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1.
In this work, 0.8(K2O-Na2O-2Nb2O5)?0.2((1-x)B2O3-xP2O5) (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) glass-ceramics have been fabricated. The effects of P2O5 on the microstructure and properties of the glass-ceramics were comprehensively studied. The addition of P2O5 promotes the transition of the glass network structure from a negatively charged [B?4]- tetrahedron to an electrically neutral [BP?4] tetrahedron. With the increase of P2O5 content, the formation of K2B4O7 is inhibited, with major phase of Na0.9K0.1NbO3 and minor phase of K2B4O7. It is found that the band gap width of the glass-ceramics increases from 3.34 eV to 3.52 eV firstly and then decreases to 3.43 eV. The grain size of the glass-ceramics decreases from 150 nm to 50 nm. High optical transmittance (63%), large discharge energy density (4.58 J/cm3) and large energy storage efficiency (98%) have been simultaneously obtained for K2O-Na2O-Nb2O5-B2O3-P2O5 glass-ceramics, which are potential for the applications of the transparent pulse capacitors.  相似文献   

2.
《Ceramics International》2023,49(20):32789-32798
Crystallization kinetics in ZrO2-modified glass-ceramics, (35-x)Na2O–5K2O–40Nb2O5–20SiO2-xZrO2 (x = 0, 1, 3, 5, 10 mol%), is analyzed by crystallization activation energy Ec and kinetic parameter k. A large kinetic parameter k of 1.657 × 1025 is found for the sample with x = 1, which indicates a high tendency toward crystallization. NaNbO3 is formed as the major phase, and its crystallinity changes significantly by the addition of ZrO2. It is found that the dielectric permittivity and maximum polarization are affected by crystallinity. Large domains are formed, and a relaxation process appears at high frequencies. In addition, the breakdown strength (BDS) is affected by the strong electric field distortion rather than the resistance in this system. Complex impedance analysis shows that resistance decreases with the addition of ZrO2. The electric field distortion of the glass-ceramics is simulated by COMSOL. A low interfacial polarization activation energy Ea of 0.821 eV is achieved by the addition of ZrO2. The maximum pulse power density reaches 90 MW/cc at 350 kV/cm for the sample with x = 10, and the pulse energy density attains 0.91 J/cm3 at 300 kV/cm for the sample with x = 1. Light transmittance is achieved because of the low crystallinity and the disappearance of cristobalite SiO2 in the Na2O–K2O–Nb2O5–SiO2 glass-ceramics.  相似文献   

3.
Manipulating the critical switching field between antiferroelectric (AFE) state and ferroelectric (FE) is an important concept for tuning the energy storage performance of AFEs. As one of the lead-based AFE systems, Pb(Lu1/2Nb1/2)O3 promises high potential in the miniaturization of pulsed power capacitors, but the extremely high critical switching field and low induced saturated polarization demonstrate severe drawbacks with respect to temperature stability and flexibility. Here, A-site Ba2+ doping engineering is used to effectively reduce the critical switching field and improve the saturated polarization in BaxPb1-x(Lu1/2Nb1/2)O3 (0.01 ≤ x ≤ 0.08, abbreviated as xBa-PLN) ceramics. We found the AFE-FE phase transition can be occurred at 80ºC with a high energy storage density of 4.03 J/cm3 for Ba0.06Pb0.94(Lu1/2Nb1/2)O3 ceramic. Our results show that Ba2+ additions destroy the antiparallel structure of AFE phase, and finally reduce the critical switching field, demonstrating a potential alternative to modulate the energy storage performance of AFEs.  相似文献   

4.
《Ceramics International》2022,48(1):776-783
High-performance lead-free dielectric containers have excellent energy storage performance such as higher power density and energy density. While being eco-friendly materials, lead-free dielectric materials are more suitable for pulse power systems than other dielectric materials. In this study, Ta5+and Bi3+ ions were introduced into the A site and B site of the NaNbO3 matrix. The introduction of Bi3+ ions induced the formation of a vacancy in the A site, yielding Na(1-3x)BixNb0.85Ta0.15O3 (NBNT, x = 0.05, 0.08, 0.11, 0.14) ceramics. The recoverable energy density (Wrec) and the energy storage efficiency (η) were highest for the Na0.67Bi0.11Nb0.85Ta0.15O3 ceramic, with values of 3.37 J/cm3 and 89% respectively. Batteries employing the Na0.67Bi0.11Nb0.85Ta0.15O3 ceramic achieved a current density of 830.4 A/cm2, an energy density of 49.8 MW/cm3 and 60.2 ns discharge time. These results show that the Na0.67Bi0.11Nb0.85Ta0.15O3 ceramic is an effective energy storage material with broad application prospects.  相似文献   

5.
Dielectric capacitors with decent energy storage and fast charge-discharge performances are essential in advanced pulsed power systems. In this study, novel ceramics (1-x)NaNbO3-xBi(Ni2/3Nb1/3)O3(xBNN, x = 0.05, 0.1, 0.15 and 0.20) with high energy storage capability, large power density and ultrafast discharge speed were designed and prepared. The impedance analysis proves that the introducing an appropriate amount of Bi(Ni0·5Nb0.5)O3 boosts the insulation ability, thus obtaining a high breakdown strength (Eb) of 440 kV/cm in xBNN ceramics. A high energy storage density (Wtotal) of 4.09 J/cm3, recoverable energy storage density (Wrec) of 3.31 J/cm3, and efficiency (η) of 80.9% were attained in the 0.15BNN ceramics. Furthermore, frequency and temperature stability (fluctuations of Wrec ≤ 0.4% over 5–100 Hz and Wrec ≤ 12.3% over 20–120 °C) were also observed. The 0.15BNN ceramics exhibited a large power density (19 MW/cm3) and ultrafast discharge time (~37 ns) over the range of ambient temperature to 120 °C. These enhanced performances may be attributed to the improved breakdown strength and relaxor behavior through the incorporation of BNN. In conclusion, these findings indicate that 0.15BNN ceramics may serve as promising materials for pulsed power systems.  相似文献   

6.
《Ceramics International》2022,48(13):18730-18738
A series of new negative temperature coefficient (NTC) thermal materials based on (Ba0.85Ca0.15)1-xCex/2(Zr0.1Ti0.9)O3 (0.00 ≤ x ≤ 0.20) ceramics were synthesized by a solid-state method. X-ray diffraction, scanning electron microscope and X-ray photoelectron spectroscopy were used to demonstrate the crystal structure, morphology, and composition of the (Ba0.85Ca0.15)1-xCex/2(Zr0.1Ti0.9)O3 ceramics, which were composed of solid solution based on the BaTiO3 phase. The average grain size of doped ceramic samples experienced the process of first decreasing and then increasing. The doping of Ce has reduced the sintering temperature. The temperature-dependent resistance analysis revealed that with the change of doping amount x, the thermal constant B300/1200 (1.21 × 104–1.13 × 104 K) and the activation energy Ea300/1200 (0.9777–1.0471eV) was initially increased to maximum values at x = 0.05, followed by the decreasing when x > 0.05. It has been established that the concentration of oxygen vacancies is affected by the transition between Ce4+ and Ce3+ provided by high levels of Ce doping. (Ba0.85Ca0.15)1-xCex/2(Zr0.1Ti0.9)O3 ceramics exhibited excellent negative temperature characteristics in the range of 300–1200 °C. Moreover, the temperature resistance linearity was improved after samples were aged. Hence, the (Ba0.85Ca0.15)1-xCex/2(Zr0.1Ti0.9)O3 ceramics were regarded as a promising material for high-temperature NTC thermistors in a wide temperature range.  相似文献   

7.
In this study, the phase structure, microstructure and dielectric properties of Bi0.5(Na0.78K0.22)0.5(Ti1-xNbx)O3 lead-free ceramics prepared by traditional solid phase sintering method were studied. The second phase pyrochlore bismuth titanate (Bi2Ti2O7) was produced in the system after introduction of Nb5+. The dielectric constant of the sample (x = 0.03) sintered at 1130 °C at room temperature reached a maximum of 1841, and the dielectric loss was 0.045 minimum. It had been found that the K+ and Nb5+ co-doped Bi0.5Na0.5TiO3 (BNT) lead-free ceramics exhibited outstanding dielectric-temperature stability within 100–400 °C with Tcc ≤±15%. Result of this research provides a valuable reference for application of BNT based capacitors in high temperature field.  相似文献   

8.
A series of lead-free (Bi0.5Na0.5)0.94Ba0.06Ti1-x(Y0.5Nb0.5)xO3 (for 0 ≤ x ≤ 0.03) perovskite ceramics were fabricated using a solid-state reaction technique. The effects of (Y0.5Nb0.5)4+ ions doping on phase structure, piezoelectric properties, AC impedance, and fatigue resistance were systematically studied. Crystal structure as a function of the composition revealed a single perovskite lattice structure with dense micromorphology. The transition temperature of the non-ergodic and ergodic relaxor ferroelectric phase shifted to near ambient temperature with increasing composition, which was related to the destruction of the long-range ordered ferroelectric domains. Hence, the transformation of ferroelectric-to-relaxor phase was easier under applied electric field at room temperature. The ceramic for x = 0.01 composition attained a large unipolar strain of ~ 0.452% with a corresponding normalized strain (d33*) of ~ 603 pm/V under applied 75 kV/cm field. Besides, the excellent fatigue resistance of the sample was obtained after 105 switching cycles under 70 kV/cm. These phenomena demonstrated that (Bi0.5Na0.5)0.94Ba0.06Ti1-x(Y0.5Nb0.5)xO3 ceramics might be suitable for a wide range of electronic equipment applications such as actuators and sensors.  相似文献   

9.
Dependence of electrical properties on the structural characteristics of Li0.04(K0.5Na0.5)0.96(Nb1?ySby)O3 (LKNNS (x = 0, 0.00  y  0.10)) and [Li0.04(K0.5Na0.5)0.96?xAgx](Nb0.925Sb0.075)O3 (LKNANS (0.01  x  0.05, y = 0.075)) were investigated. The oxygen octahedral distortion was dependent on Ag+ and/or Sb5+ content which affected to the phase transition temperature of LKNNS and LKNANS ceramics. The orthorhombic–tetragonal and tetragonal–cubic phase transition temperatures (TO–T, TC) of the specimens were decreased with increasing of average octahedral distortion. With increasing of Sb5+ content, the electromechanical coupling factor (kp), piezoelectric constant (d33) and dielectric constant (?r) of the sintered specimens were increased up to y = 0.075, and then decreased. These results could be attributed to the shift of TO–T to near room temperature for Li0.04(K0.5Na0.5)0.96(Nb0.0925Sb0.075)O3.  相似文献   

10.
This study investigated the phase transition behavior and electrical properties of (K0.5Na0.5)(Nb1-xZrx)O3 (KNN?100xZ) and (K0.5Na0.5)NbO3yBaZrO3 (KNN–100yBZ) lead–free piezoelectric ceramics. The phase transitions in crystal structures were compared in KNN ceramics between single Zr4+ doping and Ba2+Zr4+ co?doping. Piezoelectric properties such as the piezoelectric constant (d33) and electromechanical coupling factor (kp) are optimized for KNN?6BZ ceramics and were clarified via the polymorphic phase transition from the orthorhombic to pseudocubic phase. The fitted degree of diffuseness (γ) for a phase transition from the modified Curie–Weiss law indicated that KNN ceramics as ferroelectrics are gradually transformed through BaZrO3 modification. Accordingly, the enhanced strain properties at y = 0.08 consist of coexisting ferroelectric domains and polar nanoregions that are supported by ferroelectric–to–relaxor crossover in KNN?100BZ ceramics.  相似文献   

11.
The ordering behaviour of Ba(Mg1/3Nb2/3)O3 ceramics (BMN) substituted by La3+, Na+, K+ was investigated using X-ray powder diffraction and transmission electron microscopy. The 1:2 ordered structure of BMN can be transformed to 1:1 ordered structure by substituting a small amount of La cation ion into the A-site. Moreover, the degree of ordering was increased with La content in the compound, and reached almost unity at [La] = 50 mol%. When the La ion in (Ba1−xLax)(Mg(1+x)/3Nb(2−x)/3)O3 (BLMN) was substituted by Na or K ions, the 1:1 ordered structure of BLMN was transformed into the 1:2 ordered structure. The degree of 1:2 ordering was influenced by the sintering temperature and the size difference between the A and B site ions.  相似文献   

12.
《Ceramics International》2016,42(4):4648-4657
Lead-free (1−x)(K0.37Na0.63)NbO3-xCa(Sc0.5Nb0.5)O3 (x=0.050, 0.070, 0.090, 0.095 and 0.100) transparent ferroelectric ceramics have been fabricated by pressureless sintering procedure. Transmittance of 0.91(K0.37Na0.63)NbO3-0.09Ca(Sc0.5Nb0.5)O3 ceramics sintered in sealed alumina crucible was 15% higher than those sintered unsealed in air. By increasing the content of Ca(Sc0.5Nb0.5)O3, the phase structure of (K0.37Na0.63)NbO3 ceramics transformed from orthorhombic to tetragonal symmetry first and then to pseudo cubic symmetry. The 0.91(K0.37Na0.63)NbO3-0.09Ca(Sc0.5Nb0.5)O3 ceramics exhibited high density (98%), high transmittance (60%) in the near-IR region and relatively good electrical properties (εr=1914, tanδ=0.037, Tc=147 °C, Pr=6.88 μC/cm2, Ec=8.49 kV/cm). Meanwhile, the introduction of Ca(Sc0.5Nb0.5)O3 induced a composition fluctuation in the (K0.37Na0.63)NbO3 lattice and made the ceramics more relaxor-like, which would lead to a further reduction of light scattering. These results demonstrated that 0.91(K0.37Na0.63)NbO3-0.09Ca(Sc0.5Nb0.5)O3 could be promising lead-free transparent ferroelectric ceramics.  相似文献   

13.
《Ceramics International》2017,43(7):5367-5373
Lead-free piezoceramics (Na(1+x)/2Bi(1-x)/2)0.94Ba0.06Ti1-xNbxO3 (BTN100x) were prepared using conventional solid-state reaction method. The structures, field- induced strain, AC impedance of sintered ceramics were investigated. The pure perovskite solid solution BTN3 exhibited giant electric-field-induced strain of 0.478% under an electric field of 70 kV/cm at ambient temperature, meanwhile, the normalized strain (Smax/Emax) reached up to 654 pm/V. The giant strain was insensitive to temperature and exhibited excellent fatigue resistance performance within 106 switching cycles, making it a promising candidate material for actuator applications. Complex AC impedance spectra confirmed the contribution of grain effect to resistivity behavior. The field-induced giant strain was attributed to the phase transition between ferroelectrics and relaxor ferroelectrics induced by introducing Nb2O5.  相似文献   

14.
A series of novel lead-free energy storage ceramics, (0.67-x)BiFeO3-0.33BaTiO3-xBaBi2Nb2O9 (BF-BT-xBBN), were fabricated by traditional solid-state reaction, where bismuth layer-structured BaBiNb2O9 was incorporated into perovskite-structured BiFeO3–BaTiO3 ceramic as an additive. The addition of BaBi2Nb2O9 increased the relaxor behavior and breakdown strength of BF-BT ceramics due to the formation of polar nanoregionals (PNRs), inducing enhanced energy storage performance. The composite ceramics, with x = 0.08, showed a large recoverable energy density (Wrec) of 3.08 J/cm3 and an outstanding energy storage efficiency (η) of 85.57% under an applied electric field of 230 kV/cm. Moreover, the composite ceramics exhibited excellent thermal stability and high stability toward different frequencies in a temperature range of 20–100 °C and a frequency range of 0.1–1500 Hz. These results demonstrate great potential of novel BF-BT-xBBN composite ceramics for next-generation energy storage applications.  相似文献   

15.
《Ceramics International》2022,48(2):2355-2361
This research explored the influence of Nb5+ doping on the electrical properties and microstructure of [0.852(Bi0.5Na0.5)-0.11(Bi0.5K0.5)-0.038Ba]Ti(1-x)NbxO3 (designated as BNKT-BT). The BNKT-BT samples were fabricated and the XRD results showed that the doping of Nb5+ ions induced a transformation from the coexistence of both rhombohedral and tetragonal phase to a single pseudo cubic phase. Also, the doping of Nb5+ ions caused the temperature of ferroelectric state-ergodic relaxor state transition to decrease below the room temperature (RT). The SEM observations showed that the Nb5+ doping had a minor effect on the grain size of BNKT-BT samples. In addition, the samples achieved a large electrostrain of 0.43% (d*33 = Smax/Emax = 614 pm/V) under 7 kV/mm at RT. Moreover, the aging process employed at 80 °C for two weeks in air could effectively increase the electrostrain from 0.38% to 0.41% under 6 kV/mm (d*33 = 683 pm/V) and reduce the strain hysteresis from 57% to 34%. These results indicated that the B site doping, combined with the aging process, could provide an effective way to enhance the electrostrain performance of lead-free piezoelectric ceramics.  相似文献   

16.
《Ceramics International》2023,49(10):15304-15314
In this paper, a series of Li2Zn[Ti1-x(Co1/3Nb2/3)x]3O8 (0.0 ≤ x ≤ 0.4) ceramics were prepared via the conventional solid-state method. The influences of (Co1/3Nb2/3)4+ complex ions on the phase composition, spectral characteristics, microstructure, and microwave dielectric properties of Li2Zn[Ti1-x(Co1/3Nb2/3)x]3O8 ceramics were studied systematically. XRD analysis accompanied with Rietveld refinements showed that pure Li2ZnTi3O8 solid solution ceramics with the cubic spinel structure were obtained at x = 0.2–0.4. New Raman-active mode of about 858 cm−1 should be attributed to the vibrations of NbO6 due to the high bond energy of Nb–O bonds, exerting a certain impact on the structure and performance of Li2Zn[Ti1-x(Co1/3Nb2/3)x]3O8 ceramics. XPS results indicated that Nb5+ ion donor suppressed the deoxidation process and therefore resulted in the disappearance of Ti3+ ion and oxygen vacancy. The downward trend variation in the εr value with the increase of (Co1/3Nb2/3)4+ content could be explained by the presence of “compressed” cations and “rattling” cations effect. In addition, the Q × f of the current ceramics was closely dependent on relative density, grain size, FWHM, and oxygen vacancy. Good combined microwave dielectric properties of εr = 24.5, Q × f = 91,250 GHz, and τf = −16.8 ppm/°C were achieved for the Li2Zn[Ti0.8(Co1/3Nb2/3)0.2]3O8 ceramic sintered at 1120 °C. High quality factor gives evidence that the Li2Zn[Ti0.8(Co1/3Nb2/3)0.2]3O8 ceramic is an appealing candidate for highly selective microwave devices.  相似文献   

17.
Three types of nanostructured systems: xNbO·(1?x)α-Fe2O3, xNbO2·(1?x)α-Fe2O3, and xNb2O5·(1?x)α-Fe2O3 were synthesized by ball milling at different molar concentrations (x=0.1, 0.3, 0.5, and 0.7). The effect of Nb valence and milling time on mechanochemical activation of these systems were studied by X-ray diffraction and the Mössbauer spectroscopy measurements. In general, Nb-substituted hematite was obtained at lower molar concentrations for all Nb oxides. For the NbO–Fe2O3 system the favorable substitution of Fe2+ for Nb2+ in the octahedral sites in the NbO lattice was observed after 12 h milling for x=0.7. In the case of the NbO2–Fe2O3 and Nb2O5–Fe2O3 systems a formation of orthorhombic FeNbO4 compound was observed, in which Fe3+ cations were detected. For the highest concentration of NbO2 (x=0.7) iron was completely incorporated into the FeNbO4 phase after 12 h milling. The molar concentrations of x=0.3 and 0.5 were the most favorable for the formation of ternary FeNbO4 compound in the Nb2O5–Fe2O3 system. Influence of ball milling on thermal behavior of the powders was investigated by simultaneous DSC–TG measurements up to 800 °C.  相似文献   

18.
《Ceramics International》2020,46(9):13159-13169
Lead-free perovskite dielectric materials for capacitors have received wide concern in recent years, but their energy storage density and efficiency still cannot meet the growing application demand for practical applications. In this work, we prepared a lead-free relaxor ferroelectric ceramic of (1-x)Bi0.47Na0.47Ba0.06TiO3-xSr(Zr0.8Nb0.16)O3, which was synthesized via a normal solid-state route. The microstructure, dielectric properties and energy storage behavior of the ceramics were explored. The ceramics can be well sintered and situated in the region where rhombohedral and tetragonal phases coexist. The addition of Sr(Zr0.8Nb0.16)O3 (SZN) significantly extends the dielectric-temperature plateau between Ts and Tm and reduces the remnant polarization Pr, but the large saturation polarization Ps is still maintained. Besides, the doping of SZN enhances the relaxation of the material and increases the dielectric breakdown strength (DBS) from 50 kV/cm (x = 0) to 100 kV/cm (x = 0.04 and 0.06). Therefore, the ceramic with x = 0.06 exhibits a high discharging efficiency (η) of 71.1% and energy density (W) of 1.56 J/cm3 at 100 kV/cm and shows the superior thermal stability with the changes in recoverable energy density (Wrec) and η of less than 10% and 30% at the temperature range of 25–180 °C and the excellent frequency stability with the variations of Wrec and η of less than 1.8% and 1% at the frequency range of 10 Hz–100 Hz.  相似文献   

19.
The influence of Nb2O5 on the structure and ionic conductivity of potassium phosphate glasses was investigated in glasses with composition xNb2O5–(100-x)[0.45K2O–0.55P2O5], x = 10–47 mol%. The Raman spectra of glasses reveal a transition from predominantly orthophosphate to predominantly niobate glass network with increasing Nb2O5 content. In the glass structure, niobium forms NbO6 octahedra which are interlinked with phosphate units for the glass containing 10 mol% Nb2O5, but for higher Nb2O5 content they become mutually interconnected via Nb-O-Nb bonds. The transport of potassium ions was found to be strongly dependent on the structural characteristics of the glass network. While the mixed niobate-phosphate glass network hinders the diffusion of potassium ions by providing traps that immobilize them and/or by blocking the conduction pathways, predominantly niobate glass network exhibits a rather facilitating effect which is evidenced in the trend of DC conductivity as well as in the features of the frequency-dependent conductivity and typical hopping lengths of potassium ions.  相似文献   

20.
Lead-free (1-x)BiFeO3-x(0.85BaTiO3-0.15Bi(Sn0.5Zn0.5)O3) [(1-x)BF-x(BT-BSZ), x=0.45-0.7] ceramic samples were prepared by solid phase sintering. It is revealed that the pure single-phase perovskite structure can be obtained in samples with x ≥ 0.6. With increasing x, the measured ferroelectric hysteresis loop becomes gradually slimmed in accompanying with reduced remnant polarization, and a clear ferroelectric-relaxor transition at x = 0.65 is identified. Furthermore, the measured electric breakdown strength can be significantly enhanced with increasing x, and the optimal energy storage performance is achieved at x = 0.65, characterized by the recoverable energy storage density up to ≈3.06 J/cm3 and energy storage efficiency as high as ≈92 %. Excellent temperature stability (25°C–110°C) and fatigue endurance (>105 cycles) for energy storage are demonstrated. Our results suggest that the BF-based relaxor ceramics can be tailored for promising applications in high energy storage devices.  相似文献   

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