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1.
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
2.
Kyung-Hoon Cho Hwi-Yeol Park Cheol-Woo Ahn Sahn Nahm Kenji Uchino Seung-Ho Park Hyeung-Gyu Lee Hwack-Joo Lee 《Journal of the American Ceramic Society》2007,90(6):1946-1949
The 0.95(Na0.5 K0.5 )NbO3 –0.05SrTiO3 (0.95NKN–0.05ST) ceramics formed in this study had a porous microstructure with small grains and low piezoelectric properties due to their low density. However, when a small amount of Na2 O was intentionally subtracted from the 0.95NKN–0.05ST ceramics, a liquid phase was formed, which led to increased density and grain size. Piezoelectric properties were also improved for the Na2 O-subtracted 0.95NKN–0.05ST ceramics. The increased density and grain size were responsible for the enhancement of the piezoelectric properties. In particular, the 0.95(Na0.49 K0.5 )NbO2.995 –0.05ST ceramics showed high piezoelectric properties of d 33 =220, k p =0.4, Q m =72, and ɛ3 T /ɛo =1447, thereby demonstrating their promising potential as a candidate material for application to lead-free piezoelectric ceramics. 相似文献
3.
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
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.
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
6.
Hyun-Cheol Song Kyung-Hoon Cho Hwi-Yeol Park Cheol-Woo Ahn Sahn Nahm Kenji Uchino Seung-Ho Park Hyeung-Gyu Lee 《Journal of the American Ceramic Society》2007,90(6):1812-1816
(1− x )(Na0.5 K0.5 )NbO3 – x LiNbO3 [(1− x )NKN– x LN] ceramics were produced by the conventional solid-state sintering method, and their microstructure and piezoelectric properties were investigated. The formation of the liquid phase and K6 Li4 Nb10 O30 second phase that were observed in the (1− x )NKN– x LN ceramics was explained by the evaporation of Na2 O during the sintering. A morphotropic phase boundary (MPB) was observed in the specimens with 0.05< x <0.08. Promising piezoelectric properties were obtained for the specimens with x =0.07. Therefore, the piezoelectric properties of this 0.93NKN–0.07LN ceramic were further investigated and were found to be influenced by their relative density and grain size. In particular, grain size considerably affected the d 33 value. Two-step sintering was conducted at different temperatures to increase the grain size. Piezoelectric properties of d 33 =240 (pC/N) and k p =0.35 were obtained for the 0.93NKN–0.07LN ceramics sintered at 1030°C and subsequently annealed at 1050°C. 相似文献
7.
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
8.
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
9.
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
10.
Bismuth sodium titanate (Bi0.5 Na0.5 TiO3 , BNT) with 0–6 at.% lanthanum was prepared by the conventional mixed oxide method. Each composition was calcined at 800–900°C for 2–5 h to form a pure perovskite phase. Green pellets were sintered at 1050–1150°C for 1–4 h to obtain dense ceramics with at least 95% of theoretical density. X–ray diffraction (XRD) showed phase distortion as lanthanum was added to this system. Meanwhile, a small amount of La was found to affect the grain size and had an influence on the poling conditions and electrical properties. The BNT–based composition with 1 at.% La doping provided a dielectric constant ( K ) of 560, a piezoelectric charge constant ( d 33 ) of 92 pC/N, and a hydrostatic piezoelectric coefficient ( d h ) of 72 pC/N. 相似文献
11.
Ruzhong Zuo Jürgen Rödel Renzheng Chen Longtu Li 《Journal of the American Ceramic Society》2006,89(6):2010-2015
Lead-free Na0.5 K0.5 NbO3 (NKN) piezoelectric ceramics were fairly well densified at a relatively low temperature under atmospheric conditions. A relative density of 96%–99% can be achieved by either using high-energy attrition milling or adding 1 mol% oxide additives. It is suggested that ultra-fine starting powders by active milling or oxygen vacancies and even liquid phases from B-site oxide additives mainly lead to improved sintering. Not only were dielectric properties influenced by oxide additives, such as the Curie temperature ( T c ) and dielectric loss ( D ), but also the ferroelectricity was modified. A relatively large remanent polarization was produced, ranging from 16 μC/cm2 for pure NKN to 23 μC/cm2 for ZnO-added NKN samples. The following dielectric and piezoelectric properties were obtained: relative permittivity ɛ T 33 /ɛ 0 =570–650, planar mode electromechanical coupling factor, k p =32%–44%, and piezoelectric strain constant, d 33 =92–117 pC/N. 相似文献
12.
Guochu Deng Qingrui Yin Aili Ding Xinsen Zheng Wenxiu Cheng Pingsun Qiu 《Journal of the American Ceramic Society》2005,88(8):2310-2314
La-doped 0.3Pb(Zn1/3 Nb2/3 )O3 –0.7Pb(Zr x Ti1− x )O3 ( x =0.5–0.53) piezoelectric ceramics with pure perovskite phase were synthesized by a two-step hot-pressing route. The piezoelectric properties of various compositions near the morphotropic phase boundary (MPB) were systematically investigated. Not only was the exact MPB of this system determined via X-ray diffractometry analysis, but also the peak of piezoelectric properties was found near the MPB. The optimum piezoelectric properties of this series were observed in the specimen with Zr/Ti=51/49. The piezoelectric coefficient ( d 33 ) and electromechanical coupling factor ( k p ) were 845 pC/N and 0.70, respectively, which have not been reported in this system so far. Large permittivity (ɛr =4088) and permittivity maximum (ɛm =29 500) were also obtained for the poled specimens. The temperatures ( T max ) of the permittivity maxima ranged from 206° to 213°C with various Zr/Ti ratios. 相似文献
13.
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
14.
Effects of La on Dielectric and Piezoelectric Properties of Pb1−x La2x/3 (Nb0.95 Ti0.0625 )2 O6 Ceramics
Gao-li Men Peng Liu Ruo-xi Zhang Hong Chen Bo Wang Jian-ping Zhou Gang-qiang Zhu 《Journal of the American Ceramic Society》2009,92(8):1753-1757
Ceramics with the chemical compositions of Pb1− x La2 x /3 (Nb0.95 Ti0.0625 )2 O6 (0≤ x ≤0.060) (PLTN) were prepared by the conventional solid-state reaction method. X-ray diffraction analysis indicated that Ti and La doping not only decreased the rhombohedral–tetragonal phase transformation temperature, but also stabilized the orthorhombic phase of PLTN ceramics. All ceramics sintered at 1190°–1250°C had shown the pure orthorhombic ferroelectric phase. La doping suppresses grain growth and inhibits the formation of pores and cracks, resulting in an increase in relative density up to 97%. The amount of La doping to PLTN ceramics obviously affect ceramics' piezoelectric constant ( d 33 ) and dielectric loss (tanδ). The sample with x =0.015 possesses high Curie temperature ( T c =560°C), low dielectric loss (tanδ=0.0054), and excellent piezoelectric constant ( d 33 =92 pC/N), presenting a high potential to be used in high-temperature applications as piezoelectric transducers. 相似文献
15.
Jiagang Wu Dingquan Xiao Yuanyu Wang Lang Wu Yihang Jiang Jianguo Zhu 《Journal of the American Ceramic Society》2008,91(7):2385-2387
[(K x Na1 − x )0.95 Li0.05 ](Nb0.95 Ta0.05 )O3 (K x NLNT) ( x= 0.40–0.60) lead-free piezoelectric ceramics were prepared by conventional solid-state sintering. The effects of K/Na ratio on the dielectric, piezoelectric, and ferroelectric properties of the K x NLNT ceramics were studied. The experimental results show that the electrical properties strongly depend on the K/Na ratio in the K x NLNT ceramics. The K x NLNT ( x =0.42) ceramics exhibit enhanced properties ( d 33 ∼242 pC/N, k p ∼45.7%, k t ∼47%, T c ∼432°C, T o−t =48°C, ɛr ∼1040, tanδ∼2.0%, P r ∼26.4 μC/cm2 , E c ∼10.3 kV/cm). Enhanced electrical properties of the K x NLNT ( x =0.42) ceramics could be attributed to the polymorphic phase transition near room temperature. These results show that the K x NLNT ( x =0.42) ceramic is a promising lead-free piezoelectric material. 相似文献
16.
Janez Bernard reja Benan Tadej Rojac Janez Holc Barbara Mali Marija Kosec 《Journal of the American Ceramic Society》2008,91(7):2409-2411
The objective of this work was to lower the sintering temperature of K0.5 Na0.5 NbO3 (KNN) without reducing its piezoelectric properties. The KNN was sintered using 0.5, 1, 2, and 4 mass% of (K, Na)-germanate. The influence of the novel sintering aid, based on alkaline germanate with a melting point near 700°C, on the sintering, density, and piezoelectric properties of KNN is presented. The alkaline-germanate-modified KNN ceramics reach up to 96% of theoretical density at sintering temperatures as low as 1000°C, which is approximately 100°C less than the sintering temperature of pure KNN. The relative dielectric permittivity (ɛ/ɛ0 ) and losses (tanδ), measured at 10 kHz, the piezo d 33 coefficient, the electromechanical coupling and mechanical quality factors ( k p , k t , Q m ) of KNN modified with 1 mass% of alkaline germanate are 397, 0.02, 120 pC/N, 0.40, 0.44, and 77, respectively. These values are comparable to the best values obtained for KNN ceramics sintered above 1100°C. 相似文献
17.
Ruzhong Zuo Chun Ye Xusheng Fang Zhenxing Yue Longtu Li 《Journal of the American Ceramic Society》2008,91(3):914-917
The Cu-modified (Na0.5 K0.5 )0.96 Li0.04 Ta0.1 Nb0.9 O3 lead-free piezoelectric ceramics were fabricated at relatively low temperatures by ordinary sintering. The results indicate that the addition of copper oxide (CuO) does not change the crystal structure and the dielectric–temperature characteristic, but tends to slightly increase the loss tangent and significantly modify the ferroelectric and electromechanical properties. Moreover, the grains get clearly coarsened with increasing CuO content. When doped with <0.25% CuO, the materials get softer with slightly decreased coercive fields ( E c ) and increased maximum electric field-driven strains ( S m ), and thus own enhanced piezoelectric properties; however, as the doping level becomes higher, the materials get harder, possessing larger E c and reduced remanent polarization and S m . The change in the electrical properties can be attributed to both the formation of oxygen vacancies by Cu2+ replacing Nb5+ and the modification of densification. 相似文献
18.
Yudong Hou Mankang Zhu Feng Gao Hao Wang Bo Wang Hui Yan Changsheng Tian 《Journal of the American Ceramic Society》2004,87(5):847-850
Pb(Zn1/3 Nb2/3 )0.20 (Zr0.50 Ti0.50 )0.80 O3 ceramics of pure perovskite structure were prepared by the two-stage method with the addition of 0–3.0 wt% MnO2 and their piezoelectric properties were investigated systematically. The MnO2 addition influences in a pronounced way both the crystal structure and the microstructure of the materials. The materials are transformed from the tetragonal to the rhombohedral structure, and the grain size is enhanced when manganese cations are added. The distortion of crystal structure for samples with MnO2 addition can be explained by the Jahn–Teller effect. The values of electromechanical coupling factor ( k p ) and dielectric loss (tan δ) are optimized for 0.5-wt%-MnO2 -doped samples ( k p = 0.60, tan δ= 0.2%) and the mechanical quality factor ( Q m ) is maximized for 1.0-wt%-MnO2 -doped samples ( Q m = 1041), which suggests that oxygen vacancies formed by substituting Mn3+ and Mn2+ ions for B-site ions (e.g., Ti4+ and Zr4+ ions) in the perovskite structure partially inhibited polarization reversal in the ferroelectrics. The ceramics with 0.50–1.0 wt% MnO2 addition show great promise as practical materials for piezoelectric applications. 相似文献
19.
Jiagang Wu Ting Peng Yuanyu Wang Dingquan Xiao Jumu Zhu Yong Jin Jianguo Zhu Ping Yu Lang Wu Yihang Jiang 《Journal of the American Ceramic Society》2008,91(1):319-321
(1− x )(K0.48 Na0.52 )(Nb0.95 Ta0.05 )O3 – x LiSbO3 [(1− x )KNNT− x LS] lead-free piezoelectric ceramics were prepared by the conventional solid-state sintering method. A morphotropic phase boundary (MPB) between orthorhombic and tetragonal phases was identified in the composition range of 0.03< x <0.05. The ceramics near the MPB exhibit a strong compositional dependence and enhanced electrical properties. The (1− x )KNNT– x LS ( x =0.04) ceramics exhibit good electrical properties ( d 33 =250 pC/N, k p =45.1%, k t =46.3%, T c =348°C, T o − t =74°C, P r =25.9 μC/cm2 , E c =10.7 kV/cm, ɛr ∼1352, tan δ∼3%). These results show that (1− x )KNNT– x LS ceramic is a promising lead-free piezoelectric material. 相似文献
20.
Dunmin Lin Kin Wing Kwok Huyong Tian Helen Wong Lai-wa Chan 《Journal of the American Ceramic Society》2007,90(5):1458-1462
Lead-free piezoelectric ceramics (Na1− x K x )(Nb1− y Sb y )O3 + z mol% MnO2 have been prepared by a conventional solid-state sintering technique. Our results reveal that Sb5+ diffuses into the K0.5 Na0.5 NbO3 lattices to form a solid solution with a single-phase orthorhombic perovskite structure. The partial substitution of Sb5+ for B-site ion Nb5+ decreases the paraelectric cubic-ferroelectric tetragonal phase transition ( T c ) and the ferroelectric tetragonal-ferroelectric orthorhombic phase transition ( T O–F ), and retains strong ferroelectricity. A small amount of MnO2 is enough to improve the densification of the ceramics. The co-effects of MnO2 doping and Sb substitution lead to significant improvements in ferroelectric and piezoelectric properties. The ceramics with x =0.45–0.525, y =0.06–0.08, and z =0.5–1 exhibit excellent ferroelectric and piezoelectric properties: d 33 =163–204 pC/N, k P =0.47–0.51, k t =0.46–0.52, ɛ=640–1053, tan δ=1.3–3.0%, P r =18.1–22.6 μC/cm2 , E c =0.72–0.98 kV/mm, and T C =269°–314°C. 相似文献