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1.
Tao Chen Hongli Wang Ting Zhang Guangchang Wang Jifang Zhou Jianwei Zhang Yuhong Liu 《Ceramics International》2014
Effects of sintering temperature on the microstructure and electrical properties of (K0.40Na0.60)0.94Li0.06Nb0.94SbO3 (KNLNS) lead-free ceramics are investigated. The grain size gradually becomes larger with increasing sintering temperature from 1055 °C to 1105 °C, and the piezoelectric property could be enhanced by optimizing their sintering temperature. The ceramic sintered at 1075 °C has optimum electrical properties, i.e., d33~272 pC/N, kp~43.5%, εr~1152, tan δ~0.026, and TC~346 °C. These results show that the sintering temperature can optimize electrical properties of KNLNS ceramics. 相似文献
2.
Grain size control of lead-free Li0.06(Na0.5K0.5)0.94NbO3 piezoelectric ceramics by Ba and Ti doping
Ken-ichi Kakimoto Kiyotaka Ando Hitoshi Ohsato 《Journal of the European Ceramic Society》2010,30(2):295-299
In this study, Ba- and Ti-doped Li0.06(Na0.5K0.5)0.94NbO3 [(1 ? x)Li0.06(Na0.5K0.5)0.94NbO3–xBaTiO3 (x = 0–0.07)] ceramics were prepared by using conventional solid state reaction method, and the microstructure and electric properties of these samples were investigated. The grain size distribution of non-doped Li0.06(Na0.5K0.5)0.94NbO3 ceramics was relatively wide. The microstructure was composed of grains ranging 1.1–5.0 μm in size. However, with increasing Ba and Ti content, the grain size distribution became narrow and the average grain size decreased from 2.0 to 0.9 μm in size. In particular, the microstructure of x = 0.07 sample was composed of grains ranging 0.5–2.2 μm in size. As a result, the frequency dispersion of dielectric constant for the (1 ? x)Li0.06(Na0.5K0.5)0.94NbO3–xBaTiO3 (x = 0–0.07) ceramics was reduced and the mechanical quality factor Qm was enhanced with increasing Ba and Ti content. 相似文献
3.
(1?x)Na0.47K0.47Li0.06NbO3 (NKLN)–xAgSbO3 lead-free piezoelectric ceramics were prepared using a reaction sintering method. The effects of AgSbO3 doping on the structural and electrical properties of NKLN ceramics sintered at 1000–1040 °C were studied. The dopant affected densification, phase content, sintering temperature, microstructure and electrical properties. Variations in the relative intensity of X-ray diffraction peaks were consistent with Ag+ and Sb5+ ions substituting on the perovskite lattice to produce a change in the proportions of co-existing tetragonal and orthorhombic phases. Grain growth during secondary re-crystallization was also affected. The temperature of the orthorhombic–tetragonal (O–T) phase transition and the Curie temperature (TC) decreased as a result of AgSbO3 modifications. The dielectric and piezoelectric properties are enhanced for the composition near the orthorhombic–tetragonal polymorphotropic phase boundary. The 0.92Na0.47K0.47Li0.06NbO3–0.08AgSbO3 ceramics exhibited optimum electrical properties (d33=252 pC/N, εr=1450, tan δ=0.02, and TC=280 °C). These results reveal that (1?x)Na0.47K0.47Li0.06NbO3–xAgSbO3 ceramics are promising materials for lead-free piezoelectric application. 相似文献
4.
Yongjie Zhao Yuzhen ZhaoRongxia Huang Rongzheng LiuHeping Zhou 《Journal of the European Ceramic Society》2011,31(11):1939-1944
The effects of sintering temperature and the addition of CuO on the microstructure and piezoelectric properties of 0.95(K0.5Na0.5)NbO3-0.05Li(Nb0.5Sb0.5)O3 were investigated. The KNN-5LNS ceramics doped with CuO were well sintered even at 940 °C. A small amount of Cu2+ was incorporated into the KNN-5LNS matrix ceramics and XRD patterns suggested that the Cu2+ ion could enter the A or B site of the perovskite unit cell and replace the Nb5+ or Li+ simultaneously. The study also showed that the introduction of CuO effectively reduced the sintering temperature and improved the electrical properties of KNN-5LNS. The high piezoelectric properties of d33 = 263 pC/N, kp = 0.42, Qm = 143 and tan δ = 0.024 were obtained from the 0.4 mol% CuO doped KNN-5LNS ceramics sintered at 980 °C for 2 h. 相似文献
5.
Piezoelectric energy harvesting is the most widely investigated technology for renewable energy applications. In this work, (1-x)(Na0.5K0.5)NbO3-xLiSbO3 piezoelectric ceramics were prepared through conventional mixed oxide fabrication methods with different sintering temperatures. Although the (Na0.5K0.5)NbO3 piezoelectric material is representative among the lead-free ceramics, it is difficult to densify by typical sintering techniques owing to its easy evaporation properties of potassium (K+) and sodium ion (Na+). Hence, lithium (Li+) and antimony ion (Sb5+) were used for the partial substitution of (Na0.5K0.5)NbO3. With the optimized sintering temperature, Li+ and Sb5+ are expected to be crucial in increasing the density and enhance the piezoelectric and ferroelectric properties. In this study, the phase, microstructure, and dielectric and electrical properties of (1-x)(Na0.5K0.5)NbO3-xLiSbO3 ceramics depending on the sintering temperature is examined by employing X-ray diffraction, field emission scanning electron microscopy, impedance analyzer, and mechanical force system for energy harvesting. 相似文献
6.
(0.974−x)(K0.5Na0.5)NbO3–0.026Bi0.5K0.5TiO3–xSrZrO3 lead-free piezoelectric ceramics have been prepared by the conventional solid state sintering method. Systematic investigation on the microstructure, crystalline structures as well as electrical properties of the ceramics was carried out. With the addition of SrZrO3, the rhombohedral–orthorhombic phase transition temperature of the ceramics increases. Both the rhombohedral–orthorhombic and orthorhombic–tetragonal phase transitions of the ceramics were modified to be around room temperature when x~0.05, and as a result remarkably strong piezoelectricity has been obtained in 0.924(K0.5Na0.5)NbO3–0.026Bi0.5K0.5TiO3–0.05SrZrO3 ternary system, whose piezoelectric parameters were d33=324 pC/N and kp=41%. 相似文献
7.
Xuming Pang Jinhao Qiu Kongjun Zhu Honghui Gu 《Journal of Inorganic and Organometallic Polymers and Materials》2013,23(2):463-466
(K0.5Na0.5)NbO3 piezoelectric ceramics can be sintered at a temperature as low as 750 °C for 5 h by incorporating Li2CO3 + Bi2O3 + ZnO as the sintering aid, whereas the conventional sintering temperature is around 1,100 °C. The optimal “soft” piezoelectric properties are obtained for ceramics sintered at 850 °C for 5 h. The dielectric permittivity (ε), piezoelectric coefficient (d 33), electromechanical coupling (k p) and mechanical quality factors (Q m) of (K, Na)NbO3 modified with 5.5 wt% sintering aids are 1,436, 90 pC/N, 0.3 and 10, respectively. These values are similar to the values obtained for (K0.5Na0.5)NbO3 ceramics sintered above 1,100 °C. The underlying mechanism for abrupt change of dielectric permittivity is explained. 相似文献
8.
The effects of calcination temperature on the bulk density, piezoelectric, and ferroelectric properties were investigated for the Ag2O doped 0.94(K0.5Na0.5)NbO3–0.06LiNbO3 ceramics. The calcination temperatures were varied from 750 to 950 °C by 50 °C differences. An tetragonal XRD pattern, consistent with single-phase 0.94(K0.5Na0.5)NbO3–0.06LiNbO3 was obtained after calcination at 850 °C for 2 h. And the experimental results showed that Ag2O doped 0.94(K0.5Na0.5)NbO3–0.06LiNbO3 ceramics calcined at 850 °C had a remnant polarization Pr=24.5 μC/cm2, bulk density=4.32 g/cm3, piezoelectric constant d33=282 pC/N and electromechanical coefficient kp=37.8%. 相似文献
9.
In this work, Li-modified KNN ceramic compositions ((K0.5Na0.5)1−xLix)NbO3 with x = 0.03, 0.04, 0.05, 0.06, 0.65 and 0.07 were prepared by a conventional solid-state mixed-oxide method. The structural phase formation and microstructure were characterized by X-ray diffraction technique (XRD) and scanning electron microscopy (SEM). It has been found that a morphotropic phase boundary (MPB) between orthorhombic phase and tetragonal phases should exist between compositions with Li contents of 6-6.5%. The Curie temperature (Tc) of the ceramics shifted to higher temperature with increasing Li content. The room temperature dielectric constant was also seen to be higher than the pure KNN ceramics. In addition, the ferroelectric properties were found to enhance at near MPB compositions. This study clearly showed that the addition of Li could improve the dielectric and ferroelectric properties in (K0.5Na0.5)NbO3 ceramics. 相似文献
10.
11.
The phase transition temperature and piezoelectric properties of x(Bi1/2Na1/2)TiO3–y(Bi1/2Li1/2)TiO3–z(Bi1/2K1/2)TiO3 [x + y + z = 1] (abbreviated as BNLKT100y–100z) ceramics were investigated. BNLKT100y–100z ceramics were prepared by conventional ceramic fabrication. The depolarization temperature Td was determined by the temperature dependence of the dielectric and piezoelectric properties. This study focuses on the effect of Li1+ and K1+ ions on Td and the piezoelectric properties of BNT ceramics. BNLKT100y–100z (y = 0–0.08) has a morphotropic phase boundary (MPB) between rhombohedral and tetragonal phases at z = 0.18–0.20, and high piezoelectric properties were obtained at the MPB composition. The piezoelectric constant d33 increased with increasing y; however, Td decreased above y = 0.06. The d33 and Td values of BNLKT4-20 and BNLKT8-20 were 176 pC/N and 171 °C, and 190 pC/N and 115 °C, respectively. 相似文献
12.
Jeong-Ho Cho Yoo-Jung Choi Young-Jin Lee Young-Hun Jeong Myoung-Pyo Chun Joong-Hee Nam Byung-Ik Kim 《Ceramics International》2012
Li0.02(KxNa1?x)0.98NbO3(x = 0.35–0.55) ceramics were prepared using the conventional solid state sintering method. The thermal behaviors of Li-modified (KxNa1?x)NbO3 ceramics were investigated from ?30 to 150 °C, and the effect of Na/K ratio in (KxNa1?x)NbO3 ceramics on thermal behavior and electrical properties was also studied. In the case of Li0.02(KxNa1?x)0.98NbO3 ceramics with 0.5 wt.% ZnO, the transition temperature was sharply decreased because of a phase transition as the composition range of x was 0.425–0.475. From the results of the temperature dependence of piezoelectric properties, it is assumed that the Na-rich phase is less stable than the K-rich phase for temperature change. 相似文献
13.
Tao Chen Hongli Wang Ting Zhang Guangchang Wang Jifang Zhou Jianwei Zhang Yuhong Liu 《Ceramics International》2013
(1−x)K0.50Na0.50NbO3–xBa0.80Ca0.20ZrO3 [(1−x)KNN–xBCZ] lead-free ceramics were prepared by the conventional solid-state method, and the effect of BCZ content on their phase structure and piezoelectric properties was studied. A coexistence of rhombohedral–orthorhombic phases was identified in the range 0.04<x<0.08. With increasing the BCZ content, their grain size becomes smaller, and their Curie temperature gradually decreases. An optimum piezoelectric behavior of d33∼197 pC/N and kp∼40.6% was demonstrated in the ceramic with x=0.06 because of the coexistence of two phases. As a result, the introduction of BCZ could further improve piezoelectric properties of KNN ceramics. 相似文献
14.
Jialiang Zhang Yalin Qin Yong Gao Weizeng Yao Minglei Zhao 《Journal of the American Ceramic Society》2014,97(3):759-764
A modified two‐step sintering (MTSS) technique was attempted to fabricate dense (K,Na)NbO3‐based lead‐free ceramics through the solid‐state reaction route. (K0.50Na0.50)0.98Li0.02(Nb0.795Ta0.18Sb0.025)O3 and (K0.45Na0.55)0.98Li0.02Nb0.77Ta0.18Sb0.05O3 were chosen as the test chemical compositions, and high relative density values over 97.5% were successfully obtained in their corresponding ceramics. Consequently, the d33 values were enhanced considerably and reached 353 and 436 pC/N, respectively. The latter d33 value is a record one ever achieved in the (K,Na)NbO3‐based ceramic materials so far. Furthermore, observation analyses of microstructure and domain patterns were carried out and showed that partial depoling occurs more easily in large grains than in small ones. In particular, it was found that the (K0.50Na0.50)0.98Li0.02(Nb0.795Ta0.18Sb0.025)O3 ceramic densified by MTSS has a quite uniform grain‐size distribution with comparatively small grains and exhibits the very excellent time‐aging stability. The study results suggest that microstructure with high relative density and suitably suppressed grain sizes is desirable for further acquiring the superior KNN‐based ceramics of both excellent piezoelectric properties and good depoling stabilities. 相似文献
15.
Ying-Chieh Lee Tai-Kuang LeeJhen-Hau Jan 《Journal of the European Ceramic Society》2011,31(16):3145-3152
This article studies the microstructure and piezoelectric properties of a ceramic lead-free NBT under different amount of ZnO doping. X-ray diffraction shows that Zn2+ diffuses into the lattice of (Bi0.5Na0.5)TiO3 to form a solid solution with a pure perovskite structure. By modifying the zinc oxide content, the sintering behavior of (Bi0.5Na0.5)TiO3 ceramics was significantly improved and the grain size was increased. The piezoelectric coefficient d33 for the 1.0 wt.% ZnO-doped (Bi0.5Na0.5)TiO3 ceramics sintered at 1050 °C was found to be 95 pC/N, and the electromechanical coupling factor kp = 0.13. However, the piezoelectric coefficient d33 for the 0.5 wt.% ZnO-doped (Bi0.5Na0.5)TiO3 ceramics sintered at 1140 °C was found to be 110 pC/N, and the electromechanical coupling factor kp = 0.17. 相似文献
16.
Eu-doped (Bi0.5Na0.5)0.94Ba0.06TiO3 (BNBT6-xEu, x=0.00–2.00 at%) lead-free piezoelectric ceramics have been synthesized by the solution combustion method. The effect of Eu doping concentration on the phase structure, microstructure and electrical properties of BNBT6 ceramics has been investigated. The XRD analysis confirms that the europium additive incorporates into the BNBT6 lattice and results in a phase transition from the coexistence of rhombohedral and tetragonal phases to a more symmetric pseudocubic phase. The SEM images indicate that the europium additive has little effect on the ceramic microstructure and the average grain size is about 2.0 μm. The electrical properties of BNBT6 ceramics can be improved by appropriate Eu doping. The 0.25 at% Eu doped BNBT6 ceramic presents excellent electrical properties: piezoelectric constant d33=149 pC/N, remnant polarization Pr=40.27 μC/cm2, coercive field Ec=2.95 kV/mm, dielectric constant εr=1658 and dissipation factor tan δ=0.0557 (10 kHz). 相似文献
17.
The screen-printing multilayer grain growth (MLGG) technique is successfully applied to alkaline niobate lead-free piezoelectric ceramics. Highly textured (K0.5Na0.5)NbO3 (KNN) ceramics with 〈0 0 1〉 orientation (f = 93%) were fabricated by MLGG technique with plate-like NaNbO3 templates. The influence of sintering temperature on grain orientation and microstructure was studied. The textured KNN ceramics showed very high piezoelectric constant d33 = 133 pC/N, and high electromechanical coupling factor kp = 0.54. These properties were superior to those of conventional randomly oriented ceramics, and reach the level of those of textured KNN ceramic prepared by tape-casting technique. Compared with other grain orientation techniques, screen-printing is a simple, inexpensive and effective method to fabricate grain oriented lead-free piezoelectric ceramics. 相似文献
18.
Xiaopeng Wang Jiagang WuXiaojing Cheng Binyu ZhangJianguo Zhu Dingquan Xiao 《Ceramics International》2013
(K0.50Na0.50)0.97Bi0.01(Nb1-xZrx)O3 (KNBNZ) lead-free ceramics were prepared by the conventional solid-state sintering process. Their phase structure is dependent on the Zr content in the investigated range, and the ceramics endure a phase transition from pseudocubic to orthorhombic with increasing Zr content. Improved piezoelectric properties have been observed when the poling temperature is located at ~100 °C because of the coexistence of orthorhombic and tetragonal phases. Their dielectric and piezoelectric properties were enhanced by doping Zr, the ceramic with x=0.02 showing optimal electrical properties, i.e., d33~161 pC/N, kp~0.41, Qm~81, Tc~370 °C, and To−t~130 °C. These results show that the KNBNZ ceramic is a promising lead-free piezoelectric material. 相似文献
19.
Li/Ta/Sb co-doped lead-free (K0.4425Na0.52Li0.0375)(Nb0.93−xTaxSb0.07)O3 (abbreviated KNLNSTx) piezoelectric ceramics, with Ta-doping ratio of x ranging from 0.0275 to 0.0675, were synthesized using the conventional solid-state reaction method at the sintering temperature of 1130 °C. The effects of Ta content on the microstructure, dielectric properties, and phase transition behavior of the prepared ceramics were systematically investigated. The X-ray diffraction results show that all KNLNSTx ceramics formed a secondary phase, which is assigned to the tetragonal tungsten-bronze type (TTB) structure phase, and showed a phase transition from an orthorhombic symmetry to a tetragonal symmetry across a composition region of 0.0375<x<0.0475. The grain shape and size that correspond to the phase structure transformations can be clearly observed in the scanning electron microscopy images. As x increased to 0.0475, the KNLNST0.0475 ceramics changed from orthorhombic to tetragonal structure and showed excellent piezoelectric properties of d33=313 pC/N, kp=47%, and εr=1825. By contrast, samples of x=0.0375 with orthorhombic symmetry exhibited poor piezoelectric properties, with d33=200 pC/N and εr=1015. These results indicate that phase structure is vital in the piezoelectric properties of KNN lead-free ceramics. 相似文献
20.
《Ceramics International》2022,48(7):9324-9329
(K,Na)NbO3 (KNN)-based ceramics have been proven to be formidable candidates among lead-free piezoelectric materials, yet poor reproducibility always hinders their progress. In the present study, the effects of low lithium substitution on the electrical properties and microstructure of (K0.5Na0.5)1-xLixNbO3 (KNLN) ceramics were investigated. All samples were synthesized by the sol-gel method. The Curie temperature (TC) of the ceramics shifted to higher temperature and gradually decreased the monoclinic-tetragonal (TM-T) phase transition. Li+ substitution had a prominent effect on the ferroelectric properties and improved the piezoelectric coefficient (d33) up to 181 pC/N. X-Ray Diffraction (XRD) studies and Field Emission Scanning Electron Microscopy (FESEM) images revealed an inevitable tetragonal tungsten bronze (TTB) secondary phase, which was formed during the preparation process. It was demonstrated that the volatilization of Li+ cations facilitated TTB growth. The coexistence of two different phase structures proved to enhance the KNN piezoelectric performance. 相似文献