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1.
Ruzhong Zuo Xusheng Fang Chun Ye Longtu Li 《Journal of the American Ceramic Society》2007,90(8):2424-2428
(1− x )(Na0.5 K0.5 )NbO3 –(Bi0.5 K0.5 )TiO3 solid solution ceramics were successfully fabricated, exhibiting a continuous phase transition with changing x at room temperature from orthorhombic, to tetragonal, to cubic, and finally to tetragonal symmetries. A morphotropic phase boundary (MPB) between orthorhombic and tetragonal ferroelectric phases was found at 2–3 mol% (Bi0.5 K0.5 )TiO3 (BKT), which brings about enhanced piezoelectric and electromechanical properties of piezoelectric constant d 33 =192 pC/N and planar electromechanical coupling coefficient k p =45%. The MPB composition has a Curie temperature of 370°–380°C, comparable with that of the widely used PZT materials. These results demonstrate that this system is a promising lead-free piezoelectric candidate material. 相似文献
2.
Pornsuda Bomlai Pattraporn Wichianrat Supasarute Muensit Steven J. Milne 《Journal of the American Ceramic Society》2007,90(5):1650-1655
Sodium-potassium niobate [Na0.5 K0.5 NbO3 ] powders were prepared following the conventional mixed oxide method. An orthorhombic XRD pattern, consistent with single-phase Na0.5 K0.5 NbO3 , was obtained after calcination at 900°C for 6 h. Introducing 5 mol% excess Na2 CO3 and K2 CO3 into the starting mixture allowed milder calcination conditions to be used, for example 800°C for 2 h. Primary particles in 5 mol% excess samples were cuboid, with maximum sizes of ∼2.5 μm. Equiaxed 0.3–0.4-μm particles were formed for non-excess powders, and also for powders prepared with 1 and 3 mol% excess alkali carbonates. The results suggest liquid formation during calcination of the excess 5-mol% starting powders. 相似文献
3.
Xueyi Sun Jun Chen Ranbo Yu Ce Sun Guirong Liu Xianran Xing Lijie Qiao 《Journal of the American Ceramic Society》2009,92(1):130-132
Lead-free potassium sodium niobate-based piezoelectric ceramics (1− x )(Na0.5 K0.5 )NbO3 – x BiScO3 (KNN–BS) ( x =0∼0.05) have been prepared by an ordinary sintering process. Single perovskite phase of KNN–BS exhibits an orthorhombic symmetry at x <0.015 and pseudocubic symmetry at x >0.02, separating by a MPB at 0.015≤ x ≤0.02. Piezoelectric and ferroelectric properties are significantly enhanced in the MPB, which are as follows: piezoelectric constant d 33 =203 pC/N, planar coupling coefficient k p =0.36, remnant polarization P r =24.4 μC/cm2 . These solid solution ceramics look promising as a potential lead-free candidate materials. 相似文献
4.
Yuanyu Wang Qibin Liu Jiagang Wu Dingquan Xiao Jianguo Zhu 《Journal of the American Ceramic Society》2009,92(3):755-757
(1− x )(Na0.5 K0.5 )NbO3 – x AgSbO3 lead-free piezoelectric ceramics were prepared by normal sintering. The effects of the AgSbO3 on the phase structure and piezoelectric properties of the ceramics were systematically studied. These results show that the AgSbO3 -modified (K0.50 Na0.50 )NbO3 lead-free piezoelectric ceramics form stable solution with orthorhombic structure, and the Curie temperature and the polymorphic phase transition of the ceramics decreased with increasing AgSbO3 . The result shows that the piezoelectric properties of the ceramics strongly depend on the AgSbO3 . The ceramics with x =0.05 possess optimum properties ( d 33 =192 pC/N, k p =43%, T c =348°C, T o−t =145°C, ɛr ∼632, and tan δ∼3.5%). These results indicate that the ceramic is a promising candidate material for lead-free piezoelectric ceramics. 相似文献
5.
Xueyi Sun Jinxia Deng Ce Sun Jichao Li Jun Chen Ranbo Yu Guirong Liu Xianran Xing Lijie Qiao 《Journal of the American Ceramic Society》2009,92(8):1853-1855
Lead-free potassium sodium niobate-based piezoelectric ceramics (1− y )(Na0.5−0.5 x K0.5−0.5 x Li x )NbO3 − y BiScO3 ( y =0.01, x= 0–0.06) have been prepared by an ordinary sintering process. The XRD analysis showed that the structure changes from orthorhombic to tetragonal with the increase of x (at y =0.01, abbreviated as KNNBSL100 x ). At room temperature, the polymorphic phase transition from the orthorhombic to the tetragonal phase was identified at approximately 0.02≤ x ≤0.04. The piezoelectric and ferroelectric properties were significantly enhanced. The temperature dependences of the relative permittivity revealed that the Curie temperature was increased with the addition of LiNbO3 . These solid solution ceramics are promising as potential lead-free candidate materials. 相似文献
6.
Dunmin Lin Kin Wing Kwok Helen Wong Lai-wa Chan 《Journal of the American Ceramic Society》2009,92(6):1362-1365
In this work, the double-loop-like characteristics of K0.5 Na0.5 NbO3 + x mol% K5.4 Cu1.3 Ta10 O9 ceramic and its relationships with the transition temperature, aging, and switching have been investigated. Our results reveal that the phase transition temperature is an important parameter determining the aging requirement for the ceramics to exhibit the double-loop-like characteristics. For a ceramic with a high transition temperature, e.g. the ceramic with x =0.75 (tetragonal–orthorhombic phase temperature ∼206°C), the vacancies can migrate during the crystal transformation and settle in a distribution with the same symmetry as the crystal after the transformation. As a result, defect dipoles along the polarization direction are formed and provide restoring forces to reverse the switched polarizations, and thus producing a double polarization hysteresis ( P – E ) loop. On the other hand, aging is required for a ceramic with a low transition temperature, e.g. aging at 80°C for 30 days is required for the ceramic with x =1.5 (transition temperature ∼175°C). Our results also reveal that the defect dipoles can be switched under a slow-switching electric field (<1 Hz) or at high temperatures (>100°C), thus leading to an opening of the double P – E loop. 相似文献
7.
Mankang Zhu Liying Liu Yudong Hou Hao Wang Hui Yan 《Journal of the American Ceramic Society》2007,90(1):120-124
Microstructure and electrical properties of manganese oxide (MnO)-doped (Na0.5 Bi0.5 )0.92 Ba0.08 TiO3 (NBBT) piezoceramics were investigated in this work. X-ray diffraction analysis shows that the suitable substitution of Mn ion into the B site induces the lattice distortion of perovskite NBBT: the solution limit is at 0.3 wt% MnO. Besides, it is observed that the sintering properties can be improved by adding a small amount of MnO, thus increasing the grain size and the relative density. Further, the temperature dependence of the dielectric permittivity of NBBT ceramics indicates that the MnO addition reconstructs the disorder array destroyed by joining BaTiO3 in the Na0.5 Bi0.5 TiO3 system due to the sizable radius of the B-site cations. Combining these effects of MnO addition, the optimal electrical properties were acquired for NBBT ceramic with addition of 0.30 wt% MnO. The excellent electrical properties of MnO-doped NBBT ceramics indicate its promising application in large displacement actuators. 相似文献
8.
Hongliang Du Daijun Liu Fusheng Tang Dongmei Zhu Wancheng Zhou Shaobo Qu 《Journal of the American Ceramic Society》2007,90(9):2824-2829
Lead-free piezoelectric (K0.5 Na0.5 )NbO3 – x wt% Bi2 O3 ceramics have been synthesized by an ordinary sintering technique. The addition of Bi2 O3 increases the melting point of the system and improves the sintering temperature of (K0.5 Na0.5 )NbO3 ceramics. All samples show a pure perovskite phase with a typical orthorhombic symmetry when the Bi2 O3 content <0.7 wt%. The phase transition temperature of orthorhombic–tetragonal ( T O − T ) and tetragonal–cubic ( T C ) slightly decreased when a small amount of Bi2 O3 was added. The remnant polarization P r increased and the coercive field E c decreased with increasing addition of Bi2 O3 . The piezoelectric properties of (K0.5 Na0.5 )NbO3 ceramics increased when a small amount of Bi2 O3 was added. The optimum piezoelectric properties are d 33 =140 pC/N, k p =0.46, Q m =167, and T C =410°C for (K0.5 Na0.5 )NbO3 –0.5 wt% Bi2 O3 ceramics. 相似文献
9.
Kouichi Harada Hideyuki Kanai Yohachi Yamashita 《Journal of the American Ceramic Society》1996,79(8):2109-2112
An aging model for relaxors is suggested on the basis of the transformation of a supercooled cubic lattice into a tetragonal lattice. Manganese ions distort the crystal lattice, and the distortion affects the phase transformation rate. As a result, the aging rate may be expected to change. The lattice constant of (Pb0.63 Ba0.37 )(Zr0.7 Ti0.3 )O3 +χ MnO mol% dielectric ceramics was used as a measure of the degree of the distortion. As the lattice constant decreased up to 0.5 MnO mol%, the aging rate increased, justifying the proposed model. 相似文献
10.
Hwi-Yeol Park Joo-Young Choi Min-Kyu Choi Kyung-Hoon Cho Sahn Nahm Hyeung-Gyu Lee Hyung-Won Kang 《Journal of the American Ceramic Society》2008,91(7):2374-2377
When a small amount of CuO was added to (Na0.5 K0.5 )NbO3 (NKN) ceramics sintered at 960°C for 2 h, a dense microstructure with increased grains was developed, probably due to liquid-phase sintering. The Curie temperature slightly increased when CuO exceeded 1.5 mol%. The Cu2+ ion was considered to have replaced the Nb5+ ion and acted as a hardener, which increased the E c and Q m values of the NKN ceramics. High piezoelectric properties of k p =0.37, Q m =844, and ɛ3 T /ɛ0 =229 were obtained from the specimen containing 1.5 mol% of CuO sintered at 960°C for 2 h. 相似文献
11.
The fracture strengths of sintered Al2 O3 containing 20 and 40 vol% ZrO2 (12 mol% CeO2 )—zirconia-toughened alumina (ZTA)—composites along with the fracture resistance can be increased (e.g., to ∼900 MPa and >12 Mpa·m1/2 , respectively), by increasing the mean grain size of the t -ZrO2 (and the Al2 O3 ) from ∼0.5 μm to ∼3 μm. At these lower t -ZrO2 contents, the fracture strength-fracture resistance curves show a continuous rise as opposed to the strength maxima observed in polycrystalline t -ZrO2 (12 mol% CeO2 ), CeTZP, and ZrO2 (12 mol% CeO2 ) ceramics containing ≤20 vol% Al2 O3 . The toughened composites also exhibit excellent damage resistance with fracture strengths of 500 MPa retained with surfaces containing ∼150- N Vickers indentations which produce cracks of ∼160-μm radius. Greater damage resistance correlates with an increase in the apparent R -curve response of these composites. 相似文献
12.
Jing-Feng Li Ke Wang Bo-Ping Zhang Li-Min Zhang 《Journal of the American Ceramic Society》2006,89(2):706-709
Lead-free piezoelectric ceramics have received attention because of increasing interest in environmental protection. Niobate ceramics such as NaNbO3 and KNbO3 have been studied as promising Pb-free piezoelectric ceramics, but their sintering densification is fairly difficult. In the present study, highly dense Na0.5 K0.5 NbO3 ceramics were prepared using spark plasma sintering (SPS). Although the SPS temperature was as low as 920°C, the density of the Na0.5 K0.5 NbO3 solid solution ceramics was raised to 4.47 g/cm3 (>99% of the theoretical density). After post-annealing in air, reasonably good ferroelectric and piezoelectric properties were obtained in the Na0.5 K0.5 NbO3 ceramics with submicron grains. The crystal phase of the Na0.5 K0.5 NbO3 has an orthorhombic structure. The Curie temperature is 395°C and the piezoelectric parameter ( d 33 ) of the Na0.5 K0.5 NbO3 ceramics reached 148 pC/N. 相似文献
13.
Hwi-Yeol Park In-Tae Seo Jae-Hong Choi Sahn Nahm Hyeung-Gyu Lee 《Journal of the American Ceramic Society》2010,93(1):36-39
(Na0.5 K0.5 )NbO3 (NKN) ceramic with 1.5 mol% CuO added (NKNC) was well sintered even at a low temperature of 900°C with the addition of ZnO. Most of the ZnO reacted with the CuO and formed the liquid phase that assisted the densification of the specimens at 900°C. A few Zn2+ ions entered the matrix of the specimens and increased the coercive field ( E c ) and Q m values of the specimens. High-piezoelectric properties of k p =0.37, Q m =755, and ɛ3 T /ɛ0 =327 were obtained from the NKNC ceramics containing 1.0 mol% ZnO sintered at 900°C for 2 h. 相似文献
14.
Xuhai Li Meng Jiang Jing Liu Jiliang Zhu Xiaohong Zhu Jianguo Zhu Dingquan Xiao 《Journal of the American Ceramic Society》2009,92(7):1625-1628
Mn-doped 0.98K0.5 Na0.5 NbO3 –0.02BiScO3 (0.98KNN–0.02BS) lead-free piezoelectric ceramics have been prepared by a conventional sintering technique and the effects of Mn doping on the phase structure and piezoelectric properties of the ceramics have been studied. Our results reveal that a small amount of Mn can improve the densification of the ceramics effectively. Because of the high densification, fine grain, and Mn doping effects, the piezoelectric and dielectric properties of the ceramics are improved considerably. Very good piezoelectric and dielectric properties of d 33 =288 pC/N, k p =0.46, ɛr =1591, and T C =328°C were obtained for the 0.98KNN–0.02BS ceramics doped with 0.8 mol% Mn. Therefore, the 0.98KNN–0.02BS ceramics containing a small amount of Mn are a good candidate material for lead-free piezoelectric ceramics. 相似文献
15.
Yuanhua Lin Ce-Wen Nan Jianfei Wang Gang Liu Junbo Wu Ning Cai 《Journal of the American Ceramic Society》2004,87(4):742-745
The dielectric properties of Na0.5 Bi0.5 TiO3 (NBT) -based composites incorporating silver particles prepared by sintering at a low temperature of ∼900°C are reported. The dielectric constant increases with the amount of metal silver particles in the measured frequency range (150 Hz to 1 MHz), and could be enhanced up to ∼20 times higher than that of pure NBT ceramics, which was ascribed to the effective electric fields developed between the dispersed particles in the matrix and the percolation effect. Further investigation revealed that the dielectric constant of the composites has weak frequency and temperature dependence (−50°C to +50°C). 相似文献
16.
Wei Zhao Jing Ya Ying Xin Lie E Dan Zhao Heping Zhou 《Journal of the American Ceramic Society》2009,92(7):1607-1609
Textured 0.94Na0.5 Bi0.5 TiO3 –0.06BaTiO3 (NBT–6BT) ceramics were fabricated by templated grain growth (TGG) using anisotropically shaped Na0.5 Bi0.5 TiO3 (NBT) templates. Platelet NBT was synthesized by the topochemical technique, using precursor Na0.5 Bi4.5 Ti4 O15 (NBIT). The NBT particles have an average length of 10–15 μm and a thickness of 1 μm, which are suitable templates for obtaining textured ceramics (especially NBT-based ceramics) by the TGG process. This study revealed that the NBT templates are effective in inducing grain orientation in NBT–6BT ceramics. For NBT–6BT ceramics textured with 5 vol% NBT templates, a Lotgering factor of 0.87 and a d 33 of 299 pC/N are given. 相似文献
17.
Min-Soo Kim Soon-Jong Jeong Jae-Sung Song 《Journal of the American Ceramic Society》2007,90(10):3338-3340
As a candidate for lead-free piezoelectric materials, Li2 O-excess 0.95(Na0.5 K0.5 )NbO3 –0.05LiTaO3 (NKN–5LT) ceramics were developed by a conventional sintering process. The sintering temperature was lowered by adding Li2 O as a sintering aid. Abnormal grain growth in NKN–5LT ceramics was observed with varying Li2 O content. This grain-growth behavior was explained in terms of interface reaction-controlled nucleation and growth. In the 1 mol% Li2 O excess NKN–5LT samples sintered at 1000°C for 4 h in air, the electromechanical coupling factor and the piezoelectric constant of NKN–5LT ceramics were found to reach the highest values of 0.37 and 250 pC/N, respectively. 相似文献
18.
Microwave Dielectric Properties of Doped BaTi4 O9 总被引:1,自引:0,他引:1
Subodh G. Mhaisalkar Dennis W. Readey Sheikh A. Akbar 《Journal of the American Ceramic Society》1991,74(8):1894-1898
Polycrystalline BaTi4 O9 doped with Mn, Sn, Zr, Ca, Sr, and Pb was prepared from carbonates and oxides. Single-phase ceramics with densities exceeding 97% of theoretical were made with up to 3 mol% Mn; 6 mol% Sn, Zr, and Ca; and 8 mol% Sr and Pb. Dielectric constant, k , quality factor, Q , and temperature coefficient of frequency, τ f , of ∼37, 5675, and 15 ppm/°C, respectively, were determined at 4 GHz for undoped BaTi4 O9 . Doping did not significantly affect k and τ f . However, doping with Mn, Sn, and Pb lowered Q , whereas doping with Zr, Ca, and Sr increased Q by up to 2000. Additions of 0.5 mol% MnO2 as a second phase improved Q from 3675 to 7600. 相似文献
19.
John Gerard Fisher Min-Soo Kim Ho-Yong Lee Suk-Joong L. Kang 《Journal of the American Ceramic Society》2004,87(5):937-942
Abnormal grain growth in Pb(Mg1/3 Nb2/3 )O3 –35 mol% PbTiO3 (PMN-35PT) ceramics doped with Li2 O and PbO has been investigated. Replacing the PbO dopant with up to 2 mol% Li2 O caused an increase in the number of abnormal grains. For the composition containing 2 mol% Li2 O and 6 mol% PbO, the amount of abnormal grain growth decreased with increasing sintering temperature. Single crystals of ∼6 mm × 6 mm × 2 mm thickness were grown from the 2 mol% Li2 O, 6 mol% PbO-containing composition via the templated grain growth method. Grain growth behavior with temperature is explained in terms of the effect of Li2 O on interface-reaction-controlled grain growth and the critical driving force. 相似文献
20.
Hwi-Yeol Park Cheol-Woo Ahn Kyung-Hoon Cho Sahn Nahm Hyeung-Gyu Lee Hyung-Won Kang Duk-Hee Kim Kyeong-Soon Park 《Journal of the American Ceramic Society》2007,90(12):4066-4069
The sintering temperature of 0.95(Na0.5 K0.5 )NbO3 –0.05BaTiO3 (NKN–BT) ceramics needs to be decreased below 1000°C to prevent Na2 O evaporation, which can cause difficulties in poling and may eventually degrade their piezoelectric properties. NKN–BT ceramics containing CuO were well sintered at 950°C with grain growth. Poling was easy for all specimens. Densification and grain growth were explained by the formation of a liquid phase. The addition of CuO improved the piezoelectric properties by increasing the grain size and density. High piezoelectric properties of d 33 =230 pC/N, k p =37%, and ɛ3 T /ɛ0 =1150 were obtained from the specimen containing 1.0 mol% of CuO synthesized by the conventional solid-state method. 相似文献