掺钾对PMN基陶瓷有序微区及介电和电致伸缩性能的影响

使用二次合成法制备了不同钾含量的0.80Pb(Mg1/3Nb2/3)O3-0.20PbTiO3陶瓷，首先研究了掺钾对PMN基预烧粉体和陶瓷试样相组成的影响，在此基础上详细研究了掺钾对PMN基陶瓷有序微区、介电和电致伸缩性能的影响规律。掺钾对PMN基预烧粉体和陶瓷的相组成影响很小；理论计算和Raman散射光谱分析都表明掺钾使PMN基陶瓷的有序微区的尺寸稍微减小；掺钾也小幅度地减小了PMN基陶瓷的介电和电致伸缩性能，最后分析了掺钾降低介电和电致伸缩性能的原因。     

PZN基复相陶瓷介电性能和电致伸缩性能的研究

以不同居里温度的PZN基驰豫铁电陶瓷为原始高、低温组元,采用二次合成法制备出PZN基复相陶瓷,研究了PZN基复相陶瓷的介电性能和电致伸缩性能。结果表明：复相陶瓷温度稳定性好,弥散相变度大,在具有较大的电致应变的同时具有较小的滞后,表现出优异的介温特性和电致伸缩性能。     

掺钾PZN基陶瓷的有序微区及介电和电致应变性能研究

使用二次合成法制备了不同钾含量的O．85Pb(Zn1/3Nb2/3)O3-0．10BaTiO3-O．05PhTiO3陶瓷。首先研究了掺钾对PZN基预烧粉体和陶瓷相组成的影响。在此基础上详细研究了掺钾对PZN基陶瓷有序微区以及介电和电致应变性能的影响规律。掺钾对PZN基预烧粉体和陶瓷的相组成影响很小；理论计算和Raman散射光谱分析都表明掺钾使PZN基陶瓷的有序微区的尺寸稍微减小；掺钾也减小了PZN基陶瓷的介电和电致应变性能，并分析了掺钾降低介电和电致应变性能的原因。     

铅欠缺对PZN基陶瓷有序微区、介电和电致应变性能的影响

研究了初始粉体中氧化铅欠缺对PZN基陶瓷的相组成、有序微区、介电和电致应变性能的影响.研究发现,随着氧化铅欠缺量的增大,预烧粉体和陶瓷的焦绿石相含量逐渐增大、钙钛矿相含量逐渐减少.当铅欠缺小于1%时,随着铅欠缺量的增大, PZN基陶瓷的有序微区、介电常数和电致应变大幅度增大;而当铅欠缺大于1%时,铅欠缺会使介电和电致应变性能下降.而铅欠缺对介电损耗影响很小.铅欠缺使介电和电致应变性能增加的原因主要是由于"有效有序微区"尺寸的增大和晶界间过量氧化铅层的消除.     

PMN基复相弛豫铁电陶瓷电致应变及其温度稳定性的研究

用熔盐法制备的不同居里温度的Pb(Mg1/3Nb2/3)O3基陶瓷预烧粉体和烧结粉体为初始高、低温组元,采用混合烧结法制备出PMN基弛豫铁电复相陶瓷,研究了PMN基复相陶瓷的介电性能和电致伸缩性能及其温度稳定性.结果表明:采用烧结粉体制得的复相陶瓷不仅具有较大的介电常数(室温介电常数为8368)和电致应变2.8×10-4,而且在-10～ 70℃范围内温度稳定性也较好.     

Na0.5Bi0.5TiO3−BaTiO3−SrTiO3陶瓷的相图及电致伸缩性能

目的 利用SrTiO3调控Na0.5Bi0.5TiO3−BaTiO3−SrTiO3(NBT−BT−ST)三元系陶瓷的相结构,在室温下获得性能优异的电致伸缩材料,该材料可用于包装机械物料供给微振动器的研发。方法 采用传统固相合成法制备(1−x)[0.94NBT−0.06BT]−xST陶瓷。在分析(1−x)[0.94NBT−0.06BT]−xST陶瓷相图的基础上,阐述不同相区应变的来源,并系统研究弛豫相区陶瓷铁电、应变和电致伸缩性能等。结果 随着ST含量的增加,(1−x)[0.94NBT−0.06BT]−xST陶瓷的相结构由三方相、四方相两相共存→四方铁电相→铁电相、弛豫相共存→弛豫相。三方、四方两相共存区陶瓷的应变主要来源于晶格变形和非180^o畴转向。铁电、弛豫两相共存区陶瓷的应变主要来源于电场引发弛豫相和铁电相的相变。弛豫相区陶瓷的应变主要来源于样品晶格本征变形产生的电致伸缩效应。在弛豫相区,随着ST含量的增大,(1−x)[0.94NBT−0.06BT]−xST陶瓷的弛豫性增强,电滞回线逐渐变瘦,应变和滞后性均出现不同程度的降低,其中,x=0.40的样品在电场强度60 kV/cm下的应变滞后性降至7.8%,表现出典型的电致伸缩特征。在较强的弛豫性和形成纳米极性微区的作用下,在组分x=0.40时陶瓷在电场强度50 kV/cm下的电致伸缩系数高达0.021 3 m⁴/C²。结论 通过ST调控NBT基陶瓷的相结构,在弛豫相区能够有效地改善其电致伸缩性能。利用该技术制备的陶瓷电致伸缩材料可为包装机械物料供给微驱动器的研发和改进提供技术支持。     

Na0.5Bi0.5TiO3基无铅陶瓷的制备及电致伸缩效应研究

目的 在Na0.5Bi0.5TiO3基陶瓷材料中诱导缺陷来提高其电致伸缩性能,在室温下获得性能优异的电致伸缩材料,该材料可用于包装机械物料供给微振动器的研发。方法 利用传统固相合成法制备0.7(Bi0.5Na0.5)Ti0.9Mn0.1O3?0.3Sr(1?3x/2)Bix□x/2TiO3（NBT?SBxT?Mn）陶瓷。通过掺杂Sr(1?3x/2)Bix□x/2TiO3,在陶瓷中形成VA?VO局部缺陷,获得具有极性纳米微区的非极性相结构。同时,通过掺杂MnO在陶瓷中形成Mn?VO缺陷偶极子,获得滞后小的电致伸缩应变。结果 所制备的样品均表现出极性纳米微区的非极性相结构和弥散度高于1.80的典型弛豫特征。随着x的增加,氧空位的含量先降低后明显增大。氧空位含量的降低表明在NBT?SBxT?Mn陶瓷中形成了Mn?VO缺陷偶极子。在VA?VO局部缺陷、Mn?VO缺陷偶极子、较高弛豫性及形成的极性纳米微区的共同作用下,组分x=0.07样品的电致伸缩系数高达0.036 m4/C2,性能优异。结论 通过在NBT基陶瓷材料中诱导缺陷能够有效改善其电致伸缩性能。     

夹心复合压电陶瓷的介电响应

夹心复合压电陶瓷由多孔陶瓷及其上下两层致密陶瓷组成。本工作研究了这种夹心复合压电陶瓷在100Hz～1000MHz 范围内的室温介电响应。这种材料在数百兆赫时出现介电弛豫,频响特性符合 Jonscher 提出的普适介电定律,介电指数 n 和 m 与多孔陶瓷的气孔率有关。经人工极化的样品,介电频响曲线上出现另外两处反常变化,分别相应于径向振动和厚度伸缩振动的贡献。     

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。     

铌酸镁的合成与铌镁酸铅基电致伸缩陶瓷性能关系研究

研究了不同温度MgNb2O6的原始合成反应,结果显示游离MgO的含量随MgNb2O6合成温度的升高而减少．首先合成MgNb2O6,但合成时并不加入过量MgO,合成温度为1050℃,由此制备了一种PMN基电致伸缩陶瓷．在X射线衍射检测极限内,并未发现此PMN基电致伸缩陶瓷存在焦绿石第二相．对该陶瓷施加1kV／mm频率为0．07Hz的准静态电场,在室温下其纵向电致应变（S11）达1．05×10－3而滞后仅为6．8％．还研究了MgNb2O6的合成温度与PMN基陶瓷电致伸缩性能的关系,它表明PMN基陶瓷的居里温度Tc随MgNb2O6的合成温度的提高而增高,从而引起介电常数的下降和滞后增大．     

PMN基电致伸缩陶瓷电致应变温度特性

研究了扩散相变中心温度分别为４０℃和６５℃的两种Ｌａ－掺杂ＰＭＮ基陶瓷在其扩散相变温度范围的电致应变、电致应变随电场（Ｓ～Ｅ）的滞后特性和剩余应变效应．结果发现,对于扩散相变中心温度为４０℃的材料在０～１ｋＶ／ｍｍ单向电场驱动下;从－１０～６０℃电致应变和滞后都随温度的升高而减小;对另一种材料无论由±１ｋＶ／ｍｍ交变电场或由０～１ｋＶ／ｍｍ单向电场驱动,温度从１３～４１℃变化均出现电致应变峰值,而滞后和剩余应变随温度的升高而减小．对以上实验结果本文作了详细讨论．     

A位Sm掺杂对0.93Na0.5Bi0.5TiO3-0.07BaTiO3陶瓷微结构及电学性能的影响

采用固相反应烧结方法制备了Sm掺杂的[(Na_0.5Bi_0.5)_0.93Ba_0.07]_1-xSm_xTiO₃(BNBST)无铅介电储能陶瓷, 系统研究了Sm掺杂含量对BNBST陶瓷的相结构、微观结构、铁电、介电、储能和交、直流电导的影响。研究结果表明: 制备的陶瓷样品具有单一的钙钛矿结构, Sm掺杂固溶于(Na_0.5Bi_0.5)_0.93Ba_0.07TiO₃基材的晶格A位; 晶粒生长被Sm掺杂抑制, 平均晶粒尺寸在2 μm内, 且均匀致密; Sm掺杂显著降低了剩余极化和矫顽场, 表现出双电滞回线特性, 但饱和极化也略有降低; 储能密度和效率随Sm掺杂量增加先增大后减小, 在x=0.02和电场为70 kV/cm时获得最大储能密度0.70 J/cm³, 其效率为40%; BNBST陶瓷具有明显的弛豫铁电体特征, 其介电常数峰T_m随掺杂量增加而降低且平坦化; BNBST陶瓷的绝缘性有较强的温度依赖性, 300℃以下具有良好的绝缘性。     

Polarization-electric field relations of ferroelectric/antiferroelectric layered ceramics in Pb(Nb, Zr, Sn, Ti)O3 system

Ferroelectric/antiferroelectric bi-layer ceramics with different ferroelectric and antiferroelectric phase thickness ratio (FE/AFE thickness ratio) in Pb(Nb, Zr, Sn, Ti)O₃ system were prepared and characterized. With increasing the maximum external electric field from 0 to 40 kV/cm, polarization-electric field relation was always ferroelectric-like or underwent an antiferroelectric-ferroelectric transition, depending on the FE/AFE thickness ratio. All layered ceramics showed ferroelectric-like hysteresis loops with maximum external electric field of 40 kV/cm, and much higher remanent polarizations were attained than those of the ferroelectric/antiferroelectric heterostructures reported previously.     

Effects of lanthanum modification on electrical and dielectric properties of Pb(Zr0.70,Ti0.30)O3 ceramics

Lanthanum modified lead zirconate titanate ceramics with lanthanum content changing from 7.6 to 9.0 at.% La and a Zr/Ti ratio of 70/30 (PLZT 100x/70/30) have been prepared by conventional high temperature solid-state reaction technique. The studies of the ferroelectric, electromechanical and dielectric properties of the ceramics were carried out. The results showed the enhanced antiferroelectricity stability when the lanthanum content increases. The polarization and strain decreased with the increasing La content. The dielectric spectra of all the PLZT samples show a dispersive behavior. With increasing La concentration, the maximum dielectric constants ε_m and the transition temperatures T_m were reduced.     

Effects of La concentration on the structural and dielectric properties of 0.57BiFeO3-0.43PbTiO3 crystalline solutions

Crystalline solutions of 0.57(Bi(1-x)La(x))FeO(3)-0.43PbTiO(3) (BLF-PT) for x = 0, 0.1, 0.2, and 0.3 were fabricated by the traditional solid state reaction method. X-ray diffraction analysis revealed that the tetragonal torhombohedral phase transformation of BLF-PT occurred with an increase of the La content. The dielectric and ferroelectric properties of BLF-PT were investigated at room temperature for different La contents. BLF-PT revealed strong ferroelectric characteristics for the lower La composition, and transferred to relaxor ferroelectrics for x 0.2. The dielectric constant and remanent polarization were 1461 and 33.5 microC/cm(2), respectively, for BLF-PT of x = 0.2. The dielectric constant and polarization of BLF-PT were enhanced simultaneously with increasing La content. Our results demonstrate that BLF-PT is a competitive piezoelectric ceramic.     

The use of harmonic analysis of the strain response inPb(Mg1/3Nb2/3)O3-based ceramics tocalculate electrostrictive coefficients

The electromechanical response of ceramics has long been described with Landau Devonshire phenomenology, wherein the strain response is linked to a polynomial expansion in electric field or dielectric displacement. Consequently, the electromechanical response has been modeled with a variety of basis functions. However, these models have failed to accommodate hysteresis and the harmonic response that arises with saturation phenomena. In addition, no quantitative criterion has been used to truncate the expansion. By implementing a discrete Fourier transform in conjunction with Devonshire phenomenology, these three problems can be overcome as demonstrated with a dielectrically aged, lead magnesium niobate relaxor ferroelectric well above its T_max , i.e., operating in the electrostrictive regime