非化学计量和掺杂对(Na1/2Bi1/2)0.92Ba0.08TiO3陶瓷电性能的影响

研究了非化学计量和掺杂对无铅压电陶瓷(Na_1/2Bi_1/2)_0.92Ba_0.08TiO₃的压电性能及去极化温度的影响.研究发现A位非化学计量可以提高陶瓷的压电性能;B位掺杂对材料电学性能的影响规律类似于Pb(Ti,Zr)O₃系压电陶瓷的相关规律;由于非化学计量和掺杂会影响到A位离子对B位离子与氧离子形成的BO₆八面体的耦合作用,影响到畴的稳定性,从而影响 关键词： 无铅压电陶瓷 非化学计量 掺杂 电性能     

锰掺杂对Ba(Zr,Ti)O3陶瓷压电与介电性能的影响

采用氧化物固相反应法制备了锰掺杂改性的Ba(Zr_0.06Ti_0.94)O₃陶瓷.研究了锰的掺杂量对Ba(Zr_0.06Ti_0.94)Mn_xO₃ (BZTM)陶瓷的结构、介电和压电性能的影响.实验发现,当锰含量x<0.5 mol%时进入晶格,使材料压电性能提高,损耗减小,表现出受主掺杂的特性;当锰含量x>0.5 mo 关键词： Ba(Zr 3 陶瓷')" href="#">Ti)O₃ 陶瓷 锰掺杂 介电性能 压电性能     

La0.3Sr0.7TiO3模板层对Pb(Zr0.5Ti0.5)O3薄膜的铁电性能增强效应的研究

通过sol-gel法在Si (111) 基片上分别制备了LaNiO₃(LNO)底电极和LaNiO₃/La_0.3Sr_0.7TiO₃ (LNO/LSTO)底电极.然后采用sol-gel 方法，在两种衬底上分别制备了Pb (Zr_0.5Ti_0.5)O₃ (PZT)铁电薄膜.XRD分析表明，两种PZT薄膜均具有钙钛矿结构，且在LNO底电极上的PZT薄膜呈(100) 择优取向，而在LNO/LSTO底电极上的PZT薄膜呈随机取向.铁电性能测试表明，相对LNO衬底上制备的PZT薄膜，在LNO/LSTO底电极上制备的PZT薄膜的剩余极化强度得到了有效的增强，同时矫顽场也增大.介电常数和漏电流的测试表明，LNO/LSTO底电极上制备的PZT薄膜具有大的介电常数和漏电流. 关键词： PZT薄膜 铁电性 漏电流 0.3Sr_0.7TiO₃')" href="#">La_0.3Sr_0.7TiO₃     

0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3单晶/环氧树脂1-3型复合材料的压电性能研究

模拟了0.7Pb(Mg_1/3Nb_2/3)O₃-0.3PbTiO₃(PMN-0.3PT)单晶1-3型压电复合材料的性能与单晶体积分数的关系,得出性能最优时压电相的体积分数为64%, 在这一体积分数下,采用切割-填充法,并使用了不同类型的环氧树脂填充制备复合材料.系统地研究了聚合物相对复合材料性能的影响,研究表明,减小聚合物相的刚度系数c和密度ρ有利于提高复合材料的性能,且聚合物相与压电相的结合强度对性能的影响非常明显,制备的PMN-0.3 PT单晶1-3型复合材料的厚度伸缩机电耦合系数k_t高达90.1%,压电系数d₃₃大于1000pC/N,机械品质因数Q_m为10.39,声阻抗Z也大大降低,性能明显优于传统的Pb(Zr_xTi_1-x)O₃(PZT)陶瓷及其1-3复合材料,在压电换能器和传感器中显示出广阔的前景. 关键词： PMN-PT单晶 压电复合材料 压电相 聚合物相     

(1-x)(K0.5Na0.5)NbO3-xSrTiO3陶瓷的弛豫铁电性能

通过对（1-x）（K_0.5Na_0.5）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 0.5Na_0.5）NbO₃铁电陶瓷')" href="#">（K_0.5Na_0.5）NbO₃铁电陶瓷 3掺杂')" href="#">SrTiO₃掺杂 相变温度     

La诱导(Pb(1-3x/2)Lax)(Zr0.5Sn0.3Ti0.2)O3反铁电介电弛豫研究

采用标准电子陶瓷工艺制备了(Pb_(1-3x/2)La_x)(Zr_0.5Sn_0.3Ti_0.2)O₃(PLZST,0.00≤x≤0.18)反铁电陶瓷,利用X射线衍射、不同频率下弱场介电温谱、强场下的极化强度-电场(P-E)测试研究了材料相结构和电学性能.实验结果发现,随La含量x增大,室温下材料由铁电三方相(关键词： 反铁电陶瓷 介电频率色散 相变弥散 介电弛豫     

探索基于人工超晶格LaFeO3-YMnO3和自然超晶格n-LaFeO3-Bi4Ti3O12薄膜多铁性

基于纳米尺寸下复合铁电材料和反铁磁性材料是一个探索多铁性材料有效的方法. 利用激光脉冲沉积制备出LaFeO₃-YMnO₃人工超晶格和掺入不同层LaFeO₃, BiFeO₃的Bi₄Ti₃O₁₂的外延薄膜. 通过系统的X射线衍射、透射电子显微术、扫描透射电子显微术下的能量损失谱表征证明这些样品具有原子尺寸上清晰的界面和完整的层状结构. 磁性测试证明这些材料具有亚铁磁性. 特别是在0.5和1.5LaFeO₃-Bi₄Ti₃O₁₂中的亚铁磁性甚至能保持到室温. 就铁电性而言, 铁电性测试显示出LaFeO₃-YMnO₃和插入BiFeO₃的Bi₄Ti₃O₁₂样品中存在较大的漏电流, 而在0.5LaFeO₃-Bi₄Ti₃O₁₂样品中存在铁电性. 因此在0.5LaFeO₃-Bi₄Ti₃O₁₂中能够实现亚铁磁和铁电共存. 其次发现当掺入多层的钙钛矿(3层SrTiO₃或2.5层LaFeO₃)后, Bi₄Ti₃O₁₂ 的层状结构将出现结构失稳现象. 这些工作对于利用纳米复合开发新颖多铁性提供一些实例.     

K0.5Na0.5NbO3-LiSbO3-BiFeO3/CuFe2O4复合陶瓷的制备与磁电性能研究

采用传统的固相法制备了(1-x)(K_0.5Na_0.5NbO₃-LiSbO₃-BiFeO₃)-xCuFe₂O₄ (x=0.1, 0.2, 0.3, 0.4) 磁电复合陶瓷, 并借助X射线衍射仪、扫描电镜和磁电耦合系数测试仪等对复合陶瓷的微结构和性能进行了分析. 结果表明, 复合陶瓷的K_0.5Na_0.5NbO₃-LiSbO₃-BiFeO₃和CuFe₂O₄物相之间发生了一定的离子相互扩散作用, 且两相的颗粒大小匹配性较好. 随着CuFe₂O₄含量增加, 复合陶瓷的压电系数从130 pC/N减小到30 pC/N, 饱和磁致伸缩系数从4.5×10^-6增加到12.4×10^-6左右, 磁电耦合系数表现出先增加后减小, 在x=0.3时获得最大的磁电耦合系数9.4 mV·cm^-1·Oe^-1. 关键词： 0.5Na_0.5NbO₃-LiSbO₃-BiFeO₃')" href="#">K_0.5Na_0.5NbO₃-LiSbO₃-BiFeO₃ 2O₄')" href="#">CuFe₂O₄ 磁电耦合     

La0.5Sr0.5CoO3薄膜的外延生长及其机理研究

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La_0.5Sr_0.5CoO₃(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：     

Bi0.5Ba0.5FeO3 陶瓷的电性能及阻抗分析

以传统的固相反应法制备了Bi_0.5Ba_0.5FeO₃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Bi_0.5Ba_0.5FeO₃陶瓷的微结构和电性能.分析结果表明:Bi_0.5Ba_0.5FeO₃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,Bi_0.5Ba_0.5FeO₃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Bi_0.5Ba_0.5FeO₃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Bi_0.5Ba_0.5FeO₃陶瓷体内部一直表现出局域导电机理. 关键词： 0.5Ba_0.5FeO₃陶瓷')" href="#">Bi_0.5Ba_0.5FeO₃陶瓷 电性能 阻抗分析     

Relationship between phase structure and electrical properties of (K0.5Na0.5)NbO3-LiTaO3 lead-free ceramics

Lead-free piezoelectric ceramics of (1−x)K_0.5Na_0.5NbO₃-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.     

Properties of non-stoichiometric 0.935(K0.5+xNa0.5+x)NbO3-0.065LiSbO3 lead-free piezoelectric ceramics

0.935(K_0.5+xNa_0.5+x)NbO₃-0.065LiSbO₃ lead-free piezoelectric ceramics were prepared by normal sintering, and their piezoelectric and dielectric properties were investigated by varying the compensating amount x of alkaline elements (Na and K) addition. It was found that the crystal structure changed from tetragonal to orthorhombic with increasing x from −0.010 to 0.010. An MPB was tailored by optimizing the alkaline elements contents. Enhanced electrical and electromechanical responses of d₃₃=253 pC/N, k_p=0.47, k_t=0.45 and tanδ=0.027 were obtained in the ceramics with x=0.005. These excellent piezoelectric and electromechanical properties indicate that this system may be an attractive lead-free material for a wide range of electro-mechanical transducer applications.     

Large piezoresponse of lead-free Bi0.5(Na0.85K0.15)0.5TiO3 thin film

0.85Bi_0.5Na_0.5TiO₃-0.15Bi_0.5K_0.5TiO₃ (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 Bi_0.5Na_0.5TiO₃-Bi_0.5K_0.5TiO₃ (BNT-BKT) system. The maximum piezoelectric coefficient (d_33,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.     

A位等价与非等价取代对(K0.5Na0.5)NbO3陶瓷极化的影响

研究了在铌酸钾钠基陶瓷中,A位等价与非等价取代对陶瓷极化温度和极化电场的影响,结果表明:A位等价取代的陶瓷对极化温度和极化电场没有强烈依赖性,可以使极化足够充分,能有效提高铌酸钾钠基陶瓷的压电性能;相反,A位非等价取代的陶瓷对极化温度和极化电场敏感,容易击穿,极化不充分,限制了铌酸钾钠基陶瓷的压电性能. 关键词： 铌酸钾钠 极化 压电     

Microstructure and piezoelectric properties of Bi0.5(Na0.82K0.18)0.5TiO3−NaSbO3 ceramics

Lead-free piezoelectric ceramics (1−x)Bi_0.5(Na_0.82K_0.18)_0.5TiO₃−xNaSbO₃ have been prepared by a conventional ceramics technique, and their microstructure and electrical properties have been investigated. The addition of NaSbO₃ has no remarkable effect on the crystal structure within the studied doping content; however, an obvious change in microstructure took place. With increase in NaSbO₃ content, the temperature from a ferroelectric to antiferroelectric phase transition increases, and the temperature for a transition from antiferroelectric phases to paraelectric phases changes insignificantly. Simultaneously, the temperature range between the rhombohedral phase transition point and the Curie temperature point becomes smaller. The piezoelectric properties significantly increase with increase in NaSbO₃ content and the piezoelectric constant and electromechanical coupling factor attain maximum values of d₃₃=160 pC/N and k_p=0.333 at x=0.01. The results indicate that (1−x)Bi_0.5(Na_0.82K_0.18)_0.5TiO₃−xNaSbO₃ ceramic is a promising lead-free piezoelectric candidate material.     

Dielectric and piezoelectric properties of non-stoichiometric (K0.5Na0.5)(Nb0.9+xTa0.1)O3 ceramics

In the study, in order to develop the lead-free piezoelectric ceramics for actuator, transformer and other electronic-devices application, (K_0.5Na_0.5)(Nb_0.9+xTa_0.1)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 [(K_0.5Na_0.5)] [(Nb_0.9+xTa_0.1)O₃] ceramics on microstructure and piezoelectric properties were investigated. The density, electromechanical coupling factor (k_p), mechanical quality factor (Q_m), piezoelectric constant (d₃₃), T_C and T_O-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.     

Anisotropic electrical properties of Bi0.5(Na0.75K0.25)0.5TiO3 ceramics fabricated by reactive templated grain growth (RTGG)

We have fabricated lead-free Bi_0.5(Na_0.75K_0.25)_0.5TiO₃ (BNKT) ceramics by a conventional process (CP) and reactive templated grain growth (RTGG) methods. The effect of grain orientation on structure, dielectric, complex impedance and electrical properties was investigated. The phase formation and grain morphology of BNKT ceramics were examined by X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. High dielectric constant and low dielectric loss was observed for grain oriented (textured) BNKT ceramics. Complex impedance, temperature dependent ac and dc conductivity were performed to explore the conduction behavior of the prepared BNKT ceramics.     

Effects of A-site non-stoichiometry on the structural and electrical properties of 0.96K0.5Na0.5NbO3- 0.04LiSbO3 lead-free piezoelectric ceramics

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.     

Characterization of lead free (K0.5Na0.5)NbO3-LiSbO3 piezoceramic

(K_0.5Na_0.5)NbO₃ (KNN) based lead free ceramics have been fabricated by a solid state reaction. In this work, LiSbO₃ (LS) modified KNN based ceramics were sintered at atmospheric pressure and high density (>96% theoretical) was obtained. The detailed elastic, dielectric, piezoelectric and electromechanical properties were characterized by using the resonance technique combined with the ultrasonic method. The full set of material constants for the obtained polycrystalline ceramics were determined and compared to the pure hot pressed KNN counterpart. KNN-LS polycrystalline ceramic was found to have higher elastic compliance, dielectric permittivity and piezoelectric strain coefficients, but lower mechanical quality factor, when compared to pure KNN, exhibiting a “softening” behavior. However, a high coercive field (∼17 kV/cm) was found for the LS modified KNN material. The properties as a function of temperature were determined in the range of −50-250 ^°C, showing a polymorphic phase transition near room temperature, giving rise to improved piezoelectric behavior.     

Dielectric and piezoelectric properties of lead-free (Na0.5K0.5)NbO3-SrTiO3 ceramics

In this article, we report successful preparation of dense [(Na_0.5K_0.5)_1−xSr_x](Nb_1−xTi_x)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 (Na_0.5K_0.5)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 k_p=26.6-32.5% and k_t=39.8-43.8%. The results show that the [(Na_0.5K_0.5)_1−xSr_x](Nb_1−xTi_x)O₃ ceramics are one of the promising lead-free materials for electromechanical transducer applications.