共查询到20条相似文献,搜索用时 625 毫秒
1.
通过对(1-x)(K0.5Na0.5)NbO3-xSrTiO3(0≤x≤0.15)陶瓷的相组成、晶体结构和介电性能的研究发现,该陶瓷为单一的钙钛矿结构相.当x含量较小(x<0.1)时为正交相结构,x≥0.1时转变为四方相结构.随着SrTiO3掺杂量的增加,样品的致密度增加,样品由正常铁电相逐渐向弥散铁电相转变,且相
关键词:
弛豫铁电体
0.5Na0.5)NbO3铁电陶瓷')" href="#">(K0.5Na0.5)NbO3铁电陶瓷
3掺杂')" href="#">SrTiO3掺杂
相变温度 相似文献
2.
采用了传统的固相烧结工艺,制备了不同Zr和Hf掺杂量的SrBi4Ti4-xZrxO15(x=000,003, 006,010,020)和SrBi4Ti4-xHfxO15(x=000,0005, 0015,0030,0060)的陶瓷
关键词:
4Ti4-xZrxO15')" href="#">SrBi4Ti4-xZrxO15
4Ti4-xHfxO15')" href="#">SrBi4Ti4-xHfxO15
铁电性能
介电性能 相似文献
3.
4.
5.
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
6.
7.
8.
利用固相反应法制备了Bi0.5Ca0.5Mn1-xCoxO3(0≤x≤0.12)系列多晶样品.研究了Co掺杂对Bi0.5Ca0.5MnO3电荷有序的影响.结果表明,Co掺杂导致电荷有序相逐渐融化、铁磁相互作用的增强;当x≥0.08时,电荷有序转变峰完全消失,但残留的反铁磁电荷有
关键词:
钙钛矿锰氧化物
电荷有序
团簇玻璃
相分离 相似文献
9.
利用固相反应烧结技术制备La0.1Bi0.9-xEuxFeO3系列化合物. 利用X射线粉末衍射进行物相鉴定和结构分析,确定了材料的相关系:x≤0.05,材料为R3c结构相;0.08≤x≤0.12,材料为赝R3c结构相;x≥0.15是Pbnm相,其中0.15≤x≤0.20区域Pbnm相存在畸变. 磁测量结果表明,材料具有弱铁磁性,对于x≤0.20材料,磁矩在x=0.12成分存在极值. 利用阻抗分析仪测量了室温介电常数随成分的变化关系.讨论了材料的结构与弱铁磁性和室温介电常数间的关系.
关键词:
0.1Bi0.9-xEuxFeO3')" href="#">La0.1Bi0.9-xEuxFeO3
X射线衍射
磁性
介电常数 相似文献
10.
用溶胶-凝胶法制备1.0%mol Mn,Cr,Co掺杂 BaTiO3(BTO)粉体,在1350℃下烧结成多晶陶瓷样品.X射线衍射和差示扫描量热分析表明,室温下掺杂BaTiO3具有四方钙钛矿结构;居里点和相变潜热随Cr,Mn,Co掺杂逐渐降低.将掺杂BaTiO3与Tb1-xDyxFe2-y(TDF)胶合制成双层磁电复合材料,并研究了Cr:BTO-TDF,Mn∶BTO-TDF,Co:BTO-TDF层状复合材料中的磁电效应.实验表明,在340×80 A·m-1偏置磁场下, Cr:BTO-TDF的横向磁电电压系数达到最大值586 mV·cm-1·(80 A·m-1)-1.在400×80 A·m-1偏置磁场下,Mn∶BTO-TDF和Co:BTO-TDF的横向磁电电压系数的最大值分别为480 mV·cm-1·(80 A·m-1)-1和445mV·cm-1·(80 A·m-1)-1.研究表明掺杂BaTiO3-TDF层状复合材料中具有较强的磁电耦合.作为无铅压电材料,掺杂BaTiO3制备的磁电效应器件颇具应用前景.
关键词:
磁电效应
双层复合材料
3')" href="#">掺杂BaTiO3
1-xDyxFe2-y')" href="#">Tb1-xDyxFe2-y 相似文献
11.
Effects of A-site non-stoichiometry on the structural and electrical properties of 0.96K0.5Na0.5NbO3- 0.04LiSbO3 lead-free piezoelectric ceramics 下载免费PDF全文
Effects of A-site non-stoichiometry on the structural and electrical properties of 0.96K0.5+xNa0.5+xNbO3- 0.04LiSbO3 lead-free piezoelectric ceramics were examined for 0 ≤ x ≤ 0.02. The piezoelectric coefficients exhibited a maximum, d33 = 187 pC/N at x = 0.0075, coinciding with the maximum of the grain size and the apparent density at x = 0.0075. The apparent density and the piezoelectric coefficients decreased with increasing x at higher x which was likely due to the crystal geometrical distortion of 0.96K0.5+xNa0.5+xNbO3-0.04LiSbO3. In addition, super-large grains were found and this may be due to liquid phase sintering. Excess (K++Na+) attracted a sum of space charges to keep the charge neutral, resulting in charge leakage during the course of ceramic polarization, influencing the piezoelectric and ferroelectric properties. These findings are of importance for guiding the design of K0.5Na0.5NbO3-based lead-free ceramics with enhanced electrical properties. 相似文献
12.
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
13.
Lead-free multi-component ceramics (Bi1−x−yNa0.925−x−yLi0.075)0.5BaxSryTiO3 have been prepared by an ordinary sintering technique and their structure and electrical properties have been studied. All the ceramics can be well-sintered at 1100 °C. X-ray diffraction patterns shows that Li+, Ba2+ and Sr2+ diffuse into the Bi0.5Na0.5TiO3 lattices to form a new solid solution with a pure perovskite structure, and a morphotropic phase boundary (MPB) is formed at 0.04 < x < 0.08. As compared to pure Bi0.5Na0.5TiO3 ceramic, the coercive field EC of the ceramics decreases greatly and the remanent polarization Pr of the ceramics increases significantly after the formation of the multi-component solid solution. Due to the MPB, lower EC and higher Pr, the piezoelectricity of the ceramics is greatly improved. For the ceramics with the compositions near the MPB (x = 0.04–0.08 and y = 0.02–0.04), piezoelectric coefficient d33 = 133–193 pC/N and planar electromechanical coupling factor kP = 16.2–32.1%. The depolarization temperature Td reaches a minimum value near the MPB. The temperature dependences of the ferroelectric and dielectric properties suggest that the ceramics may contain both the polar and non-polar regions at temperatures near/above Td. 相似文献
14.
The microwave dielectric properties of La1-xBx(Mg0.5Sn0.5)O3 ceramics were examined with a view to their exploitation for mobile communication. The La1-xBx(Mg0.5Sn0.5)O3 ceramics were prepared by the conventional solid-state method with various sintering temperatures. The X-ray diffraction patterns of the La0.995B0.005(Mg0.5Sn0.5)O3 ceramics revealed no significant variation of phase with sintering temperatures. A maximum apparent density of 6.58 g/cm3, a dielectric constant (εr) of 19.8, a quality factor (Q × f) of 41,800 GHz, and a temperature coefficient of resonant frequency (τf) of −86 ppm/°C were obtained for La0.995B0.005(Mg0.5Sn0.5)O3 ceramics that were sintered at 1500 °C for 4 h. 相似文献
15.
In this study, monophasic Bax(Na0.5Bi0.5)1−xBi4Ti4O15 (x=0.03, 0.06, 0.09 and 0.12) ceramics fabricated from the powders synthesized via the solid-state reaction route exhibited relaxor behavior. X-ray diffraction analysis revealed that the barium-modified Na0.5Bi4.5Ti4O15 ceramics have a pure four-layer Aurivillius phase structure. Dielectric properties and phase transitions were studied and are explained in terms of lattice response of these ceramics. A shift in ferroelectric–paraelectric phase transition (Tc) to lower temperatures and a corresponding increase in permittivity peak with increasing concentration of Ba2+ are also observed. The decrease of orthorhombicity in the lattice structure by the larger Ba2+ ion incorporation, indicating an approach of a and b parameters, results in lower Curie temperature. The piezoelectric activity of Na0.5Bi4.5Ti4O15 (NBT) ceramics was significantly improved by the modification of barium. The Curie temperature Tc and piezoelectric coefficient d33 for the composition with x=0.12 were found to be 635 °C and 21 pC/N, respectively. The relationship of polarization with lattice response is discussed. 相似文献
16.
In this article, we report successful preparation of dense [(Na0.5K0.5)1−xSrx](Nb1−xTix)O3 (x=0.005-0.100) ceramics by ordinary sintering in air. The dependence of phase structure on doping content of SrO and TiO2 has been determined by the X-ray diffraction technique. It was found that the crystal structure changed from orthorhombic to tetragonal at x≈0.040. Dielectric study revealed that the dielectric relaxor behavior was induced by doping of SrO and TiO2 into (Na0.5K0.5)NbO3. The samples in the composition range from x=0.005 to 0.020 exhibited excellent electrical properties, piezoelectric constant of electromechanical planar and thickness coupling coefficients of kp=26.6-32.5% and kt=39.8-43.8%. The results show that the [(Na0.5K0.5)1−xSrx](Nb1−xTix)O3 ceramics are one of the promising lead-free materials for electromechanical transducer applications. 相似文献
17.
K.S. LeeJ.H. Yoo 《Current Applied Physics》2012,12(3):798-802
In the study, in order to develop the lead-free piezoelectric ceramics for actuator, transformer and other electronic-devices application, (K0.5Na0.5)(Nb0.9+xTa0.1)O3 + 0.5 mol% CuO + 0.2 mol% MnO2 ceramics were prepared by conventional mixed oxide method. The effects of B-site non-stoichiometry in [(K0.5Na0.5)] [(Nb0.9+xTa0.1)O3] ceramics on microstructure and piezoelectric properties were investigated. The density, electromechanical coupling factor (kp), mechanical quality factor (Qm), piezoelectric constant (d33), TC and TO-T of NKNT ceramics with x = 0.0065 showed the optimum values of 4.58 g/cm3, 0.427, 1554, 109 pC/N, 373 °C and 226 °C, respectively, suitable for piezoelectric motor, and transformer applications. 相似文献
18.
19.
Lead-free piezoelectric ceramics of (1−x)K0.5Na0.5NbO3-xLiTaO3 (KNN-LT) system have been investigated in this work. X-ray diffraction, Raman spectra measurements, DSC (Differential Scanning Calorimetric), and dielectric constant versus temperature provide direct evidence that the phase transition temperature between tetragonal and orthorhombic shift to lower temperature with the increasing of LT content. The KNN-0.05LT ceramics exhibit the highest high-field d33 up to 220 pm/V. At the same time, we also investigated the relationship between phase structure and electric properties, showing that the orthorhombic phase presents better piezoelectric temperature stabilities than the tetragonal phase. The result may provide a new way for KNN-based lead-free ceramics. 相似文献
20.
Lead-free (Na0.5K0.5)NbO3-based piezoelectric ceramics were successfully fabricated by substituting with a small amount of BiFeO3 (BF). Difficulty in sintering of pure NKN ceramics can be eased by adding a few molar percent of BF, and the crystalline structure is also changed, leading to a morphotropic phase boundary (MPB) between ferroelectric orthorhombic and rhombohedral phases. The MPB exists near the 1-2 mol% BF-substituted NKN compositions, exhibiting enhanced ferroelectric, piezoelectric, and electromechanical properties of Pr=23.3 μC/cm2, d33=185 pC/N, and kp=46%, compared to an ordinarily sintered pure NKN ceramics. The MPB composition has a Curie temperature of ∼370 °C, comparable to that of some commercial PZT materials. 相似文献