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1.
In this work, we fabricated the (1‐x)BiFeO3xBaTiO3+y‰ mol CuO ceramics by the modified thermal quenching technique. The pure perovskite phase was formed and a morphotropic phase boundary (MPB) was observed in the ceramics with = 0.30‐0.33. The addition of CuO can significantly enhance the density of the BiFeO3‐BaTiO3 material. Importantly, an enhanced piezoelectric constant (d33=165 pC/N), a large electric‐field‐induced strain (?S = 0.54%: peak to peak strain) and a large piezoelectric actuator constant (d33*=449 pm/V) together with a high Curie temperature (TC) of 503°C were observed in the ceramics with = 0.30 and = 5. As a result, the enhanced piezoelectricity and large electric‐field‐induced strain could significantly stimulate further researches in BFO‐based ceramics.  相似文献   

2.
(1 ? x)(0.85Bi0.5Na0.5TiO3–0.11Ba0.5K0.5TiO3–0.04BaTiO3)‐ xK0.5Na0.5NbO3 lead‐free piezoelectric ceramics with = 0.00, 0.02, 0.03, 0.04, 0.05, and 0.10 were prepared by a conventional solid state method. A coexistence of rhombohedral (R) and tetragonal (T) phases was found in the system, which tended to evolve into pseudocubic symmetry when x increases. The = 0.04 sample exhibited improved electrical properties: the dielectric constant εr = 1900 with the low loss tangents 0.06, the Smax/Emax of ~400 and ~460 pm/V under unipolar and bipolar electric field, respectively. Meanwhile, piezoelectric constant d33 still maintained ~160 pC/N. These could be owed to the formation of polar nanoregions for relaxor phase.  相似文献   

3.
A new piezoelectric system of (1−xy)BaTiO3-yCaZrO3-xBaSnO3 (BT-yCZ-xBS) was designed to achieve enhanced piezoelectric/strain properties and temperature stability. First, the relationships between composition, phase, and electrical properties are systematically investigated. The broad phase boundary with successive rhombohedral-orthorhombic (R-O) and orthorhombic-tetragonal (O-T) was obtained in 0.04 ≤  0.05 and 0.04 ≤  0.07 by tailoring the relationship of composition and phase structure, confirmed by X-ray diffraction, temperature-dependent dielectric constants, and Raman spectra. The optimized piezoelectric coefficient of d33 = 560 pC/N, high strain of >0.20%, and large converse piezoelectric coefficient of d33* = 1170 pm/V were realized. Second, the optimized piezoelectricity both demonstrate a stable performance with fluctuation <8% for d33* and 20% for d33 between 22 and 60°C since the broad phase boundary is exhibited in this temperature range. We believe that this work is a successful example to optimize piezoelectric properties and enhance the stability for piezoceramics.  相似文献   

4.
The development of high-temperature lead-free piezoelectric ceramics with excellent electromechanical properties under low field remains a key challenge. A series of 0.995(xBiFeO3-(1-x)BaTiO3)-0.005Bi(Zn0.5Hf0.5)O3 ceramics were designed via modulating phase composition. The excellent electromechanical properties of d33* = 511 pm/V (45 kV/cm) at room temperature and S = 0.476 % (d33* = 1190 pm/V, 40 kV/cm) at 120 ℃ were achieved in the x = 0.67 ceramic owing to the synergistic contribution of phase composition and domain evolution. The XRD results verify that the x = 0.67 ceramic is dominated by the pseudocubic phase. The PFM results in the x = 0.67 and 0.71 ceramics confirm that the domain structures consist of nanodomains with strong and weak piezoelectric responses. More importantly, the temperature and voltage-dependent domain evolution testify the nanodomains are easier to switch in the x = 0.67 ceramic. This work provides a strategy to optimize the electromechanical performance at the low field and a deeper understanding of BF-BT-based piezoceramics.  相似文献   

5.
In this work, we report a lead‐free piezoelectric ceramic of (0.9‐x)NaNbO3‐0.1BaTiO3xBaZrO3, and the effects of BaZrO3 on the phase structure, microstructure, electrical properties and temperature stability are investigated. A morphotropic phase boundary‐like region consisting of rhombohedral (R) and tetragonal (T) phases is constructed in the compositions with = 0.035‐0.04. More importantly, in situ temperature independence of the piezoelectric effect {piezoelectric constant (d33) and strain} can be achieved below the Curie temperature (Tc). Intriguingly, the electric field‐induced strain is still observed at ≥ Tc due to the combined actions of the electrostrictive effect and the electric field‐induced phase transition. We believe that NaNbO3‐based ceramics of this type have potential for applications in actuators and sensors.  相似文献   

6.
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   

7.
《Ceramics International》2017,43(11):8004-8009
In this study, <001>-textured 0.99(K0.5Na0.5)0.95Li0.05Nb0.93Sb0.07O3−0.01CaZrO3 [abbreviated as 0.99KNLNS-0.01CZ] lead-free ceramics were prepared by templated grain growth (TGG) using plate-like NaNbO3 templates and sintered by a two-step sintering process with different soaking time. All textured samples with high Lotgering factor (f >85%) presented orthorhombic and tetragonal coexisting phase, and the proportion of orthorhombic phase was varied with prolonged soaking time. A large piezoelectric constant d33 (~ 310 pC/N) was obtained in the textured samples with a 12 h soaking time, which was almost twice larger compared to the randomly oriented one. Furthermore, the field-induced piezoelectric strain coefficient d33*(~ 440 pm/V) of the textured ceramics with 6 h soaking time was larger than the value of randomly oriented one (~ 298 pm/V) at room-temperature. Enhanced piezoelectric response and good temperature stability prove that <001>-textured 0.99KNLNS-0.01CZ ceramics are promising candidates in the field of lead-free piezoelectric materials.  相似文献   

8.
New binary system (1?x) PbTiO3?xBi(Ni1/2Zr1/2)O3 (PT–100x BNZ) with ≤ 0.45 were synthesized via solid‐state reaction route. A morphotropic phase boundary (MPB) was identified around x = 0.40 by X‐ray diffraction (XRD) method. The ceramics with MPB composition exhibit enhanced ferroelectric properties. A large piezoelectric coefficient (d33) up to 400 pC/N was obtained for the PT–40BNZ, which is comparable with the PbTiO3–BiScO3 (PT–BS, 450 pC/N).The frequency dependence of dielectric permittivity of PT–40BNZ shows characteristic of a strong relaxor feature and a transition temperature around 290°C (1 MHz). Temperature effect on the unipolar strain was also investigated. The present system with high d33 is a competitive piezoelectric material, as no expensive oxide is used here compared with the PT–BS.  相似文献   

9.
New lead‐free perovskite solid solution ceramics of (1 ? x)(Bi1/2Na1/2)TiO3xBa(Ni1/2Nb1/2)O3[(1?x)BNT–xBNN,= 0.02–0.06) were prepared and their dielectric, ferroelectric, piezoelectric, and electromechanical properties were investigated as a function of the BNN content. The X‐ray diffraction results indicated that the addition of BNN has induced a morphotropic phase transformation from rhombohedral to pseudocubic symmetry approximately at = 0.045, accompanying an evolution of dielectric relaxor behavior as characterized by enhanced dielectric diffuseness and frequency dispersion. In the proximity of the ferroelectric rhombohedral and pseudocubic phase coexistence zone, the = 0.045 ceramics exhibited optimal piezoelectric and electromechanical coupling properties of d33~121 pC/N and kp~0.27 owing to decreased energy barriers for polarization switching. However, further addition of BNN could cause a decrease in freezing temperatures of polar nanoregions till the coexistence of nonergodic and ergodic relaxor phases occurred near room temperature, especially for the = 0.05 sample which has negligible negative strains and thus show the maximum electrostrain of 0.3% under an external electric field of 7 kV/mm, but almost vanished piezoelectric properties. This was attributed to the fact that the induced long‐range ferroelectric order could reversibly switch back to its original ergodic state upon removal of external electric fields.  相似文献   

10.
The properties of relaxor ceramics in the compositional series (1?x)K0.5Bi0.5TiO3xBa(Ti0.8Zr0.2)O3 have been investigated. Values of Tm, the temperature of maximum relative permittivity, decreased from 380°C at = 0.0 to below room temperature for > 0.7. Compositions = 0.1 and 0.2 were piezoelectric and ferroelectric. The maximum value of d33 piezoelectric charge coefficient, 130 pC/N, and strain, 0.14%, occurred at = 0.1. Piezoelectric properties of = 0.1 were retained after thermal cycling from room temperature to 220°C, consistent with results from high‐temperature X‐ray diffraction indicating a transition to single‐phase cubic at ~300°C.  相似文献   

11.
Pb (In1/2Nb1/2) O3‐Pb (Sc1/2Nb1/2) O3‐PbTiO3 (PIN‐PSN‐PT) ternary ceramics with compositions near morphotropic phase boundary (MPB) were fabricated by solid‐state‐sintering process. Dielectric and piezoelectric properties of xPIN‐yPSN‐zPT (x = 0.19, 0.23 and z = 0.365, 0.385) ceramics were investigated as a function of temperature, showing high Tr‐t and Tc on the order of 160 ~ 200°C and 280 ~ 290°C, respectively. The xPIN‐yPSN‐0.365PT (x = 0.19 and 0.23) ceramics do not depolarize at the temperature up to 200°C, showing a better thermal stability when compared to the state‐of‐the‐art relaxor‐PbTiO3 systems. A slight variation (<9%) of kp, kt, and k33 was observed in the temperature range of 25°C‐160°C for xPIN‐yPSN‐0.385PT (x = 0.19 and 0.23) ceramics. Rayleigh analysis was employed to quantify the contribution of domain wall motion to piezoelectric response, where the domain wall contribution was found to increase with composition approaching MPB for PIN‐PSN‐PT system.  相似文献   

12.
Lead-free ferroelectric ceramics with high tailored strong-electric-field electrical properties (energy storage, electrocaloric cooling, and energy harvesting, etc.) are attractive to many fields, such as modern electronics, medical and military, etc. We demonstrated that the strong-electric-field electrical properties of the 0.89(Bi0.5Na0.5TiO3)-0.11(BaTiO3) (BNT-BT) relaxor ceramics not only could be tailored easily after doping the (BaTiO3)0.5-(BiMg0.5Ti0.5O3)0.5 (BT-BMT, the functional-group), but also could be improved largely. As a result, an optimized electrostrain (S ~ 0.4%) was acquired at x = 0.12, and an optimized energy storage density (W ~ 0.775 J/cm3) with a high efficiency (η ~ 50%) was achieved at x = 0.24, as well as a phase-induced negative electrocaloric (EC) effect (ΔT ~ 3.72 K) was harvested at x = 0.04. It is concluded that the functional-group-doping can be regarded as a new strategy to tailor and improve the strong-electric-field electrical properties of ferroelectric materials.  相似文献   

13.
(1?x)Pb(Hf1?yTiy)O3xPb(Yb0.5Nb0.5)O3 (= 0.10–0.44, = 0.55–0.80) ceramics were fabricated. The morphotropic phase boundary (MPB) of the ternary system was determined by X‐ray powder diffraction. The optimum dielectric and piezoelectric properties were achieved in 0.8Pb(Hf0.4Ti0.6)O3–0.2Pb(Yb0.5Nb0.5)O3 ceramics with MPB composition, where the dielectric permittivity εr, piezoelectric coefficient d33, planar electromechanical coupling kp, and Curie temperature Tc were found to be on the order of 1930,480 pC/N, 62%, and 360°C, respectively. The unipolar strain behavior was evaluated as a function of applied electric field up to 50 kV/cm to investigate the strain nonlinearity and domain wall motion under large drive field, where the high field piezoelectric d33* was found to be 620 pm/V for 0.82Pb(Hf0.4Ti0.6)O3–0.18Pb(Yb0.5Nb0.5)O3. In addition, Rayleigh analysis was carried out to study the extrinsic contribution, where the value was found to be in the range 2%–18%.  相似文献   

14.
The crystal structure, electromechanical properties, and electrocaloric effect (ECE) in novel lead‐free (Bi0.5K0.5)TiO3‐La(Mg0.5Ti0.5)O3 ceramics were investigated. A morphotropic phase boundary (MPB) between the tetragonal and pseudocubic phase was found at x = 0.01‐0.02. In addition, the relaxor properties were enhanced with increasing the La(Mg0.5Ti0.5)O3 content. In situ high‐temperature X‐ray diffraction patterns and Raman spectra were characterized to elucidate the phase transition behavior. The enhanced ECE (ΔT = 1.19 K) and piezoelectric coefficient (d33 = 103 pC/N) were obtained for x = 0.01 at room temperature. Meanwhile, the temperature stability of the ECE was considered to be related to the high depolarization temperature and relaxor characteristics of the Bi0.5K0.5TiO3‐based ceramics. The above results suggest that the piezoelectric and ECE properties can be simultaneously enhanced by establishing an MPB. These results also demonstrate the great potential of the studied systems for solid‐state cooling applications and piezoelectric‐based devices.  相似文献   

15.
Perovskite‐type xBi(Mg1/2Ti1/2)O3–(0.56 ? x)PbZrO3–0.44PbTiO3 (xBMT–PZ–PT) ternary solid solution ceramics were synthesized via a conventional solid‐state reaction method. The phase transition behaviors, dielectric, ferroelectric, and piezoelectric properties were investigated as a function of the BMT content. The X‐ray diffraction analysis showed that the tetragonality of xBMT–PZ–PT was enhanced with increasing the BMT content, and a morphotropic phase boundary (MPB) between rhombohedral and tetragonal phases was identified approximately in the composition of = 0.08. In addition, the dielectric diffuseness and frequency dispersion behavior were induced with the addition of BMT and a normal‐relaxor‐diffuse ferroelectric transformation was observed from the PZ‐rich side to the BMT‐rich side. The electrical properties of xBMT–PZ–PT ceramics exhibit obviously compositional dependence. The = 0.08 composition not only possessed the optimum properties with εT33/ε0 = 1450, Qm = 69, d33 = 390 pC/N, kp = 0.46, Pr = 30 μC/cm2, Ec = 1.4 kV/mm, Tc = 325°C, and a strain of 0.174% (d33* = 436 pm/V) under an electric field of 4 kV/mm as a result of the coexistence of two ferroelectric phases near the MPB, but also owned a good thermal‐depolarization behavior with a d33 value of >315 pC/N up to 290°C and a frequency‐insensitive strain behavior.  相似文献   

16.
《Ceramics International》2023,49(2):1820-1825
Due to the high Curie temperature (TC), BiFeO3–BaTiO3 (BF-BT) ceramics have been broadly investigated in high-temperature piezoelectric devices. The piezoelectric constant is one of the most significant factors in determining the sensitivity and reliability of piezoelectric functional components. However, the poor piezoelectric constant (d33) of BF-BT ceramic has prevented the practical application of the material. In this work, we innovatively introduce the 0.93Bi0.5Na0.5TiO3-0.07BaTiO3 (0.93NBT-0.07BT) component to 0.7BF-0.3BT ceramic, to build a morphotropic phase boundary (MPB) for enhancing d33. The XRD analysis shows that the (0.7BF-0.3BT)-x(0.93NBT-0.07BT) ceramics are still in the MPB region with R–PC phases coexistence, and exhibits a homogeneous solid solution. Moreover, the introduction of 0.93NBT-0.07BT ceramic suppresses the generation of defects and facilitates grain growth, thus enhancing piezoelectric property. In consequence, an optimum piezoelectricity d33 = 213 pC/N along with Tc~450 °C was obtained in (0.7BF-0.3BT)-0.01(0.93NBT-0.07BT). This research provides a new idea for the application of BF-BT ceramics in high-temperature piezoelectric devices.  相似文献   

17.
The 0.72Bi(Fe1?xAlx)O3–0.28BaTiO3 (= 0, 0.01, 0.03, 0.05, and 0.07, abbreviated as BFAx–BT) lead‐free high‐temperature ceramics were prepared by the conventional ceramic processing. Systematic investigation on the microstructures, crystalline structures, dielectric and piezoelectric properties, and high‐temperature stability of piezoelectric properties was carried out. The crystalline structures of BFAx–BT ceramics evolve from rhombohedral structure with x < 0.01 to the coexistence of rhombohedral structure and pseudocubic phases with ≈ 0.01, finally to pseudocubic phases when x > 0.03. Remarkably high‐temperature stability with near‐zero temperature coefficient of piezoelectric properties (TCkp), together with improved piezoelectric properties has been achieved for = 0.01 BFAx–BT ceramics. The BFAx–BT(= 0.01) ceramics simultaneously show the excellent piezoelectric properties of d33 = 151 pC/N, kp = 0.31 and super‐high‐temperature stability of Td = 420°C, TCkp = 1 × 10?4. It is considered that the observed strong piezoelectricity and remarkably high‐temperature stability should be ascribed to the phase coexistence of rhombohedral and pseudocubic phases. The rhombohedral phases have a positive TCkp value and the pseudocubic phases possess a negative TCkp value. Thus, the TCkp value of BFAx–BT ceramics can be tuned by composition of x.  相似文献   

18.
SrTiO3-modified lead-free piezoelectric ceramics, (0.93-x)Bi0.5Na0.5TiO3-xSrTiO3-0.06BaTiO3-0.01 K0.5Na0.5NbO3 [(BNT-xST)-BT-KNN, x = 0-0.06], were prepared using a conventional solid-state reaction method. The XRD structure analysis and electric properties characteristics revealed the ST-induced phase transformation from the ferroelectric phase to the relaxor phase and their coexistence state. Benefiting from the ST-destructed ferroelectric long-range orders, the high normalized strain value of 600 pm/V was obtained in the (BNT-0.02ST)-BT-KNN ceramic at 5 kV/mm. The ST-generated relaxor phase was found to have a constructive effect on improving the temperature stability and restraining the hysteresis of the electric-field-induced strain. The normalized strain of (BNT-0.06ST)-BT-KNN ceramics could be kept at a high value ~337 pm/V at elevated temperature up to 120°C.  相似文献   

19.
《Ceramics International》2022,48(18):25880-25893
Flexible composites containing BaTiO3 nanoparticles into Gelatin bio-polymer matrix were designed and investigated. Following the idea that the electric field concentration in corners/edges at the interfaces between dissimilar materials give rise to enhanced effective permittivity in composites, cuboid-like BaTiO3 nanoparticles have been employed as nanofillers into Gelatin matrix by using an inexpensive solution-based processing method. As predicted by finite element method simulations developed for cubic-like inclusions into a homogeneous polymer matrix, the experimental permittivity of xBT-(1-x)Gelatin composites increases when increasing the high-permittivity filler addition. For the composition x = 40 wt% (corresponding to 12 vol% BaTiO3 addition), permittivity reaches εr ~15.7 with respect to εr ~9.8 of pure Gelatine (measured at 105 Hz), while the average piezoelectric coefficient d33 as determined by piezoelectric force microscopy shows a remarkable increase up to 21 pm/V in composites with x = 40 wt%, in comparison to ~7 pm/V in pure Gelatin. By using the experimentally determined material constants, the simulated piezoelectric voltage output vs. time has shown a similar increase (about a doubling of its amplitude) of the harvesting signal in the composite with x = 40 wt% BT, with respect to one of the polymer matrix, thus demonstrating the beneficial role of embedding BT nanoparticles into the biopolymer for increasing the mechanical harvesting response.  相似文献   

20.
Na1/2Bi1/2TiO3 (NBT)-based materials are promising lead-free alternatives due to their large electrostrain and stable mechanical quality factor. Nonetheless, the relatively low depolarization temperature (Td) impairs its practical application. Recently, quenching from sintering temperature was adopted to increase Td of NBT-based ceramics. However, the origin of the quenching-induced increase in Td is still debated. In this study, quenching effects in (1-x)(0.4Na1/2Bi1/2TiO3-0.6BiFeO3)-xBaTiO3 ceramics are investigated. With increasing BaTiO3 content, this system transforms from ferroelectric to relaxor state at room temperature, with a criticality at x = 0.07, which exhibits R3c and P4bm coexisted phases. Ferroelectric and relaxor compositions exhibit different responses upon quenching. Upon quenching the ferroelectrics, Td increases from 420 to 580 °C for x = 0.04, but d33 is majorly unaltered. However, upon quenching the relaxors, Td increases marginally, while d33 increases from 62 to 97 pC/N. The correlation between the structural evolution and electrical responses upon quenching ferroelectric and relaxor compositions is explored.  相似文献   

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