共查询到20条相似文献,搜索用时 15 毫秒
1.
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
2.
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
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.
Pornsuda Bomlai Penprapa Sinsap Supasarute Muensit Steven J. Milne 《Journal of the American Ceramic Society》2008,91(2):624-627
Lead-free piezoelectric ceramics in the system 0.95Na0.5 K0.5 NbO3 –0.05LiTaO3 were modified with ≤1 mol% MnO. Maximum densities occurred at a sintering temperature of 1050°C. Characteristic changes in the relative intensity of X-ray diffraction peaks were consistent with Mn ions substituting on the perovskite lattice to produce a change from orthorhombic to a mixture of tetragonal and orthorhombic phases. Grain growth during secondary recrystallization was also affected, leading to increased grain sizes. The dielectric constant increased from ∼600 in unmodified ceramics to ∼1040 in ceramics prepared with 0.5 mol% MnO. 相似文献
5.
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
6.
Ya-Ru Zhang Jing-Feng Li Bo-Ping Zhang 《Journal of the American Ceramic Society》2008,91(8):2716-2719
Conventional sintering of (Na1− x K x )0.5 Bi0.5 TiO3 (abbreviated as NKBT x , x =18–22 mol%) lead-free piezoelectric ceramics was investigated to clarify the optimal sintering temperature for densification and electrical properties. Both sintered density and electrical properties were sensitive to sintering temperature; particularly, the piezoelectric properties deteriorated when the ceramics were sintered above the optimum temperature. The NKBT20 and NKBT22 ceramics synthesized at 1110°–1170°C showed a phase transition from tetragonal to rhombohedral symmetry, which was similar to the morphotropic phase boundary (MPB). Because of such MPB-like behavior, the highest piezoelectric constant ( d 33 ) of about 192 pC/N with a high electromechanical coupling factor ( k p ) of about 32% were obtained in the NKBT22 ceramics sintered at 1150°C. 相似文献
7.
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
8.
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
9.
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
10.
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
11.
Lead-free (Na0.52 K0.48− x )(Nb1− x − y Sb y )O3 - x LiTaO3 (NKNS–LT) piezoelectric ceramics have been fabricated by ordinary sintering. A special attention was paid to the composition design through which the dielectric and piezoelectric properties of the (Li, Ta, Sb) modified NKN systems were significantly promoted. A property spectrum was generated with a particular discussion on the relationship between the Sb content, the LT content, the polymorphic phase transition, and the electrical properties and their temperature stability. Excellent and tunable electrical properties of d 33 =242–400 pC/N, k p =36%–54%, , and T c =230°–430°C demonstrate a tremendous potential of the compositions studied for device applications. 相似文献
12.
Jun-Hai Lv Mei Zhang Min Guo Wen-Chao Li Xi-Dong Wang 《International Journal of Applied Ceramic Technology》2007,4(6):571-577
NaNbO3 , KNbO3 , and K x Na(1− x ) NbO3 powders were successfully prepared by the hydrothermal method. The phase of the products was identified to be orthorhombic structure by X-ray diffraction (XRD) technique, and the XRD results revealed that the x value of the K x Na(1− x ) NbO3 gradually increased with the increase in the ratio of K+ to Na+ in alkaline solution. The morphology and the microstructure were investigated by scanning electron microscopy, energy-dispersive spectroscopy, and transmission electron microscopy, and the results indicated that the ratio of K+ to Na+ in the solution had a great effect on the morphology and the size of products. Na0.5 K0.5 NbO3 with morphotropic phase boundary composition could be synthesized when the molar ratio of K+ to Na+ was between 4:1 and 6:1 in the solution. A possible formation mechanism of the K x Na(1− x ) NbO3 crystal was also proposed based on the experimental results. 相似文献
13.
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
14.
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
15.
Piezoelectric ceramics Na1− x Ba x Nb1− x Ti x O3 with low BaTiO3 concentrations x have been prepared by the solid-state reaction method, and their ferroelectric and piezoelectric properties have been studied. The ceramics are classic ferroelectrics when x ≤0.10, and the ferroelectric–paraelectric phase transition becomes diffusive when x ≥0.15. A low doping level of BaTiO3 changes the NaNbO3 ceramics from antiferroelectric to ferroelectric. With the increase in BaTiO3 doping level, the Curie temperature of ceramics decreases linearly and the remnant polarization and coercive field also decrease, while their dielectric constant increases. Na0.9 Ba0.1 Nb0.9 Ti0.1 O3 ceramics show the largest piezoelectric constant d 33 (147 pC/N) and good sinterability, suggesting that it is a good candidate for lead-free piezoelectric ceramics. 相似文献
16.
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
17.
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
18.
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
19.
Jiangtao Zeng Yanghong Zhang Liaoying Zheng Gurong Li Qingrui Yin 《Journal of the American Ceramic Society》2009,92(3):752-754
(1− x )K0.5 Na0.5 NbO3 – x K3 Li2 Nb5 O15 (KNN–100 x KLN) ceramics were prepared by the solid-state reaction method. The results showed that small amount of KLN ( x ≤0.02) incorporated into the lattice and formed a single phase perovskite structure. The KLN modification lowered the phase transition temperature of orthorhombic–tetragonal ( T O−T ) and increased the Curie temperature ( T c ), but the transition temperatures remained almost unchanged in the range of x from 0.02 to 0.03. Small amount of KLN decreased the amount of defects, thus the remnant polarization increased and the coercive field decreased markedly, and the piezoelectric properties of KNN ceramics modified by small amount of KLN also enhanced markedly. 相似文献
20.
Li/Ta-codoped lead-free (Na,K)NbO3 ceramics with a nominal composition of [(Na0.535 K0.480 )0.942 Li0.058 ](Nb0.90 Ta0.10 )O3 were synthesized normally at 1070°–1100°C. The XRD patterns of all samples show a single pervoskite structure with tetragonal symmetry. Although MPB separating the orthorhombic and tetragonal symmetries was absent, the maximum piezoelectric coefficient ( d 33 ), electromechanical coupling coefficient ( k p ), Curie temperature ( T c ), and remanent polarization ( P r ) were optimized as 216 pC/N, 38.1%, 445°C, and 8.73 μC/cm2 , respectively. 相似文献