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1.
The effects of acceptor doping with manganese as either MnO2 or MnNb2O6 (MnN) with CuO on the dielectric, ferroelectric, and piezoelectric properties of PIN-PMN-PT ceramics were investigated. The 2% MnNb2O6-doped PIN-PMN-PT (6Pb(Mn1/3Nb2/3)O3-25Pb(In1/2Nb1/2)O3-34Pb(Mg1/3Nb2/3)O3-35PbTiO3) ceramics possessed hard properties such as high coercive field (EC) of 11.7 kV/cm, low dielectric loss (tan δ) of 0.7%, and high electromechanical quality factor (QM) of 1011. These properties were diminished in MnO2-doped ceramics because of lower oxygen vacancy defect concentration, and exaggerated grain growth resulted in >20 µm grain size. Co-doping with 2 mol% MnNb2O6 and 0.5 mol% CuO retained hardened properties such as high EC of 9.6 kV/cm, low tan δ of 0.6%, and high QM of 1029. MnNb2O6-doped and MnNb2O6 + Cu co-doped ceramics display excellent figures of merit for resonance and off-resonance applications as well as high energy conversion efficiencies which make them promising candidates for high-power transducer elements.  相似文献   

2.
x% mol MnO2‐doped Ba0.925Ca0.075TiO3 ceramics (abbreviated as BCT‐Mnx, x=0‐1.5) were synthesized by conventional solid‐state reaction method. The effects of MnO2 addition and (Ba+Ca)/Ti mole ratio (A/B ratio) on the microstructure and electrical properties of the ceramics were investigated. The internal bias filed Ei was determined from the asymmetrical polarization hysteresis loops and found to increase with the doping concentration of MnO2. High mechanical quality factors (Qm>1200) and low dielectric loss (tanδ<0.5%) were found in the BCT‐Mn0.75 and BCT‐Mn1.0 ceramics with Ei>3 kV/cm, meanwhile, the piezoelectric and electromechanical properties were found to decrease compared with the pure BCT, exhibiting a typical characteristic of “hard” behavior. Of particular interest is that the microstructure of BCT‐Mn0.75 ceramics could be controlled by changing the A/B ratio, where enhanced piezoelectric coefficient d33 on the order of 190 pC/N was obtained in the BCT‐Mn0.75 ceramics with A/B=1.01 due to its fine‐grained microstructure, with yet high Qm, being on the order of 1000. The high d33 and Qm in MnO2‐doped BCT ceramics make it a promising candidate for high power piezoelectric applications.  相似文献   

3.
The relationship between the piezoelectric properties and the structure/microstructure for 0.05Bi(Mg2/3Nb1/3)O3‐(0.95‐x)BaTiO3xBiFeO3 (BBFT,= 0.55, 0.60, 0.63, 0.65, 0.70, and 0.75) ceramics has been investigated. Scanning electron microscopy revealed a homogeneous microstructure for < 0.75 but there was evidence of a core‐shell cation distribution for = 0.75 which could be suppressed in part through quenching from the sintering temperature. X‐ray diffraction (XRD) suggested a gradual structural transition from pseudocubic to rhombohedral for 0.63 < < 0.70, characterized by the coexistence of phases. The temperature dependence of relative permittivity, polarization‐electric field hysteresis loops, bipolar strain‐electric field curves revealed that BBFT transformed from relaxor‐like to ferroelectric behavior with an increase in x, consistent with changes in the phase assemblage and domain structure. The largest strain was 0.41% for x = 0.63 at 10 kV/mm. The largest effective piezoelectric coefficient (d33*) was 544 pm/V for = 0.63 at 5 kV/mm but the largest Berlincourt d33 (148 pC/N) was obtained for x = 0.70. We propose that d33* is optimized at the point of crossover from relaxor to ferroelectric which facilitates a macroscopic field induced transition to a ferroelectric state but that d33 is optimized in the ferroelectric, rhombohedral phase. Unipolar strain was measured as a function of temperature for = 0.63 with strains of 0.30% achieved at 175°C, accompanied by a significant decrease in hysteresis with respect to room temperature measurements. The potential for BBFT compositions to be used as high strain actuators is demonstrated by the fabrication of a prototype multilayer which achieved 3 μm displacement at 150°C.  相似文献   

4.
A new lead‐potassium‐free ceramic of (0.9‐x)NaNbO3‐0.1BaTiO3‐xNaSbO3 (NN‐BT‐xNS) was successfully prepared via a solid‐state reaction method. The microstructure, phase structure, dielectric, ferroelectric, and piezoelectric properties were investigated as a function of NS content. The substitution of NS for NN was found to dramatically change the grain morphology from cube‐like grains typical for alkaline niobate‐based ceramics to conventional sphere‐like grains especially for Pb‐based perovskite ceramics. A normal to relaxor ferroelectric phase transformation was accompanied by a tetragonal (T) to rhombohedral (R) phase transition. A composition‐temperature phase diagram demonstrated a vertical morphotropic phase boundary between T and R phases in the composition range of x=0.03‐0.04, where optimum electrical properties of d33=252 pC/N, kp=36%, Qm=168, =2063, and Tc=109°C were obtained in the x=0.035 ceramic sintered at 1260°C. Particularly, excellent temperature insensitivity of small‐signal piezoelectric properties suggested large application potentials in various actuators and sensors in comparison with other typical lead‐free materials.  相似文献   

5.
CuO‐added (1‐x)KNbO3x mol%BaZrO3 ceramics with 0.0≤x≤7.0 were sintered at 960°C. Large double polarization vs electric field (P‐E) and sprout‐shaped strain vs electric field (S‐E) hysteresis curves were obtained from the specimens with x≤2.0. They exhibited large polarizing electric fields (EP) owing to the presence of a large number of defect dipoles (PDs) that formed between Cu2+ ions and oxygen vacancies. Small double P‐E hysteresis curves were observed for the specimens with x≥3.0 with reduced EP because of the decreased number of PDs and the presence of a polymorphic phase structure containing both orthorhombic and pseudocubic structures. In particular, the specimen with x=5.0 exhibited a large strain of 0.16% at 8.0 kV/mm with a small EP of 1.2 kV/mm and good fatigue property: this specimen maintained a strain of 0.13% at 6.0 kV/mm after 106 cycles of 3.0 kV/mm.  相似文献   

6.
Defect greatly affects the microscopic structure and electrical properties of perovskite piezoelectric ceramics, but the microscopic mechanism of defect‐driven macroscopic properties in the materials is not still completely comprehended. In this work, K0.5Na0.5NbO3+x mol CuSb2O6 lead‐free piezoelectric ceramics were fabricated by a solid‐state reaction method and the defect‐driven evolution of piezoelectric and ferroelectric properties was studied. The addition of CuSb2O6 induces the formation of dimeric (DC1) and trimeric (DC2) defect dipoles. At low doping concentration of CuSb2O6 (0.5‐1.0 mol%), DC1 and DC2 coexist in the ceramics and harden the ceramics, inducing a constricted double P‐E loop and high Qm of 895 at x=0.01. However, DC2 becomes more dominant in the ceramics with high concentration of CuSb2O6 (≥1.5 mol%) and thus leads to softening behavior of piezoelectricity and ferroelectricity as compared to the ceramic with x=0.01, giving a single slanted P‐E loop and relatively low Qm of 206 at x=0.025. All ceramics exhibit relatively high d33 of 106‐126 pC/N. Our study shows that the piezoelectricity and ferroelectricity of K0.5Na0.5NbO3 ceramics can be tailored by controlling defect structure of the materials.  相似文献   

7.
The luminescent‐ferroelectic materials based on Sr1.90Ca0.15Na0.9Nb5O15 (SCNN) matrix doping with Eu3+ were synthesized by the conventional solid‐state reaction method. The crystal structure, photoluminescence, thermal stability, dielectric, ferroelectric, and piezoelectric behaviors were systematically investigated. XRD results revealed that Eu3+ introduction could induce the tungsten bronze phase transition from orthorhombic to tetragonal structures. The dielectric spectra of all specimens showed two broad dielectric anomalies: a high‐temperature ferroelectric phase transition (Tc) and a low‐temperature ferroelastic phase transition (Ts), both of which were suppressed at higher Eu3+ concentrations. The enhanced electrical properties were obtained in a proper Eu3+ concentration range of 0.03‐0.05. For all SCNN:xEu3+ samples, the strong red emission peak at 617 nm originating from the electric dipole transition of 5D07F2 was excited by different light excitations of 395 or 463 nm. Our results demonstrated that Eu3+‐doped SCNN materials might have promising potential in advanced multifunctional optoelectronic applications.  相似文献   

8.
Continued reduction in length scales associated with many ferroelectric film‐based technologies is contingent on retaining the functional properties as the film thickness is reduced. Epitaxial and polycrystalline lead magnesium niobate‐lead titanate (70PMN‐30PT) thin films were studied over the thickness range of 100‐350 nm for the relative contributions to property thickness dependence from interfacial and grain‐boundary low permittivity layers. Epitaxial PMN‐PT films were grown on SrRuO3/(001)SrTiO3, while polycrystalline films with {001}‐Lotgering factors >0.96 were grown on Pt/TiO2/SiO2/Si substrates via chemical solution deposition. Both film types exhibited similar relative permittivities of ~300 at high fields at all measured thicknesses with highly crystalline electrode/dielectric interfaces. These results, with the DC‐biased and temperature‐dependent dielectric characterization, suggest irreversible domain wall mobility is the major contributor to the overall dielectric response and its thickness dependence. In epitaxial films, the irreversible Rayleigh coefficients reduced 85% upon decreasing thickness from 350 to 100 nm. The temperature at which a peak in the relative permittivity is observed was the only measured small signal quantity which was more thickness‐dependent in polycrystalline than epitaxial films. This is attributed to the relaxor nature present in the films, potentially stabilized by defect concentrations, and/or chemical inhomogeneity. Finally, the effective interfacial layers are found to contribute to the measured thickness dependence in the longitudinal piezoelectric coefficient.  相似文献   

9.
Multiferroic materials displaying coupled ferroelectric and ferromagnetic order parameters could provide a means for data storage whereby bits could be written electrically and read magnetically, or vice versa. Thin films of Aurivillius phase Bi6Ti2.8Fe1.52Mn0.68O18, previously prepared by a chemical solution deposition (CSD) technique, are multiferroics demonstrating magnetoelectric coupling at room temperature. Here, we demonstrate the growth of a similar composition, Bi6Ti2.99Fe1.46Mn0.55O18, via the liquid injection chemical vapor deposition technique. High‐resolution magnetic measurements reveal a considerably higher in‐plane ferromagnetic signature than CSD grown films (MS=24.25 emu/g (215 emu/cm3), MR=9.916 emu/g (81.5 emu/cm3), HC=170 Oe). A statistical analysis of the results from a thorough microstructural examination of the samples, allows us to conclude that the ferromagnetic signature can be attributed to the Aurivillius phase, with a confidence level of 99.95%. In addition, we report the direct piezoresponse force microscopy visualization of ferroelectric switching while going through a full in‐plane magnetic field cycle, where increased volumes (8.6% to 14% compared with 4% to 7% for the CSD‐grown films) of the film engage in magnetoelectric coupling and demonstrate both irreversible and reversible magnetoelectric domain switching.  相似文献   

10.
The phase structure, dielectric, ferroelectric, and piezoelectric properties of (1?2x)BiScO3xPbTiO3xPbMg1/3Nb2/3O3 ceramics (x = 0.30‐0.46) were studied. It was found that an increase in x leads to a structural phase transition between the rhombohedral and tetragonal phase via an intermediate monoclinic phase and to a crossover from the nonergodic relaxor state to the ferroelectric one. It was proposed that at x > 0.42 the phase transition changes from second to first order. The assumption about the existence of a tricritical point on the phase diagram at x ≈ 0.42 with the enhanced dielectric response has been made. The observed structure‐property relationships of the studied solid solutions are discussed. It is shown that the solid solutions with x = 0.42 are characterized by the high piezoelectric parameters (d33 = 509 pC/N, d31 = ?178 pC/N, dh = 153 pC/N), which makes possible their applications in sonar equipment.  相似文献   

11.
Donor doping is commonly applied for softening of the piezoelectric and dielectric properties and facilitation of polarization switching in the ubiquitous Pb(Zr,Ti)O3 [PZT] ceramics. The origin of the donor‐dopant effects is not entirely clear. (Pb,Ba)ZrO3 [PBZ] is a related ferroelectric material, its perovskite A‐site being partially occupied by the larger Ba+2 cation, less prone to evaporation than Pb+2, and the B‐site is occupied entirely by the valency‐stable Zr+4. Here we report on our studies of Nb+5 doping effects in (Pb,Ba)ZrO3. Similarly, to past observations on La+3 and Nb+5 doped PZT, we find a strong reduction in relative density of PBZ when the doping is <0.5 atomic %. This is accompanied by lattice parameter reduction, enhanced PbO loss, smaller grain size and deterioration of dielectric, piezoelectric and polarization switching properties, the latter being opposite of expected softening effect. All those observations can be interpreted in terms of the Nb entering A‐site at small concentrations. This is supported by ab‐inito calculations and analysis of the possible defect reaction equations. The structure and microstructure of PBZ with Nb>0.2% are consistent with Nb+5 entering the B‐site and softening effects are observed. The study supports the scenario of hardening due to domain walls pinning by VPbVO divacancies and softening upon decrease in their concentration.  相似文献   

12.
(1?x)Bi1/2Na1/2TiO3xPbMg1/3Nb2/3O3[(1?x)BNT‐xPMN] ceramics have been fabricated via a conventional solid‐state method for compositions x ≤ 0.3. The microstructure, phase structure, ferroelectric, and dielectric properties of ceramics were systematically studied as high‐temperature capacitor materials. XRD pattern certified perovskite phase with no secondary phase in all compositions. As PMN concentration increased, the phase of (1?x)BNT‐xPMN ceramics transformed from ferroelectric to relaxor gradually at room temperature, with prominent enhancement of dielectric temperature stability. For the composition x = 0.2, the temperature coefficient of capacitance (TCC) was <15% in a wide temperature range from 56 to 350°C with high relative permittivity (>3300) and low dielectric loss (<0.02) at 150°C, which indicated promising future for (1?x)BNT‐xPMN system as high‐temperature stable capacitor materials.  相似文献   

13.
Bi0.5Na0.5TiO3-based ceramics with high remnant polarization Pr have shown outstanding potential in the application of high-power ferroelectric transducers. However, low depolarization temperature Td is an obstacle for their application. Here, a composition design strategy was proposed to simultaneously improve the Td and Pr in BNT-based materials. Ultrahigh Pr of 40.56 µC/cm2 and relative high Td of 184°C were synergistically achieved in (Bi0.5Na0.5)(Ti0.995Mn0.005)O3 (BNMT) ceramics by adding 1.0 mol% BiGaO3 (BG), which is superior to other reported lead-free systems. The excellent ferroelectric properties were attributed to strengthen ferroelectric order as evidenced by increased rhombohedral distortion. Meanwhile, the enhanced depolarization temperature, increasing from 168°C for x = 0% to 184°C for x = 1.0%, can be ascribed to the suppression of the thermal-induced ferroelectric-relaxor phase transition by adding BG. Those results enable the BNMT-BG systems ceramics to be an attractive candidate for application in high-power supplies.  相似文献   

14.
xPb(Zn0.5Te0.5)O3–(1?x)Pb(Zr0.5Ti0.5)O3 (PZnTe–PZT) ceramics were prepared by the solid‐state reaction method. The phase structure, microstructure, ferroelectric and dielectric properties and thermal expansion properties were systematically investigated. X‐ray diffraction analysis showed the morphotropic phase boundary (MPB) existed at the composition of x = 0.08, which was the coexistence of the rhombohedral phase and the tetragonal phase. The grain size of ceramics decreased rapidly from 10‐20 μm to 1‐3 μm when the PZnTe was added in. The PZnTe–PZT ceramics at the MPB composition showed the largest high field effective piezoelectric coefficient and the lowest strain hysteresis H. The dielectric permittivity and phase transition temperature exhibited strongly compositional dependence. A good linear relation was shown in Tm temperature vs x content and a DPT behavior was found in xPZnTe–(1?x)PZT (x = 0.02‐0.08). The thermal expansion properties showed a low thermal expansion coefficient in the low temperature while a high thermal expansion coefficient in the high temperature. Besides, the thermal expansion curve also showed the characteristic of DPT in PZnTe–PZT ceramics.  相似文献   

15.
Lead‐free 0.955K0.5Na0.5Nb1‐zTazO3‐0.045Bi0.5Na0.5ZrO3+0.4%MnO ceramics (abbreviated as KNNTaz‐0.045BNZ+0.4Mn) were prepared by a conventional solid‐state sintering method in a reducing atmosphere (oxygen partial pressure of 1 × 10?10 atm). All ceramics with a pure perovskite structure show the two‐phase coexistence zone composed of rhombohedral and tetragonal phase. Ta5+ ions substitute for Nb5+ ions on the B‐site, which results in a decrease in the R phase fraction in the two‐phase coexistence zone. The R‐T phase transition temperature moves to room temperature due to the substitution of Nb5+ ions by Ta5+ ions. A complex domain structure composed of small nano‐domains (~70 nm) formed inside large submicron domains (~200 nm) exists in KNNTa0.02‐0.045BNZ+0.4Mn ceramics, which can induce a strong dielectric‐diffused behavior and improve the piezoelectric properties. The temperature stability for the reverse piezoelectric constant for the KNNTaz‐0.045BNZ+0.4Mn ceramics can be improved at = 0.02. Excellent piezoelectric properties (d33 = 328 pC/N, and  = 475 pm/V at Emax = 20 kV/cm) were obtained for the KNNTa0.02‐0.045BNZ+0.4Mn ceramics.  相似文献   

16.
A high‐voltage coefficient has been found in lead‐free piezoelectric particulate composites based on epoxy with lead‐free (K0.50Na0.50)0.94Li0.06NbO3 (KNLN) piezoceramic particles with a natural cubic morphology. The KNLN powder used in the composites has been prepared using a new solid‐state double calcination processing route. These particles were subsequently used to create random and structured KNLN‐epoxy composites. Using dielectrophoresis, these natural cubical KNLN particles were structured into one‐dimensional chains inside the epoxy matrix. Composites produced with these powders showed piezoelectric properties about a factor of 2 higher than those of composites processed with conventionally calcined KNLN powders. The dielectrophoretically structured KNLN‐epoxy composites with optimized particle size and morphology showed excellent piezoelectric properties, which can replace lead containing piezoelectric composites for sensor and energy harvesting applications in future.  相似文献   

17.
The structure and properties of Mn-doped 0.67BiFeO3-0.33BaTiO3 ceramics are systematically investigated with respect to the effects of annealing prior to rapid cooling by quenching in air. Air-quenching induces a change in crystal structure from pseudo-cubic to rhombohedral, with higher quenching temperatures leading to an increased rhombohedral distortion. These structural changes are correlated with the appearance of more well-defined ferroelectric domain configurations. It is shown that the surface preparation procedures for XRD measurements can induce significant changes in the peak profiles, indicating differences in crystal structure between the surface and bulk regions. Frequency dispersion in the temperature-dependent relative permittivity for the as-sintered sample is significantly reduced after quenching, accompanied by enhancement of the Curie point and improved temperature-stability of piezoelectric properties. It is proposed that the formation of defect clusters by A-site cation diffusion during cooling is circumvented by quenching, leading to the observed modification of structural distortion and ferroelectric properties.  相似文献   

18.
Structural analysis of electrically poled samples of polycrystalline, (1‐x)Bi(Mg1/2Zr1/2)O3xPbTiO3 piezoceramics across morphotropic phase boundary reveals electric field‐induced cubic to tetragonal phase transition and significant domain reorientation in tetragonal and two‐phase compositions. The c‐axis domain elongation is observed for tetragonal compositions after poling. The morphotropic phase boundary composition, having coexisting cubic and tetragonal phases in the unpoled state, exhibits alteration in relative proportion of the two phases, in addition to domain extension and reorientation along c‐axis. For the morphotropic phase boundary composition, the tetragonality (c/a) is enhanced with significantly large c‐axis strain (~0.92%) in tetragonal phase after poling. Origin of ferroelectric P‐E loop in cubic compositions is linked with the electric field‐induced phase transition.  相似文献   

19.
In this study lead‐free 2‐2 and 0‐3 ceramic/ceramic composites comprised of the non‐ergodic relaxor 0.93(Bi1/2Na1/2)TiO3–0.07BaTiO3 and ergodic relaxor 0.94Bi0.5(Na0.75K0.25)0.5TiO3–0.06BiAlO3 were investigated. The macroscopic electromechanical behavior was characterized as a function of continuent content, revealing an enhancement in the unipolar strain from the multilayer composite structure. Systematic evaluation of the effects of co‐sintering on microstructural properties, such as grain size and porosity, revealed potential mechanisms by which the increase in unipolar strain was achieved. In addition, interdiffusion between the constituents was observed, providing evidence for the formation of a functionally graded ceramic by co‐sintering. These data are contrasted with high‐resolution energy dispersive X‐ray microanalysis for measurement of chemical composition across the interface of 2‐2 ceramics. These findings provide insight into how synthesis routes can be optimized for tailoring the enhancement of electromechanical properties of lead‐free electroceramic composite systems.  相似文献   

20.
Rhombohedral 0.69Pb(Zr0.47Ti0.53)‐0.31Pb(Zn0.6Ni0.4)NbO3 (PZT‐PZNN) ceramics were textured using 10.0 vol. % BaTiO3 (BT) platelets along the <001> direction at 950°C with a high Lotgering factor of 95.3%. BT platelets did not react with the PZT‐PZNN ceramics, and the textured PZT‐PZNN ceramic had a tetragonal structure. The PZT‐PZNN ceramics exhibited a strain of 0.174% with a piezoelectric strain constant (d*33) of 580 pC/N at 3.0 kV/mm. The textured PZT‐PZNN ceramic showed an increased strain of 0.276% and d*33 of 920 pC/N at 3.0 kV/mm, which can be explained by the domain rotation. However, the d33 values of the textured specimens are smaller than those of the untextured specimens because of the small remanent polarization and relative dielectric constant of BT platelets. The textured PZT‐PZNN ceramic synthesized in this work can be used for piezoelectric multilayer actuators because of its large strain and low sintering temperature.  相似文献   

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