PMN-PT透明光电陶瓷材料的特性及制备技术

以传统的光电材料铌酸锂晶体和透明光电陶瓷材料PLZT(镧改性的锆钛酸铅固熔体)作为比较,介绍了铌镁酸铅(PMN)-钛酸铅(PT)(简称PMN-PT)光电透明陶瓷的结构和性能优势,主要介绍了PMN-PT各种粉末的制备方法、烧结工艺方法及其各自的特点,同时对影响陶瓷透明的因素和基于该材料的器件和应用进行了简要介绍.     

PMN-PT/P(VDF-TrFE)复合材料的制备与电性能研究

以铌铁矿预产物法合成的铌镁酸铅-钛酸铅(PMN-PT)陶瓷粉体和聚二氟乙烯-三氟乙烯共聚物P(VDF-TrFE)为原料,采用流延法在ITO衬底上制备了不同质量配比的PMN-PT/P(VDF-TrFE)复合厚膜。采用XRD及SEM分别分析了PMN-PT粉体的物相结构和复合材料的界面特征。通过测试复合材料的介电-温度曲线,计算出加载在陶瓷相上的极化分压与温度的关系,得到优化的极化温度。与常规的分步极化相比,探讨了在优化极化条件下陶瓷相含量对复合材料热释电性能的影响,结果表明在极化温度为110℃,PMN-PT质量分数为55%时,得到了热释电系数为58.6μC/(m2·K)的热释电复合厚膜材料。     

常压烧结制备透明铌酸钾钠陶瓷

在铌酸钾钠(KNN)陶瓷中掺杂锂和铋的氧化物作为晶粒生长抑制剂,用常压烧结工艺制备了铌酸钾钠透明陶瓷(K0.48-0.5xNa0.52-0.5xLixNb1-xBixO3,x=0.04～0.15)材料。研究了掺杂量、烧结工艺条件对陶瓷透明性、光电系数、晶相结构和微观形貌的影响。当x=0.09时,厚度为0.5mm陶瓷样品的红外透光率达到82%,光电系数为6.06×1011m/V。     

锰掺杂对PMN-PZT陶瓷介电性能的影响

研究了锰掺杂对富锆PMN-PZT（铌镁酸铅一锆钛酸铅）陶瓷材料的相组成、微观结构、介电性能等方面的影响，并对实验结果作出物理机理的解释。实验结果表明：适量的锰掺杂有助于陶瓷晶粒的生长，并能有效地降低PMN-PZT陶瓷材料的介电常数和介电损耗，在锰掺杂量为3．0％（原子分数）时，εr：197、tanδ=0．15％，作为用于红外热释电探测器的陶瓷材料具有良好的介电性能。     

PNC—3型偏铌酸铅压电陶瓷高温性能的研究

(一) 偏铌酸铅压电陶瓷有着一些突出的特点,如低的Qm值(Qm<10)、单一的振动模式(Kt>>Kr)和较高的居里温度(Tc=570 C),在工业检测、医疗诊断与高温传感器方面有着十分广阔的应用前景。但是纯的偏铌酸铅,因高温铁电相在常温下是很不稳定的,因而要制备出具有压电性良好的偏铌酸铅压电陶瓷是比较困难的。为了制得可应用的偏铌酸铅压电陶瓷,大多采用Ba置换与添杂的方法来现实。Ba的置换能大大地提高材料的压电性能,但压电性能的稳定性随着Ba置换量的增加而急剧变坏。虽然以往曾有过一些改性偏铌酸铅陶瓷料材在使用,但工艺性差,不能制作稍大一…     

铌酸钾钠压电陶瓷制备工艺研究进展

压电陶瓷是一种具有力电转换效应的功能陶瓷，已被广泛应用于医疗、传感器、超声马达等领域。由于无铅压电陶瓷在制备过程中避免了铅挥发，属于环境友好型材料，成为目前国内外研究的重点。铌酸钾钠陶瓷是无铅压电陶瓷中电学性能较好的陶瓷之一，其电学性能在很大程度上受制备技术及其工艺的影响。固相烧结技术是目前铌酸钾钠陶瓷制备最成熟的技术。铌酸钾钠陶瓷制备过程主要包括粉体合成、压制成型和烧结成瓷三步。通过粉体合成工艺可制备出高织构化铌酸钾钠陶瓷的粉体模板，但存在不同程度的软团聚和硬团聚现象；压制成型可以制备出简单的陶瓷坯件，但受模具和辅助工具影响较大，精度低、结构简单、需二次加工、不适合批量生产。针对烧结过程中由高温导致的元素挥发不能被很好地抑制的问题，深入研究低温烧结、抑制钠钾元素挥发对铌酸钾钠陶瓷的优异制备有着深远意义。本文综述了近年来铌酸钾钠陶瓷固相烧结制备工艺的研究进展，对粉体合成、压制成型、烧结成瓷三步进行了系统的论述。通过分析粉体合成、压制成型和烧结制备工艺的优点与不足，重点讨论其对铌酸钾钠陶瓷微观组织和电学性能的影响机制，以期为制备高电学性能铌酸钾钠陶瓷提供参考，并为其在医学与工业领域的应用...     

高d_(31)、高 E_c 值压电陶瓷材料的研究

本工作研究了锆—钛—铌锌酸铅和锆—钛—铌锌—铌镍酸铅系压电陶瓷,同时研究了钡、锶和铋等元素置换铅以及工艺条件对压电性能的影响,获得了|d_(31)×E_c|值高达3.56×10~(-4)的压电陶瓷新材料.     

铌锌酸铅基陶瓷的电致伸缩特性与极化机制

系统地测度了铌锌酸铅基系列陶瓷ＰＺＮ－ＢＴ－ＰＴ（８５－１０－５，８０－１０，７５－１０－１５）的电致伸缩应变，电滞回线和介电性能，研究了它们的电诱应变同极化强度关系。     

钛酸铅陶瓷的快速制备及电性能研究

针对传统的Slo-gel法制备钛酸铅铁电陶瓷水解速率慢、烧结温度高、制备周期长等不足，首次采用在溶胶中直接加甲醇水溶液水解和新鲜凝胶直接烧结的方法，实现了钛酸铅纳米晶的快速合成。用TEM观察了钛酸铅纳米晶的形貌和尺寸，用XRD法测定了钛酸铅纳米晶的结构，并制得纯度高、致密性好的钛酸铅纳米陶瓷，对其介电、铁电和热释电性能进行了初步研究。研究表明，用改进的Sol-gel法制备的钛酸铅陶瓷仍保持其优良的介电性能和铁电性能。     

掺杂对PMN-10PT铁电陶瓷介电性能的影响

铌镁酸铅与钛酸铅组成比为9:1(PMN-10PT)的固溶体陶瓷是典型的弛豫铁电体,其介电行为与偶极玻璃的介电行为极为相似.本文使用常用的Swartz两步法,研究了基体掺杂不同物质对PMN-10PT铁电陶瓷的介电性能的影响.经研究发现,当掺入Li₂O时,材料的峰值介电常数为28640,大于纯PMN-10PT,而频率色散和弥散相变的程度都变小.当掺杂CaO和Yb₂O₃时,材料的峰值介电常数下降,分别为19300和18850,它们的频率色散和弥散相变的程度都变大了.同时通过拉曼光谱研究了PMN-10PT陶瓷的B位离子有序度的变化.     

相组成对PMN-PT陶瓷压电性能的影响

研究了ＰＭＮ－ＰＴ陶瓷在准同型相界（ＭＰＢ）区域、不同烧结温度下,化学组成、相组成对陶瓷压电性能的影响．发现对于同一化学组成的陶瓷,随着烧结温度的上升,发生了菱方相→四方相的相转变,同时随着菱方相、四方相相比例的接近,陶瓷的压电性能有显著的提高．而在不同烧结温度下,最佳压电性能所对应的化学组成有微小的变化．据此认为,陶瓷的压电性能不仅与化学组成有关,而且与相组成也密切相关,随着烧结温度的变化,发生了准同型相界的微小移动     

Intrinsic polarization and resistive leakage analyses in high performance piezo-/pyroelectric Ho-doped 0.64PMN-0.36PT binary ceramic

This paper presents in detail the ferroelectric properties of Ho-doped 0.64Pb(Mg_1/3Nb_2/3)O₃-0.36PbTiO₃ ceramic including determination of intrinsic polarization and investigation of resistive leakage. The effect of Ho³⁺ doping on the structure, dielectric, piezoelectric and ferroelectric properties of PMN-PT ceramics was studied. Perovskite phase of pure and Ho-doped 0.64Pb(Mg_1/3Nb_2/3)O₃-0.36PbTiO₃ ceramics were synthesized using solid state reaction method. Powder XRD confirmed the incorporation of Ho³⁺ ions in PMN-PT lattice. EDX spectra confirmed the existence of Ho and its homogeneity in doped-sample. The average grain size, transition temperature and dielectric loss factor (tan δ) decreased while the density and the dielectric constant of the PMN-PT ceramic increased by Ho doping. Furthermore, an increase in the ferroelectric properties and the piezoelectric coefficient (d₃₃¹, from 547 to 610?pm/V) were observed for doped sample. The ‘Remanent Hysteresis Task’ revealed that a major portion (80.42%) of the remanent polarization (P_r) is switchable in the sample which makes Ho-doped PMN-PT a potential material for memory switching devices. Time-dependent compensated (TDC) hysteresis task and fatigue test were carried out which revealed resistive leakage and fatigue free nature of Ho-doped PMN-PT ceramic. These results demonstrate that Ho-doped PMN-PT ceramic possesses excellent properties to achieve a variety of applications.     

Lead magnesium niobate-lead titanate fibres by a modified sol-gel method

Lead magnesium niobate-lead titanate (PMN-PT) ceramic fibres with the nominal composition of 0.65Pb(Mg_1/3Nb_2/3)O₃-0.35PbTiO₃ have been fabricated by a modified sol-gel method. Due to the difficulty of dissolving the magnesium component, the mixed oxide method was used together with the traditional sol-gel method. To obtain crack-free fibres, pyrolysis was carried out at a very slow heating rate under specific atmosphere to control the organic burnout. The thermal and microstructural properties were investigated using thermogravimetric analysis, scanning electron microscopy and X-ray diffraction. The optimum sintering temperature is 1200 °C and yields a fibre with a final diameter of around 100 μm. A single PMN-PT fibre has been poled and its electrical properties were measured. The properties of the fibre are found to be better than that of a ceramic disc.     

Single crystal PMN-PT/epoxy 1-3 composite for energy-harvesting application

One key parameter in using electroactive materials to harvest electric energy from mechanical sources is the energy conversion efficiency. Recently, it was shown that, in the relaxor ferroelectric PMN-PT single crystals, a very high longitudinal electromechanical coupling factor (>90%) can be obtained. This paper investigates energy harvesting using 1-3 composites of PMN-PT single crystals in a soft epoxy matrix. It is shown that 1-3 composites enable the single crystals operating in the longitudinal mode to achieve high efficiency for energy harvesting, and the soft-polymer, matrix-supported single-crystal rods maintain high mechanical integrity under different external loads. For comparison, 1-3 composites with piezoceramic PZT also are investigated in energy-harvesting applications, and the results show that the high coupling factor of single crystal PMN-PT 1-3 composites leads to much higher electric energy output for similar mechanical energy input. The harvested energy density of 1-3 composite with single crystal (22.1 mW/cm3 under a stress of 40.4 MPa) is about twice of that harvested with PZT ceramic 1-3 composite (12 mW/cm3 under a stress of 39 MPa). At a higher stress level, the harvested-energy density of 1-3 PMN-PT single crystal composite can reach 96 mW/cm3.     

复合X7R多层陶瓷电容器

介电常数Ｋ高于 ７２００的、具有满足 Ｘ７Ｒ（－５５～１２５℃,±１５％）规范要求的低烧复合多层陶瓷电容器（ＣＭＬＣＣｓ）已经研制成功．该电容器是由四种具有不同介温特性的ＰＭＮ－ＰＮＮ－ＰＴ和ＰＭＮ－ＰＴ体系的瓷介质膜片按一定布局复合构成．其内部显微结构良好．本研究表明,采用不同材料共烧以得到具有优良性能的片式元件是可行的．     

Modeling of elastic nonlinearities in ferroelectric materials including nonlinear losses: application to nonlinear resonance mode of relaxors single crystals

(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) and (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-PT) single crystals are considered to behave like soft Pb(Zr,Ti)O3 (PZT) ceramics because of their small mechanical quality factor Qm and poor stability under external disturbances (Qm > 500-1000 for hard PZT ceramic, and Qm < 100 for soft PZT and PMN-PT and PZN-PT single crystals). At weak signal excitation of the first resonance mode, the displacement at the end of a lateral bar is proportional to the Q31d31 figure of merit that is very close to that found for hard PZT. Indeed the very large piezoelectric coefficient compensates the low Qm. But increasing alternating current (AC) field results in the appearance of strong non-linearities through a shift of the resonance frequency and jumps phenomenon observed on increasing and decreasing frequency sweep. It is shown in this paper that these nonlinearities are due to the nonlinear elastic compliance that can be modeled by a third order development of the constitutive piezoelectric equations. Experiments on PMN-PT and PZN-PT single crystals are used for comparison with the model to show the viability of the approach. Both the frequency shift and jumps phenomenon are simulated with a very good agreement with experimental results. The importance is also shown of losses associated with the third order term responsible for the large decrease of the mechanical quality factor for high strain levels. Thus, the nonlinear losses are related to the hysteresis of domain wall motion when subjected to large displacements.     

PMN—PT粉体的溶液化学法制备

采用溶液化学法合成了驰豫型复合钙钛矿结构铁电PMN—PT粉体。对合成过程中的组分、预烧工艺进行了研究。用XRD对合成材料物相进行了分析,研究了煅烧温度对焦绿石相产生的影响,用SEM观察了晶粒形貌特征。结果表明预烧温度为500℃,经1150℃煅烧获得的粉体钙钛矿相达到99．4％,颗粒分散性良好。     

Magnetoelectric effect in square FeCo/PMN-PT/FeCo trilayer prepared by electroless deposition

A multiferroic square FeCo/PMN-PT/FeCo trilayer has been constructed by electroless depositing. Scanning electron microscopy reveals that the magnetostrictive FeCo layers are in direct contact with the piezoelectric single crystal PMN-PT substrates. It is shown that electroless deposition is an effective way to deposit films on single crystal PMN-PT. Thanks to the excellent piezoelectric performance, the composite adapting PMN-PT as piezoelectric phase possess a higher magnetoelectric coefficient than that of traditional PZT piezoelectric ceramics with the same configuration. For the square FeCo/PMN-PT/FeCo sample, six obvious resonance peaks can be observed in the dependence of the magnetoelectric coefficient on the magnetic field frequency due to the complex vibration mode, which makes this structure suitable for applications in multifunctional devices with multifrequency operation.     

Effects of ferroelectric/metal interface on the electric properties of PMN-PT thin films epitaxially grown on Si substrates

Lead magnesium niobate-lead titanate 0.72Pb(Mg_1/3Nb_2/3)O₃-0.28PbTiO₃ (PMN-PT) ferroelectric thin films were deposited on SrRuO₃ (SRO), SrTiO₃, and TiN-buffered Si substrates by pulsed laser deposition. X-ray diffraction θ–2θ and Phi scans reveal that PMN-PT films were epitaxially grown on Si substrates. Pt, Al, and Gd metals were employed as top electrodes to investigate the ferroelectric and dielectric properties of these metal/PMN-PT/SRO capacitors. It was found that the coercive field (E _C) of the Gd(or Al)/PMN-PT/SRO capacitor is 4.5 times larger than that of the Pt/PMN-PT/SRO capacitor while the permittivity for the former is only ~27 % of that for the latter, which is analyzed using the model for metal-ferroelectric-metal heterostructures with Schottky contacts. Compared with the Pt/PMN-PT/SRO capacitor, the higher E _C and lower permittivity of the Gd(or Al)/PMN-PT/SRO capacitor are attributed to the stronger space charge field at the Gd(or Al)/PMN-PT interface. The capacitance–voltage characteristics of the metal/PMN-PT/SRO capacitors were also discussed.     

Structural characterization of 0.5PbMg1/3Nb2/3O3-0.5BaxPb(1−x)TiO3 powders

The present work reports the effects caused by barium on phase formation, morphology and sintering of lead magnesium niobate-lead titanate (PMN-50PT). Ab initio study of 0.5Pb(Mg_1/3Nb_2/3)O₃-0.5(Ba_xPb_(1−x)TiO₃) ceramic powders, with x = 0, 0.20, and 0.40 was proposed, considering that the partial substitution of lead by barium can reestablish the equilibrium of monoclinic-tetragonal phases in the system. It was verified that even for 40 mol% of barium, it was possible to obtain pyrochlore-free PMN-PT powders. The increase of the lattice parameters of PMN-PT doped-powders confirmed dopant incorporation into the perovskite phase. The presence of barium improved the reactivity of the powders, with an average particle size of 120 nm for 40 mol% of barium against 167 nm for the pure sample. Although high barium content (40 mol%) was deleterious for a dense ceramic, contents up to 20 mol% allowed 95% density when sintered at 1100 °C for 4 h.