共查询到20条相似文献,搜索用时 15 毫秒
1.
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
2.
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
3.
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
4.
Wei-Chih Lee Yi-Fang Lee Min-Hui Tseng Chi-Yuen Huang Yu-Chun Wu 《Journal of the American Ceramic Society》2009,92(5):1069-1073
The crystal structure and ferroelectric properties of (1− x )(Bi0.5 Na0.5 )TiO3 – x Ba(Zr0.05 Ti0.95 )O3 (BNBZT x, x ≤12%) lead-free piezoelectric ceramics were studied. The distance between the centers of cations and anions ( d c–a ) as well as the lattice parameters was carefully investigated by Rietveld refinement on X-ray diffraction patterns. It was found that the crystal phase was determined by the amount of Ba(Zr0.05 Ti0.95 )O3 added, whereas the pure rhombohedral and tetragonal phases are observed in compositions containing x ≤4 and x ≥8%, respectively. A rhombohedral–tetragonal morphotropic phase boundary (MPB) was found at around BNBZT6, which showed a maximum and minimum d c–a at its rhombohedral and tetragonal phases, respectively. According to the present study, the ferroelectric properties show a strong dependence on their crystal phases. For the single-phase compositions, the remanent polarization ( P r ) generally increased with the value of d c–a while their coercive fields ( E c ) were determined by their lattice parameters. Nevertheless, the behavior in P r and E c for MPB compositions is related to not only the lattice parameter but also the composed phases. 相似文献
5.
Qiyi Yin Shuoguo Yuan Qiang Dong Changan Tian 《Journal of the American Ceramic Society》2010,93(1):167-170
A new type (1− x )(K0.485 Na0.485 Li0.03 )NbO3 – x Pb(Zr0.53 Ti0.47 )O3 piezoelectric ceramics was fabricated by conventional ceramics sintering technique. Their microstructure and electrical properties of the ceramics were also studied. X-ray diffraction and scanning electron microscopy patterns indicate that all ceramics samples exhibit a pure perovskite and highly dense structure, and the coexistence of the tetragonal and orthorhombic phases is formed; The ceramic with x =0.75 exhibits the following excellent properties: d 33 =363 pC/N, k p =63%, Q m =142, ɛr =1590, tan δ=1.70%, P r =28.6 μC/cm2 , E c =0.89 kV/mm, T c =295°C. These results indicate that the ceramic is a promising candidate for piezoelectric ceramics in practical applications. 相似文献
6.
Low-loss ceramics having the chemical formula Mg2 (Ti1− x Sn x )O4 for x ranging from 0.01 to 0.09 have been prepared by the conventional mixed oxide route and their microwave dielectric properties have been investigated. X-ray powder diffraction patterns indicate the corundum-structured solid solutions for the prepared compounds. In addition, lattice parameters, which linearly increase from 8.4414 to 8.4441 Å with the rise of x from 0.01 to 0.09, also confirm the forming of solid solutions. By increasing x from 0.01 to 0.05, the Q × f of the specimen can be tremendously boosted from 173 000 GHz to a maximum 318 000 GHz. A fine combination of microwave dielectric properties (ɛr ∼15.57, Q × f ∼318 000 GHz at 10.8 GHz, τf ∼−45.1 ppm/°C) was achieved for Mg2 (Ti0.95 Sn0.05 )O4 ceramics sintered at 1390°C for 4 h. Ilmenite-structured Mg(Ti0.95 Sn0.05 )O3 (ɛr ∼16.67, Q × f ∼275 000 GHz at 10.3 GHz, τf ∼−53.2 ppm/°C) was detected as a second phase. The presence of the second phase, however, would cause no significant variation in the dielectric properties of the specimen, because the second phase properties are very similar to the primary phase. These unique properties, in particular, low ɛr and high Q × f , can be utilized as a very promising dielectric material for ultra-high-frequency applications. 相似文献
7.
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
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.
Yunfei Chang Zupei Yang Lirong Xiong Zonghuai Liu Zenglin Wang 《Journal of the American Ceramic Society》2008,91(7):2211-2216
Lead-free (K0.44 Na0.52 Li0.04 )(Nb0.80− x Ta0.20 Sb x )O3 piezoelectric ceramics were prepared by the ordinary sintering method. The much higher Pauling electronegativity of Sb compared with Nb makes the ceramics more covalent. By increasing x from 0.00 to 0.06, the phase structure of the ceramics changed from the tetragonal to the pseudocubic phase, and both the bands in the Raman scattering spectra shifted to lower frequency numbers. The grain growth of the ceramics was improved by substituting Sb5+ for Nb5+ . By increasing x , the dielectric properties were optimized and the variation of dielectric constants before and after poling became smaller. Only the tetragonal–cubic phase transition was observed above room temperature in all the ɛr – T curves. The degree of diffuseness increased from 1.29 at x =0.00 to 1.96 at x =0.06, indicating that the ceramics at x =0.06 changed to an approximate ideal relaxor ferroelectric. The temperature dependences of f r and k p became better by increasing x properly. Significantly, the ceramics with x between 0.00 and 0.04 had high density and outstanding electrical properties ( d 33 =241–272pC/N, k p =0.42–0.52, ɛr =1258–1591, tan δ=0.015–0.025, T c =280°–355°C, E c =10.62–12.60 kV/cm, and P r =16.19–20.13 μC/cm2 ). Besides, the underlying mechanism for variations of the electrical properties due to Sb5+ substitution was explained in this work. 相似文献
10.
Chun-Hsu Shen Cheng-Liang Huang Chuan-Feng Shih Chih-Ming Huang 《International Journal of Applied Ceramic Technology》2009,6(5):562-570
The microstructure and microwave dielectric properties of a (1− x )(Mg0.95 Ni0.05 )TiO3 − x Ca0.6 La0.8/3 TiO3 ceramics system have been investigated. The system was prepared using a conventional solid-state ceramic route. In order to produce a temperature-stable material, Ca0.6 La0.8/3 TiO3 was added for a near-zero temperature coefficient (τf ). With partial replacement of Mg2+ by Ni2+ , the dielectric properties of the (1− x )(Mg0.95 Ni0.05 )TiO3 − x Ca0.6 La0.8/3 TiO3 ceramics can be promoted. The microwave dielectric properties are strongly correlated with the sintering temperature and the composition. An excellent Q × f value of 118,000 GHz can be obtained for the system with x =0.9 at 1325°C. For practical application, a dielectric constant (ɛr ) of 24.61, a Q × f value of 102,000 GHz, and a temperature coefficient of resonant frequency (τf ) of −3.6 ppm/°C for 0.85(Mg0.95 Ni0.05 )TiO3 −0.15Ca0.6 La0.8/3 TiO3 at 1325°C are proposed. A parallel-coupled line band-pass filter is designed and simulated using the proposed dielectric to study its performance. 相似文献
11.
The effects of substituting Nb5+ with Ta5+ on the microwave dielectric properties of the ZnNb2 O6 ceramics were investigated in this study. The forming of Zn(Nb1− x Ta x )2 O6 ( x =0–0.09) solid solution was confirmed by the measured lattice parameters and the EDX analysis. By increasing x , not only could the Q × f of the Zn(Nb1− x Ta x )2 O6 ( x =0–0.09) solid solution be tremendously boosted from 83 600 GHz at x =0 to a maximum 152 000 GHz at x =0.05, the highest ɛr ∼24.6 could also be achieved simultaneously. It was mainly due to the uniform grain morphology and the highest relative density of the specimen. A fine combination of microwave dielectric properties (ɛr ∼24.6, Q × f ∼152 000 GHz at 8.83 GHz, τf ∼–71.1 ppm/°C) was achieved for Zn(Nb0.95 Ta0.05 )2 O6 solid solution sintered at 1175°C for 2 h. 相似文献
12.
Atsushi Yokoi Junji Sugishita Akinori Kan Hirotaka Ogawa 《Journal of the American Ceramic Society》2008,91(1):160-163
The effects of V substitution for Nb on the dielectric and polarization properties of Sr0.5 Bi2.25 Na1.25 (Nb3− x V x )O12 ceramics were investigated in this study. From the X-ray powder diffraction results, no secondary phase was detected in the composition range of 0–0.075. The remanent polarizations ( P r ) of the samples in the composition range of 0–0.03 were improved by the V substitution for Nb and the highest P r value of approximately 15 μC/cm2 was obtained at x =0.03; it was noted that the V substitution for Nb was effective in improving the P r values in this ceramics. On the other hand, the coercive fields ( E c ) of the samples were on the order of approximately 40 kV/cm in such a composition range. Moreover, the anomalous variations in the dielectric constant were observed in the composition range of 0–0.075. Also, it was observed that the dielectric loss increased drastically at the temperature of approximately 500°C. 相似文献
13.
The microwave dielectric properties and the microstructures of (Mg1− x Co x )2 TiO4 ceramics prepared by the conventional solid-state route were investigated. Lattice parameters were also measured for specimens with different x . The formation of solid solution (Mg1− x Co x )2 TiO4 ( x =0.02–0.1) was confirmed by the X-ray diffraction patterns, energy dispersive X-ray analysis, and the lattice parameters measured. By increasing x from 0 to 0.05, the Q × f of the specimen can be tremendously boosted from 150 000 GHz to a maximum of 286 000 GHz. A fine combination of microwave dielectric properties (ɛr ∼15.7, Q × f ∼286 000 GHz at 10.4 GHz, τf ∼−52.5 ppm/°C) was achieved for (Mg0.95 Co0.05 )2 TiO4 ceramics sintered at 1390°C for 4 h. Ilmenite-structured (Mg0.95 Co0.05 )TiO3 was detected as a second phase. The presence of the second phase would cause no significant variation in the dielectric properties of the specimen because it possesses compatible properties compared with that of the main phase. In addition, only a small deviation in the dielectric properties was monitored for specimens with x =0.04–0.05 at 1360°–1420°C. It not only provides a wide process window but also ensures an extremely reliable material proposed as a very promising dielectric for low-loss microwave and millimeter wave applications. 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.
Zong-Yang Shen Yuhua Zhen Ke Wang Jing-Feng Li 《Journal of the American Ceramic Society》2009,92(8):1748-1752
Microstructure characteristics, phase transition, and electrical properties of (Na0.535 K0.485 )0.926 Li0.074 (Nb0.942 Ta0.058 )O3 (NKN-LT) lead-free piezoelectric ceramics prepared by normal sintering are investigated with an emphasis on the influence of sintering temperature. Some abnormal coarse grains of 20–30 μm in diameter are formed in a matrix consisting of about 2 μm fine grains when the sintering temperature was relatively low (980°C). However, only normally grown grains were observed when the sintering temperature was increased to 1020°C. On the other hand, orthorhombic and tetragonal phases coexisted in the ceramics sintered at 980°–1000°C, whereas the tetragonal phase becomes dominant when sintered above 1020°C. For the ceramics sintered at 1000°C, the piezoelectric constant d 33 is enhanced to 276 pC/N, which is a high value for the Li- and Ta-modified (Na,K)NbO3 ceramics system. The other piezoelectric and ferroelectric properties are as follows: planar electromechanical coupling factor k p =46.2%, thickness electromechanical coupling factor k t =36%, mechanical quality factor Q m =18, remnant polarization P r =21.1 μC/cm2 , and coercive field E c =1.85 kV/mm. 相似文献
16.
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
17.
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
18.
Ritesh Rawal Antonio Feteira Alberto Arenas Flores Neil C. Hyatt Anthony R. West Derek C. Sinclair Kumaravinothan Sarma Neil McN. Alford 《Journal of the American Ceramic Society》2006,89(1):336-339
The dielectric properties of dense ceramics of the "twinned" 8H-hexagonal perovskite Ba8 Nb4 Ti3 O24 are reported. Single-phase powders were obtained from the mixed-oxide route at 1325°C and ceramics (>92% of the theoretical X-ray density) by sintering in air or flowing O2 at 1400°–1450°C. The ceramics are dc insulators with a band gap >3.4 eV that resonate at microwave frequencies with relative permittivity, ɛr ∼44–48, quality factor, Q × f r ∼21 000–23 500 GHz (at f r ∼5.5 GHz) and temperature coefficient of resonant frequency, TC f ,∼+115 ppm/K. 相似文献
19.
Jin-Rong Cheng Richard Eitel L. Eric Cross 《Journal of the American Ceramic Society》2003,86(12):2111-2115
(1 – x )(Bi0.8 La0.2 )(Ga0.05 Fe0.95 )O3 · x PbTiO3 (BLGF-PT) crystalline solutions have been fabricated by solid-state reactions. BLGF-PT has single perovskite phase structure with a rhombohedral–tetragonal (FEr -FEt ) morphotropic phase boundary (MPB) at a PT content of x = 0.43. Lanthanum substitution has been found to increase the insulation resistance and decrease the coercive field down to 20 kV/cm, which results in significant improvements in dielectric and piezoelectric properties of BLGF-PT. The dielectric constant, loss tangent, Curie temperature, remnant polarization, piezoelectric d 33 constant, and planar coupling factor of 1760, 0.05, 264°C, 33 μC/cm2 , 295 pC/N, and 0.36, respectively, have been achieved for BLFG-PT in the vicinity of the MPB. Compared with conventional Pb(Zr,Ti)O3 (PZT) piezoelectric ceramics, the BLGF-PT is a competitive alternative piezoelectric material with decreased lead content. 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