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1.
通过传统固相合成工艺制备了(K0.465+xNa0.465+yLi0.07)(Nb0.95-zSb0.05)O3(x,y,z=-0.01~0.02)无铅压电陶瓷,研究了非化学计量比对陶瓷结构及压电性能的影响。结果表明符合化学计量比的陶瓷具有四方钙钛矿结构;在实验范围内,K和Nb的过量或少量均不会改变体系的相结构,而Na过量将会导致体系正交-四方相变温度升高到室温以上,并且正交-四方相变温度随y的增加而升高;过量添加约0.5%(摩尔分数)的K或Na便能补偿在高温烧结时的碱金属元素的挥发损失,进而提高陶瓷的压电性能;该体系陶瓷的组分在较大范围内变化时(如当y=z=0时,x=0~0.02;当x=z=0时,y=0~0.01;以及当x=y=0时,z=-0.01~0.005),仍然能保持d33>200pC/N和kP>40%这样较好的性能。上述结果不仅有利于在研究中材料制备工艺的重复,而且有利于当材料在器件应用时所面临的规模化生产。 相似文献
2.
(1--x )(K0.475Na0.475Li0.05)(Nb0.8Ta0.2)O3--x BiCoO3 (KNLNT--BC) lead-free piezoelectric ceramics were prepared by the conventional solid-state sintering method. Effects of the BC content on the phase structure, microstructure and electrical properties of KNLNT--BC ceramics were investigated. XRD patterns reveal that all the ceramic samples are in the pure perovskite-type structure, and the phase structure changes from the tetragonal to pseudo-cubic phase with the increase of the BC content. After the substitution of BC, the grain size is significantly reduced and relaxer behaviors are induced. By adding a small amount of BC to KNLNT ceramics, piezoelectric properties are improved, while further addition of BC makes the piezoelectric properties deteriorate markedly. The optimized electrical properties at x = 0.005 are as follows: d 33 = 194 pC/N, k p = 0.44. 相似文献
3.
(1 − x) (K0.44Na0.52Li0.04)(Nb0.84Ta0.1Sb0.06)O3 − x BiFeO3 (x = 0, 0.002, 0.004, 0.006, 0.008, 0.01) lead-free piezoelectric ceramics were prepared by the conventional ceramic processing. The compositional dependence of the phase structure and the electrical properties of the ceramics were studied. A morphotropic phase boundary between the orthorhombic and tetragonal phases was identified in the composition range of 0.004 < x < 0.006. The ceramics near the morphotropic phase boundary exhibit a strong compositional dependence and enhanced piezoelectric properties. The ceramics with 0.6 mol.% BiFeO3 exhibit good electrical properties (d33 ∼ 246 pC/N, kp ∼ 43%, Tc ∼ 285 °C, ?r ∼ 1871, and tan δ ∼ 1.96%). These results show that the (1 − x) (K0.44Na0.52Li0.04)(Nb0.84Ta0.1Sb0.06)O3 − x BiFeO3 ceramic is a promising lead-free piezoelectric material for applications in different devices. 相似文献
4.
Lead-free piezoelectric ceramics (1 − x)(K0.5Na0.5)NbO3-xLiNbO3 have been synthesized by traditional ceramics process without cold-isostatic pressing. The effect of the content of LiNbO3 and the sintering temperature on the phase structure, the microstructure and piezoelectric properties of (1 − x)(K0.5Na0.5)NbO3-xLiNbO3 ceramics were investigated. The result shows that the phase structure transforms from the orthorhombic phase to tetragonal phase with the increase of the content of LiNbO3, and the orthorhombic and tetragonal phase co-exist in (K0.5Na0.5)NbO3-LiNbO3 ceramics when the content of LiNbO3 is about 0.06 mol. The sintering temperature of (1 − x)(K0.5Na0.5)NbO3-xLiNbO3 decreases with the increase of the content of LiNbO3. The optimum composition for (1 − x)(K0.5Na0.5)NbO3-xLiNbO3 ceramics is 0.94(K0.5Na0.5)NbO3-0.06LiNbO3. The optimum sintering temperature of 0.94(K0.5Na0.5)NbO3-0.06LiNbO3 ceramics is 1080 °C. Piezoelectric properties of 0.94 (K0.5Na0.5)NbO3-0.06LiNbO3 ceramics under the optimum sintering temperature are piezoelectric constant d33 of 215 pC/N, planar electromechanical coupling factor kp of 0.41, thickness electromechanical coupling factor kt of 0.48, the mechanical quality factor Qm of 80, the dielectric constant of 530 and the Curie temperature Tc = 450 °C, respectively. The results indicate that 0.94(K0.5Na0.5)NbO3-0.06LiNbO3 piezoelectric ceramics is a promising candidate for lead-free piezoelectric ceramics. 相似文献
5.
Lead-free ceramics (K0.5Na0.5)(Nb0.9Ta0.1)O3 (KNNT) + x mol% K4CuNb8O23 (KCN) + y mol% MnO2 have been prepared using the conventional solid-state reaction technique. Crystalline structures and Microstructures were analyzed by X-ray diffraction and scanning electron microscope (SEM) at room temperature. The low dielectric loss tanδ and relatively high piezoelectric properties were obtained when KCN and MnO2 were added into KNNT ceramics. The ceramics with x = 1.0, y = 0.50 exhibited excellent piezoelectric properties: high mechanical quality factor Qm = 1563, piezoelectric coefficient d33 = 96pC/N, electromechanical coupling coefficient kp = 42.2%, kt = 44.5%, k33 = 58.4%, relative dielectric constant ε′ = 308, tanδ = 0.4%. This material is a promising candidate for the lead-free piezoelectric transformer applications. 相似文献
6.
Jigong Hao Zhijun Xu Ruiqing Chu Yanjie Zhang Qian Chen Guorong Li Qingrui Yin 《Journal of Materials Science》2009,44(22):6162-6166
To improve both the temperature stability and the mechanical quality factor of (K0.5Na0.5)0.94Li0.06NbO3 (KNLN6) ceramics, dense (K4CuNb8O23, Bi2O3)-modified KNLN6 lead-free ceramics were prepared. Results showed that the (K4CuNb8O23, Bi2O3)-modified ceramics exhibited a flat, temperature-stable behavior over the range of 20–120 °C. K4CuNb8O23 (KCN) and Bi2O3-codoping changed the KNLN6 to “hard” ceramics with a significant improvement of mechanical quality factor, Q
m, from 82 to 756. Meanwhile, the piezoelectric constant, d
33, and the planar electromechanical coefficient, k
p, still maintained relatively high levels (d
33 ~118 pC/N, k
p ~35.6%). These results indicate that the modified KNLN6 ceramics are promising lead-free piezoelectric candidates for practical
applications. 相似文献
7.
Juan Du Zhijun Xu Ruiqing Chu Xiujie Yi Wenna Chao Xiaofeng Zhang Peiyu Zhang Limei Zheng 《Materials Science and Engineering: B》2013,178(16):1027-1031
Lead-free ceramics (1 − x)(K0.5Na0.5)0.95Li0.05Sb0.05Nb0.95O3-xSmAlO3 (KNLNS-xSA) were prepared by conventional sintering technique. The phase structure, dielectric and piezoelectric properties of the ceramics were investigated. All compositions show a main perovskite structure, exhibiting room-temperature symmetries of tetragonal at x ≤ 0.0075, of pseudo-cubic at x = 0.0100. The Curie temperature of KNLNS-xSA ceramics decreases with increasing SmAlO3 content. Moreover, the addition of SmAlO3 can effectively broaden the sintering temperature range of the ceramics. The KNLNS-xSA ceramic with x = 0.0050 has an excellent electrical behavior of piezoelectric coefficient d33 = 226 pC/N, planar mode electromechanical coupling coefficient kp = 38%, dielectric loss tan δ = 3.0%, mechanical quality factor Qm = 60, and Curie temperature TC = 327 °C, suggesting that this material could be a promising lead-free piezoelectric candidate for piezoelectric applications. 相似文献
8.
Lead-free (K0.5−x/2Na0.5−x/2Lix)(Nb0.8Ta0.2)O3 (KNLNT) and (K0.49−x/2Na0.49−x/2- LixCa0.01)(Nb0.8Ta0.2)O3 (KNLNT-Ca) ceramics were prepared by a conventional ceramic processing. Structural analysis shows that the Ca2+ doping takes the A site of ABO3 perovskite and decreases the phase transition temperature. Property measurements reveal that as a donor dopant, the Ca2+ doping results in higher room-temperature dielectric constant, lower dielectric loss, and lower mechanical quality factor. In addition, the Ca2+ doping does not change the positive piezoelectric coefficient d33, but increases the converse piezoelectric coefficient d33* significantly. This is likely due to the increase in the relaxation, as well as the appearance of (CaNa/K•--VNa/K′) defect dipoles. 相似文献
9.
Y.G. Lv C.L. Wang J.L. Zhang L. Wu M.L. Zhao J.P. Xu 《Materials Research Bulletin》2009,44(2):284-287
Lead-free (K0.5Na0.5)(Nb1−xTax)O3 ceramics with x = 0.00-0.30 were prepared by the solid-state reaction technique. The effects of Ta on microstructure, crystallographic structure, phase transition and piezoelectric properties have been investigated. It has been shown that the substitution of Ta decreases Curie temperature TC and orthorhombic-tetragonal phase transition temperature TO-T, while increasing the rhombohedral-orthorhombic phase transition temperature TR-O. In addition, piezoelectric activity is enhanced with the increase of Ta content. The ceramics with x = 0.30 have the high value of piezoelectric coefficient d33 = 205 pC/N. Moreover, kp shows little temperature dependence between −75° C and 75 °C, and d33 exhibits very good thermal stability over the range from −196 °C to 75 °C in the aging test. 相似文献
10.
Wei LiZhijun Xu Ruiqing ChuPeng Fu Guozhong Zang 《Materials Science and Engineering: B》2011,176(1):65-67
Lead-free (Ba0.93Ca0.07)(Ti0.95Zr0.05)O3 (BCZT) ceramics were prepared using a solid-state reaction technique. The structure and electrical properties were investigated with a special emphasis on the influence of sintering temperature. Crystalline structures and microstructures were analyzed by X-ray diffraction and scanning electron microscope (SEM) at room temperature. The BCZT ceramics sintered at 1450 °C show the highest densification and exhibit excellent piezoelectric properties of high piezoelectric coefficient d33 = 387 pC/N, planar mode electromechanical coupling coefficient kp = 44.2%, mechanical quality factor Qm = 140 and Curie temperature Tc = 108 °C. 相似文献
11.
Effects of Cu doping on the ferroelectric and piezoelectric properties of 0.0038 mol K5.4Cu1.3Ta10O29 modified (K0.5Na0.5)NbO3 ceramics have been investigated. On the basis of analyses on crystal structure and polarization hysteresis, it is suggested that Cu ions reveal amphoteric doping behavior in KNN ceramics. At doping levels up to 1 mol%, the Cu ions substitute pentavalent B-site cations, acting as acceptors that generate O-vacancies to resultantly harden the ceramics. At doping levels above 1.5 mol%, however, Cu ions play a role as donors by replacing monovalent A-site cations. A specimen doped with 0.5 mol% CuO shows an extremely high mechanical quality factor of 3053, which is higher than those of any other reports on KNN-based ceramics. 相似文献
12.
(K0.5Na0.5)NbO3 (KNN) and 0.995(K0.5Na0.5)NbO3-0.005AETiO3 (AE = Mg, Ca, Sr, Ba) were successfully prepared by conventional ceramic processing and without the cold-isostatic-pressing (CIP) process. The effects of low AETiO3 (AET) concentration on crystal structure, density, dielectric and piezoelectric properties of the KNN based ceramics were evaluated. The results show that adding MgTiO3(MT) and BaTiO3(BT) to KNN can lead to the appearance of a trace amount of second phase(s), reduced density and deteriorated electrical properties. Adding CaTiO3(CT) and SrTiO3(ST) to KNN can promote densification and optimize electrical properties. Two phase transitions at Tt-o ( the temperature at which the phase transition from orthorhombic to tetragonal occurs) and Tc (the Curie temperature) were observed in KNN and all KNN-AET ceramics, by using differential scanning calorimetry (DSC) analysis and dielectric characterization. Adding AET to KNN caused the variations of Tt-o and Tc. 相似文献
13.
Lead-free K0.48Na0.52NbO3 (KNN) ferroelectric thin films were prepared using the radio-frequency magnetron sputtering method. The crystallized KNN phase was confirmed using X-ray diffraction. The KNN thin film exhibited a well-saturated ferroelectric polarization-electric field hysteresis loop with high remanent polarization. The dielectric and electrical properties of the KNN thin film were investigated over a wide range of frequencies from 10 Hz to 1 MHz, and over a wide range of temperatures from 25 °C to 500 °C. The complex impedance relaxations are shown in an impedance Cole-Cole plot. With increasing temperature, the AC conductivity increased, which obeys the power law, σ(ω) = σ0 + Aωs. The activation energy for the conduction process is calculated to be 0.57 eV from the slope of the AC conductivity at the low frequency. 相似文献
14.
Jing LiuJiliang Zhu Xuhai LiMingsong Wang Xiaohong ZhuJianguo Zhu Dingquan Xiao 《Materials Letters》2011,65(6):948-950
CuO-doped 0.98K0.5Na0.5NbO3-0.02BiScO3 (0.98KNN-0.02BS-xCu) lead-free piezoelectric ceramics have been fabricated by ordinary sintering technique. The effects of CuO doping on the dielectric, piezoelectric, and ferroelectric properties of the ceramics were mainly investigated. X-ray diffraction reveals that the samples at doping levels of x ≤ 0.01 possess a pure tetragonal perovskite structure. The specimen doped with 1 mol% CuO exhibits enhanced electrical properties (d33 ~ 207 pC/N, kp ~ 0.421, and kt = 0.424) and relatively high mechanical quality factor (Qm = 288). These results indicate that the 0.98KNN-0.02BS-0.01Cu ceramic is a promising candidate for lead-free piezoelectric ceramics for applications such as piezoelectric actuators, harmonic oscillator and so on. 相似文献
15.
Cheol-Woo Ahn Makarand Karmarkar Dong-Heon Kang Shashank Priya 《Materials Letters》2008,62(20):3594-3596
In this letter we report the effect of CuO and MnO2 additives on the sintering behavior of 0.95(Na0.5K0.5)NbO3-0.05BaTiO3 ceramics. It was found that the composition corresponding to 0.95(Na0.5K0.5)NbO3-0.05BaTiO3 + 2.0 mol% CuO + 0.5 mol% MnO2, sintered at 950 °C for 10 h, exhibited excellent piezoelectric properties corresponding to: kp = 0.41, d33 = 248 pC/N, Qm = 305, ε3T/ε0 = 1258, and Tc = 280 °C. These results indicate the prominence of this composition in lead-free systems. 相似文献
16.
The sintering behavior and dielectric properties for perovskite Ag(Nb0.8Ta0.2)O3 ceramic with Sb2O5 doping was explored. A small amount of Sb2O5 (2.5 wt.%) led to high densification at temperatures < 1060 °C. The dielectric constant increased and the temperature coefficient decreased with increasing concentration of Sb2O5, and the dielectric constant reached 673, combined with a low temperature coefficient of 147 ppm/°C, and dielectric loss of 0.0044 (at 1 MHz) for the sample with 3.5 wt.% Sb2O5 sintered at 1080 °C. 相似文献
17.
LiSbO3 doped and undoped 0.995 K0.5Na0.5NbO3-0.005BiFeO3 piezoelectric ceramics with high properties have been fabricated in air by the conventional ceramic processing. By adding LiSbO3 to K0.5Na0.5NbO3-BiFeO3 ceramics, the dielectric and piezoelectric properties evidently increase. The doped ceramics exhibit good electrical properties. The enhanced piezoelectric properties of the ceramics should be attributed to optimum LiSbO3 substitution and better microstructure with high density. Results show that LiSbO3 doped K0.5Na0.5NbO3-BiFeO3 lead-free piezoelectric ceramics are a promising lead-free piezoelectric material for applications in different devices. 相似文献
18.
Y2O3 doped lead-free piezoelectric ceramics (Bi0.5Na0.5)0.94Ba0.06TiO3 (0-0.7 wt%) were synthesized by the conventional solid state reaction method, and the effect of Y2O3 addition on the structure and electrical properties was investigated. X-ray diffraction shows that Y2O3 diffuses into the lattice of (Bi0.5Na0.5)0.94Ba0.06TiO3 to form a solid solution with a pure perovskite structure. The temperature dependence of dielectric constant of Y2O3 doped samples under various frequencies indicates obvious relaxor characteristics different from typical relaxor ferroelectric and the mechanism of the relaxor behavior was discussed. The optimum piezoelectric properties of piezoelectric constant d33 = 137 pC/N and the electromechanical coupling factor kp = 0.30 are obtained at 0.5% and 0.1% Y2O3 addition, respectively. 相似文献
19.
M. N. Palatnikov V. A. Sandler V. V. Efremov N. V. Sidorov V. T. Kalinnikov 《Inorganic Materials》2011,47(11):1242-1248
The dielectric properties and electrical conductivity of the ferroelectric perovskite solid solutions Li0.07Na0.93Ta0.1Nb0.9O3 and Li0.07Na0.93Ta0.111Nb0.889O3 have been studied at temperatures from 290 to 700 K and frequencies from 25 Hz to 1 MHz. In this temperature range, the solid
solutions undergo a first-order ferroelectric phase transition. Li0.07Na0.93Ta0.111Nb0.889O3 (prepared from coprecipitated Ta2y
Nb2(1 − y)O5 pentoxides) has a markedly lower Curie temperature (by ∼75 K) and higher ionic conductivity and high-frequency dielectric
permittivity in comparison with Li0.07Na0.93Ta0.1Nb0.9O3 (prepared from a mechanical mixture of Ta2O5 and Nb2O5). 相似文献
20.
Tai-Kwang Park 《Materials Research Bulletin》2008,43(3):730-734
Ceramic powders of (Ba,Pb)Pb(Mg1/3Ta2/3)O3 were prepared via a B-site precursor route. Crystal symmetries and lattice parameters were determined. Monophasic perovskite was developed after the two-step reaction process, in which the lattice parameters showed linear changes in the entire composition range. Dielectric responses of the ceramics with compositional and frequency changes were investigated. The results were also compared with the (Ba,Pb)(Zn1/3Ta2/3)O3 data. 相似文献