共查询到19条相似文献,搜索用时 140 毫秒
1.
Dunmin Lin Qiaoji Zheng Chenggang Xu K. W. Kwok 《Applied Physics A: Materials Science & Processing》2008,93(2):549-558
(1−x−y)Bi0.5Na0.5TiO3–xBi0.5K0.5TiO3– yBi0.5Li0.5TiO3 lead-free piezoelectric ceramics have been prepared by an ordinary sintering technique, and their structure, electrical properties,
and temperature characteristics have been studied systematically. The ceramics can be well-sintered at 1050–1150 °C. The increase
in K+ concentration decreases the grain-growth rate and promotes the formation of grains with a cubic shape, while the addition
of Li+ decreases greatly the sintering temperature and assists in the densification of BNT-based ceramics. The results of XRD diffraction
show that K+ and Li+ diffuse into the Bi0.5Na0.5TiO3 lattices to form a solid solution with a pure perovskite structure. As x increases from 0.05 to 0.50, the ceramics transform gradually from rhombohedral phase to tetragonal phase and consequently
a morphotropic phase boundary (MPB) is formed at 0.15≤x≤0.25. The concentration y of Li+ has no obvious influence on the crystal structure of the ceramics. Compared with pure Bi0.5Na0.5TiO3, the partial substitution of K+ and Li+ for Na+ lowers greatly the coercive field E
c and increases the remanent polarization P
r of the ceramics. Because of the MPB, lower E
c and large P
r, the piezoelectricity of the ceramics is improved significantly. For the ceramics with the compositions near the MPB (x=0.15–0.25 and y=0.05–0.10), the piezoelectric properties become optimum: piezoelectric coefficient d
33=147–231 pC/N and planar electromechanical coupling factor k
P=20.2–41.0%. In addition, the ceramics exhibit relaxor characteristic, which probably results from the cation disordering
in the 12-fold coordination sites. The depolarization temperature T
d shows a strong dependence on the concentration x of K+ and reaches the lowest values at the MPB. The temperature dependences of the ferroelectric and dielectric properties at high
temperatures may imply that the ceramics may contain both the polar and non-polar regions at temperatures above T
d. 相似文献
2.
3.
采用固相合成工艺,制备了Bi05Ba05Fe05Ti049Nb001O3(BBFTN)热敏陶瓷,借助X射线衍射仪、扫描电子显微镜、阻温测试仪和交流阻抗谱考察其微结构、直流电阻、介电特性、阻抗和电学模量方面的电学性能. 结果表明:BBFTN材料依然为立方钙钛矿结构,平均晶粒尺寸约为10 μm,晶格常数相对于BaTiO3的晶格常数有所变大;室温电
关键词:
05Ba05Fe05Ti049Nb001O3')" href="#">Bi05Ba05Fe05Ti049Nb001O3
微结构
电学性能 相似文献
4.
以传统的固相反应法制备了Bi0.5Ba0.5FeO3陶瓷,并采用X射线衍射仪、扫描电子显微镜、直流阻温测试仪和交流阻抗分析仪测试了Bi0.5Ba0.5FeO3陶瓷的微结构和电性能.分析结果表明:Bi0.5Ba0.5FeO3陶瓷具有立方钙钛矿结构,颗粒尺寸约1.0 μm;在16—280 ℃范围内,Bi0.5Ba0.5FeO3陶瓷表现出明显的负温度系数热敏效应,其热敏常数、活化能分别为6490 K及0.558 eV;介电温谱揭示,在280 ℃下Bi0.5Ba0.5FeO3陶瓷材料没有出现相变行为.对于交流阻抗谱,采用3个串联的RQ(R与Q为并联)等效部件来拟合分析,拟合结果表明拟合数据与实验数据高度匹配,且这3个等效部件分别代表晶界、晶粒和晶壳的贡献.3个部件中,晶粒对陶瓷电阻阻值的影响最大,晶壳贡献次之,晶界最小,且3个部件电阻值都显示出负温度系数效应.在25—115 ℃范围内,电学模量虚部峰频与阻抗虚部峰频始终不匹配,意味着Bi0.5Ba0.5FeO3陶瓷体内部一直表现出局域导电机理.
关键词:
0.5Ba0.5FeO3陶瓷')" href="#">Bi0.5Ba0.5FeO3陶瓷
电性能
阻抗分析 相似文献
5.
BaFCl0.5Br0.5:Sm2+的荧光特性分析 总被引:4,自引:2,他引:2
本文是对无机光谱烧孔的典型材料BaFCl0.5Br0.5:Sm2+的发光动力学过程进行的探索。通过实验得到了5D2、5D1、5D0→7F0的荧光强度、荧光衰减曲线随温度的变化关系,对5D2→4f5d带的热激活、5DJ间的无辐射弛豫,5DJ→7F0的辐射跃迁等过程进行了分析。 相似文献
7.
利用脉冲激光制膜法,在多种衬底和温度条件下,系统研究了La0.5Sr0.5CoO3(LSCO)薄膜的结构和外延生长特性,在LaAlO3,SrTiO3和MgO衬底上实现了LSCO薄膜的外延生长.外延生长的薄膜具有低的电阻率和金属性导电特征.研究表明,外延生长的最佳温度范围为700—800℃,最佳衬底为LaAlO3.并着重探讨了衬底材料和淀积温度等多种因素对LSCO薄膜的生长与性
关键词: 相似文献
8.
用扫描隧道显微镜/谱仪仔细研究了铁基超导单晶FeSe0.5Te0.5样品的表面形貌和隧道谱, 测量到了清晰的表面原子形貌和在空间比较稳定的隧道谱结构.在样品中测量的隧道谱零能态密度比较高, 说明样品里面有比较强的非弹性准粒子散射. 在正能5 mV附近有个较大的背景鼓包, 这一背景在很高温度也未消失. 空间中Se和Te集中的位置会带来高能背景的变化, 超导能隙附近谱的形状大致相同. 较强的非弹性准粒子散射破坏了超导的准粒子散射, 因此没有在二维微分电导图中发现超导准粒子相干散射的特征亮斑. 相似文献
9.
在0—7GPa静压范围内测量了自发有序Ga0.5In0.5P合金的室温光致发光谱.三块样品的常压带隙能量分别比无序样品低115,92和43meV,它们的压力系数也从无序样品的92meV/GPa分别减小到75,81和83meV/GPa.用Γ-L相互作用模型可以同时解释有序合金的带隙能量的降低以及压力系数的减小.得到的Γ-L相互作用势分别为0.19,0.15和0.10eV.表明在自发有序Ga0.5In0.5P合金中存在着的 相似文献
10.
11.
Chang Won AhnSung Sik Won Aman UllahSun Young Lee Su Dae LeeJi Hye Lee William JoIll Won Kim 《Current Applied Physics》2012,12(3):903-907
0.85Bi0.5Na0.5TiO3-0.15Bi0.5K0.5TiO3 (BNKT15) lead-free thin films were prepared on Pt(111)/TiO2/SiO2/Si(100) substrates by the chemical solution deposition method. BNKT15 are MPB composition in the Bi0.5Na0.5TiO3-Bi0.5K0.5TiO3 (BNT-BKT) system. The maximum piezoelectric coefficient (d33,f) value of BNKT15 thin film is approximately 75 pm/V, which is comparable to that of polycrystalline PZT thin films. These results suggest that BNKT15 thin film can be used as an alternative for PZT films in piezoelectric micro-electromechanical systems. 相似文献
12.
用固相反应法制备了Na0.25K0.25Bi0.5TiO3 (NKBT50)陶瓷,研究了该陶瓷在室温至400℃温度范围内的介电性能.发现该陶瓷的介电温谱与烧结气氛、极化状态有关.在空气中烧结的未极化样品在70℃附近存在介电和损耗峰,而极化后及在氧气氛中烧结的样品并不存在该介电、损耗峰.分析认为70℃的介电和损耗峰与氧空位形成的缺陷偶极子的极化弛豫有关.热激电流显示,陶瓷的去极化温度为225℃,与此相对应的介电、损耗峰也
关键词:
介电性能
氧空位
极化弛豫
钛酸铋钠钾 相似文献
13.
Vacancy-induced magnetism in perovskite SrTiO3 is investigated by ab initio calculations and magnetic measurements. The calculations of the generalized gradient approximation (GGA), the local density approximation (LDA) and the local density approximation with on-site effect U (LDA+U) methods show that stoichiometric SrTiO3 is nonmagnetic. The GGA calculated results indicate that Ti or O vacancy could induce magnetism rather than Sr vacancy. The LDA and LDA+U calculations show that the Ti vacancy could induce magnetism, while Sr and O vacancies couldn't. The experimental results confirm that SrTiO3 nanocrystalline powders exhibit room-temperature ferromagnetism (FM) and the magnetic moment results from cation vacancies. 相似文献
14.
Site occupation of doping La3+ cations and phase transition in Na0.5Bi0.5TiO3–BaTiO3 solid solution 下载免费PDF全文
The effects of La doping on the ferroelectric properties of 0.92Na0.5Bi0.5TiO3-0.08BaTiO3(NBT-BT) solid solution have been studied both experimentally and theoretically.The experimental results show that an abnormal ferro-toantiferroelectric phase transition is induced by La doping in NBT-BT.The first-principles calculations indicate that La3+ cations selectively substitute for the A site in NBT-BT as donors.Furthermore,the computed binding energy reveals that La cations is most likely to substitute Ba 2+or Na+,not Bi3+,at A site as donors in NBT-BT,as supported by our Raman spectra.The ferro-to-antiferroelectric phase transition of La-doped NBT-BT is believed to originate from the lattice aberrance and redistribution of valence electrons,thus strengthening the bonding of A-O,enhancing the hybridization between the A cation d orbital and O 2p orbital,and resulting in the deflection of the polar direction of NBT-BT lattice. 相似文献
15.
(Na0.85K0.15)0.5Bi0.5TiO3 thin films were deposited on LaNiO3(LNO)/SiO2/Si(1 0 0) and Pt/Ti/SiO2/Si(1 0 0) substrates by metal-organic decomposition, and the effects of bottom electrodes LNO and Pt on the ferroelectric, dielectric and piezoelectric properties were investigated by ferroelectric tester, impedance analyzer and scanning probe microscopy, respectively. For the thin films deposited on LNO and Pt electrodes, the remnant polarization 2Pr are about 22.6 and 8.8 μC/cm2 under 375 kV/cm, the dielectric constants 238 and 579 at 10 kHz, the dielectric losses 0.06 and 0.30 at 10 kHz, the statistic d33eff values 95 and 81 pm/V. The improved piezoelectric properties could make (Na1−xKx)0.5Bi0.5TiO3 thin film as a promising candidate for piezoelectric thin film devices. 相似文献
16.
BaTiO3–Bi0.5Na0.5TiO3 is one of the promising candidates as a high-temperature relaxor with a high Curie temperature and several preferred dielectric characteristics. It has been found experimentally for a long time that adding calcium to BaTiO3–Bi0.5Na0.5TiO3 improves its temperature characteristic of the capacitance [J. Electron. Mater. 39, 2471]. In this study, Calcium (Ca) defects in perovskite BaTiO3 and Bi0.5Na0.5TiO3 have been studied based on first-principles calculations. In both BaTiO3 and Bi0.5Na0.5TiO3, our calculations showed that Ca atom energetically prefers to substitute for the cations, that is Ba, Bi, Na and Ti, depending on the growth conditions. In most cases, Ca predominantly substitutes on the A-site without providing additional electrical carriers (serve as either neutral defects or self-compensating defects). The growth conditions where Ca can be forced to substitute for B-site (with limited amount) and the conditions where Ca can be forced to serve as an acceptor are identified. Details of the local structures, formation energies and electronic properties of these Ca defects are reported. 相似文献
17.
The difficulties in synthesizing phase pure BaTiO3 doped-(Na0.5Bi0.5)TiO3 are known. In this work, we reporting the optimized pulsed laser deposition (PLD) conditions for obtaining pure phase 0.92(Na0.5Bi0.5)TiO3-0.08BaTiO3, (BNT-BT0.08), thin films. Dielectric, ferroelectric and piezoelectric properties of BNT-BT0.08, thin films deposited by PLD on Pt/TiO2/SiO2/Si substrates are investigated in this paper. Perovskite structure of BNT-BT0.08 thin films with random orientation of nanocrystallites has been obtained by deposition at 600 °C. The relative dielectric constant and loss tangent at 100 kHz, of BNT-BT0.08 thin film with 530 nm thickness, were 820 and 0.13, respectively. Ferroelectric hysteresis measurements indicated a remnant polarization value of 22 μC/cm2 and a coercive field of 120 kV/cm. The piezoresponse force microscopy (PFM) data showed that most of the grains seem to be constituted of single ferroelectric domain. The as-deposited BNT-BT0.08 thin film is ferroelectric at the nanoscale level and piezoelectric. 相似文献
18.
Yanjie ZhangRuiqing Chu Zhijun XuQian Chen Yong LiuGuangchao Zhang 《Current Applied Physics》2012,12(1):204-209
(Bi0.5Na0.5)0.94Ba0.06TiO3 ceramics doped with Li2CO3 and Bi2O3 as sintering aids were manufactured, and their micro structural, dielectric and piezoelectric properties were investigated. All specimens could be well sintered at a low-temperature of 1080 °C. The bulk density of the specimens doped with a small amount of Li2CO3 was enhanced. The dielectric and piezoelectric properties of ceramics were investigated with different amounts of Li2CO3 substitutions. High electrical properties of d33 = 167 pC/N, kp = 0.34, Pr = 40 μC/cm2 and Ec = 38 kV/cm were obtained from the specimen containing 0.1 mol% of Li2CO3 sintered at 1080 °C. 相似文献
19.
Yiping Guo Ken-ichi Kakimoto Hitoshi Ohsato 《Journal of Physics and Chemistry of Solids》2004,65(11):1831-1835
We report that ferroelectric-relaxor behavior is induced by doping of SrO and TiO2, or BaO and TiO2 into classic ferroelectric (Na0.5K0.5)NbO3. It is found that [(Na0.5K0.5)0.9Sr0.1](Nb0.9Ti0.1)O3 ceramics exhibit a pronounced ferroelectric-relaxor behavior, comparable to that of [(Na0.5K0.5)0.9Ba0.1](Nb0.9Ti0.1)O3 ceramics. Our results indicate that the relaxor behavior is closely related to the appearance of micropolar regions in these systems. The relaxor behavior should arise from the dynamic response of micropolar clusters. Raman spectra of [(Na0.5K0.5)1−xSrx](Nb1−xTix)O3 ceramics measured in the wavenumber range from 100 to 1200 cm−1 confirm that the first order scattering is dominant in phonon bands should result from both short-range ordered region (micropolar regions) and disordered matrix. The frequency dependence of dielectric permittivity measurements show that the relaxor behavior of SrO and TiO2, or BaO and TiO2 doped (Na0.5K0.5)NbO3 ceramics is not a Debye type in the radio frequency range. 相似文献