La doping content, the degree of the dielectric relaxor dispersion around the dielectric peak which is close to the room temperature increases, and also the transition temperature of ferroelectric-to-relaxor (TF-R) shifts 120K towards a lower temperature at x = 0.09. The maximum value of the temperature change (ΔT) of the electrocaloric (EC) effect decreases sharply from 1.1K at x = 0–0.064K at x = 0.09. A large positive EC effect (maximum ΔT ~ 0.44K) in a broad temperature range (~ 90K) close to room temperature is achieved at x = 0.03, indicating that it is a promising lead-free material for application in solid state cooling system. Moreover, it is found that the Maxwell relationship can be well used to assess the EC effects of the La-doped BNT-6BT ceramics when the operating temperature is higher than that of the TF-R, indicating that these relaxor ceramics would perform as an ergodic.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Mg3Sb2-based compounds by virtue of nontoxicity and low-cost have become a promising class of candidates for midtemperature thermoelectric power generation. Here, we successfully fabricated n-type ...Mg3Sb2-based materials using an inexpensive and efficient approach of one-step ball milling and spark plasma sintering, and demonstrate that a complementary and favorable effect of multiple elements coalloying/-doping leads to an excellent thermoelectric performance. The intrinsic p-type conducting behavior for Mg3Sb2 could be changed to n-type through Bi and Se coalloying on Sb sublattices with excess Mg, resulting from the suppression of Mg vacancies and the formation of Mg interstitial. Furthermore, Mn doping on Mg sublattices could soften the chemical bonds, leading to the increase of carrier mobility and concentration simultaneously. Additionally, multielement coalloying/-doping could significantly increase the lattice disorder, which undoubtedly strengthens the phonon scattering and readily results in a suppressed lattice thermal conductivity. As a result, a highest ZT value of 1.6 at 723 K and an average ZT value up to 1.1 were obtained in the temperature range of 323–723 K in the Mg3.18Mn0.02Sb1.5Bi0.49Se0.01 sample, which is one of the highest values among the Te free Mg3Sb2. This work could give guidance for improving the thermoelectric performance of Zintl phase materials or even others using the multielement codoping/-alloying strategy.
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IJS, KILJ, NUK, PNG, UL, UM
Dielectric capacitors are widely used in pulse power systems, electric vehicles, aerospace, and defense technology as they are crucial for electronic components. Compact, lightweight, and diversified ...designs of electronic components are prerequisites for dielectric capacitors. Additionally, wide temperature stability and high energy storage density are equally important for dielectric materials. Ferroelectric materials, as special (spontaneously polarized) dielectric materials, show great potential in the field of pulse power capacitors having high dielectric breakdown strength, high polarization, low-temperature dependence and high energy storage density. The first part of this review briefly introduces dielectric materials and their energy storage performance. The second part elaborates performance characteristics of various ferroelectric materials in energy storage and refrigeration based on electrocaloric effect and briefly shed light on advantages and disadvantages of various common ferroelectric materials. Especially, we summarize the polarization effects of underlying substrates (such as GaN and Si) on the performance characteristics of ferroelectric materials. Finally, the review will be concluded with an outlook, discussing current challenges in the field of dielectric materials and prospective opportunities to assess their future progress.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Abstract
BaTi
1−x
Sn
x
O
3
(BTSn, 0 ≤ x ≤ 0.30) ceramics were prepared by both the conventional sintering (CS) and sparking plasma sintering (SPS). Composition, temperature and grain size dependences ...of the nonlinear dielectric behaviors were systematically studied. BTSn was found to have especially large tunability (≥90%), which is larger than most other Pb-free systems, and is comparable to Pb-based relaxors. The high dielectric tunability in BTSn is attributed to its specific domain structures. Besides, temperature dependent tunability of BTSn presents a dispersed behavior and the dispersion is enhanced with the increase of Sn
4+
concentrations, which is explained by the compositional fluctuation model.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Transparent relaxor ferroelectrics, (K₀.₅Na₀.₅)₀.₉Sr₀.₁Nb₀.₉Ti₀.₁O₃–x%Bi₂O₃ (x = 0, 0.5, 1.0, 1.5, and 2, abbreviated as KNSNT-10x), were fabricated using a pressureless sintering method. With the ...modification of Bi₂O₃, the crystal phase of KNSNT ceramics transformed from tetragonal to cubic-like symmetry, and dielectric behaviors became more relaxor like. These changes could reduce the light scattering arisen from birefringence and long-range ordering structure, thus enhancing the optical properties. For KNSNT-10 transparent ceramics, fingerprint morphological nanodomains were observed in the transmission electron microscope image, which made the ceramics sensitive to electric field. Therefore, a large effective linear electro-optic coefficient of 26.1 pm/V was obtained for the KNSNT-10 ceramics, and it is higher than the value (19.9 pm/V) for LiNbO₃ single crystal.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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