PST陶瓷的微结构和电性能研究

研究了Pb含量对PbxSr1-xTiO3（x=0．2～0．8）陶瓷微结构和介电性能的影响，当x＜0.45时，c/a≈1，晶体为立方顺电相；x≥0．45时，c/a＞1，晶体为四方铁电相；随着Pb/Sr比增大，PST陶瓷气孔率下降，致密度增加，晶粒尺寸逐渐增大，居里峰近似线性地向高温方向移动，并具有一致的居里外斯常数，剩余极化强度（Pt）、矫顽场强（Ec）都增大。     

半化学法制备（Bi2-xNdx）（Zn1/3Nb2/3）2O7微波介电陶瓷与介电性能的研究

采用半化学法制备微波介电陶瓷（Bi2-xNdx）（Zn1/3Nb2/3）2O7（0≤x≤0.6），系统地研究了陶瓷的相结构及低频介电性能。结果表明：当Nd^3＋取代量较少伍≤0．25）时，样品的相结构仍然保持单斜焦绿石单相，随着Nd^3＋取代量的进一步增加，样品中出现立方焦绿石相，样品结构呈现单斜相与立方相的共存。同时，样品的介电性能随Nd^3＋取代量的变化为：介电常数先增大后减小，而介电损耗先减小后增大，在X=0.25处取得最佳电性能，分另1是εr=83，tanδ=0．0029（100kHz）。     

Na0.5Bi0.5TiO3-BaTiO3陶瓷的介电和压电性能研究

研究了Na0.5Bi0.5TiO3和（Na0.5Bi0.5）0．94Ba0．06TiO3陶瓷的电滞回线，压电性能和热滞现象。得到（Na0.5Bi0.5）0．94Ba0．06TiO3陶瓷的剩余极化Pr=19μC/cm^2，矫顽场Ec=4.7kV/mm.发现有适量的Ba^2 取代（Na0.5Bi0.5)^2 尽管压电性能有所提高，但同时使得材料的温度稳定性大大降低。     

V^5＋取代对Mg4（SbNb1-xVx）O9陶瓷介电性能的影响

研究了不同V5 含量Mg4(SbNb1-xVx)O9[MSNV,0.05≤x≤0.3]系陶瓷的烧结特性、微观结构和微波介电性能.结果表明:一定量V5 取代能够明显降低该陶瓷的烧结温度.在所有组成范围内,XRD显示了单一刚玉型结构.随V5 针含量的增加,样品的介电常数ε和品质因数Q·f先增大后减小,样品的谐振频率温度系数Tf逐渐减小,这是由于V5 的取代使得B位键价增强所致.在x=0.15,1250℃烧结,可获得εr=9.98,Q·f=20248GHz(8GHz),Tf=-23.3x10-6.K-1的新型微波介质陶瓷.     

Y3+取代Bi3+的Bi2O3-ZnO-Nb2O5基陶瓷的结构与介电性

研究了Y3 取代的Bi2O3-ZnO-Nb2O5(BZN)基陶瓷(Bi1.5-xYxZn0.5)(Zn0.5Nb1.5)O7(0≤x≤1.5,BYZN)的结构和介电性能.采用传统的固相反应法制备陶瓷样品,XRD分析样品的相结构,SEM分析样品的微观形貌.结果表明:BZN陶瓷的结构为立方焦绿石单相;当Y3 取代量较少(0＜x≤0.3)时,样品的相结构仍然保持立方焦绿石单相;随着Y3 取代量的进一步增加(x≥0.6),样品由立方焦绿石相向YNbO4和ZnO复相过渡.同时,样品的介电性能随结构的变化而呈现有规律的变化.     

Y2O3掺杂（Bi0．5Na0．5）0．94Ba0．06TiO3无压电陶瓷的研究铅

采用固相合成法制备了Y2O3掺杂（Bi0．5Na0．5）0．94Ba0．06TiO3无铅压电陶瓷。研究了Y2O3掺杂对（Bi0．5Na0．5）0．94Ba0．06TiO3陶瓷晶体结构、介电与压电性能的影响。XRD分析表明,在所研究的组成范围内陶瓷均能够形成纯钙钛矿固溶体。介电常数-温度曲线显示陶瓷具有弛豫铁电体特征,陶瓷的弛豫特征随掺杂的增加更为明显。在Y2O3掺杂量为0．5％时陶瓷的压电常数d33分别为137pC／N,为所研究组成中的最大值,掺杂量为0．1％时,机电耦合系数kp与kt最大值为0．30,0．47。     

Ta掺杂Na0.5 Bi4.5 Ti4O15陶瓷的显微结构和电性能EI北大核心CSCD

采用固相烧结法制备铋层结构Na 0.5 Bi 4.5 Ta x Ti 4-x O 15+0.5 x(NBT-Ta-x)(x=0~0.20)压电陶瓷。采用X射线衍射、扫描电镜和自动控温测试系统研究Ta 5+的B位掺杂对NBT-Ta-x陶瓷的微观结构、电导、介电和压电性能的影响。结果表明:随Ta掺杂量的增加,晶粒尺寸和长径比逐渐减小,表现出沿c轴的取向生长,同时,陶瓷的理论密度和体积密度增加,在掺杂量x=0.05时达到最高的相对密度96.1%,Ta在NBT晶格中的固溶极限在0.10附近。随Ta 5+掺杂量x增加到0.20,陶瓷的居里温度从680℃降至658℃。Ta 5+掺杂使NBT-Ta-x陶瓷的电阻率增加了两个数量级,压电常数d 33从13.8 pC/N增加到23 pC/N。当x=0.04~0.05时,NBT-Ta-x陶瓷的综合电性能良好:T c=670~672℃,d 33=21.8~23 pC/N,k p=7.9%~8.3%。     

Mg4（Ta1-xVx）2O9陶瓷的烧结特性和微波介电性能

用固相法制备了一系列Mg4(Ta1-xVx)2O9(MTV)陶瓷,研究了V5 取代Ta5 、MTV陶瓷的烧结特性和微波介电性能.用XRD和SEM研究其晶体结构和微观形貌.结果表明:在组分x≤0.3范围内形成了Mg4(Ta1-xVx)2O9连续固溶体.少量V5 取代Ta5 能够使MTV陶瓷的烧结温度从1450℃降至1150℃,但同时品质因数降低.x=0.1,1150℃烧结的Mg4(Ta1-0.1V0.1)2O9陶瓷具有较好的微波介电性能:ε约为11,Q·f值达41000GHz(8GHz).     

溶胶凝胶法制备钛酸锶钡(Ba1-xSrx)TiO3陶瓷及其介电性能的研究

采用硝酸钡、硝酸锶、钛酸丁酯和柠檬酸为原料的配合物溶胶凝胶方法制备了(Ba1-xSrx)TiO3(BST)陶瓷.实验结果表明,BST粉体合成温度及烧结温度分别为700及1250℃,均低于传统工艺的相应温度. Sr含量x≥0.40,(Ba1-xSrx)TiO3陶瓷的相结构为立方钙钛矿相;Sr含量x＜0.40,(Ba1-xSrx)TiO3陶瓷的相结构为四方钙钛矿型. (Ba1-xSrx)TiO3(0.5≤x≤0.70)陶瓷的电容率随温度变化曲线,说明存在由铁电四方相到顺电立方相的相变.且随锶(Sr)的摩尔量x的增加,(Ba1-xSrx)TiO3陶瓷样品的相变温度向低温方向移动,相变温度Tc的移动关系为Tc=394.1-272.6x(K).     

高能球磨制备钛酸锶铋陶瓷及其介电弛豫研究

采用高能球磨和固相烧结法制备了一系列Sr1-1.5xBixTiO3(SBT)陶瓷.采用XRD和SEM分析了样品的相结构和显微结构.结果表明,高能球磨过后的粉末为具有钙钛矿结构的SBT固溶体,且SBT陶瓷的固溶度有所提高.其介电性能结果表明,SBT的介电常数温度特性具有明显的弛豫现象,并且随Bi含量的增加,相转变温度向高温移动,相变弥散及弛豫程度增强,并对SBT陶瓷的弛豫机制进行了探讨.     

溶胶-凝胶技术制备(Bi4-x,Lax)Ti3O12陶瓷的工艺技术研究

采用3种溶胶－凝胶（sol-gel）工艺，以硝酸铋、硝酸镧和钛酸丁酯为原料，制备掺镧钛酸铋（Bi4-x,Lax)Ti3O12（简记为BLT）陶瓷。通过控制溶胶－凝胶工艺，分析比较不同溶胶－凝胶过程对陶瓷结构的影响，为后续BLT铁电薄膜的溶胶－凝胶制备选择最佳工艺技术条件。研究发现采用滴定方式的sol-gel工艺制备的陶瓷具有较好的取向和结构。     

SrTiO_3/CaCu_3Ti_4O_(12)复合陶瓷材料的介电性能

本文采用固相反应法制备了xSrTiO_3/(1-x)CaCu_3Ti_4O_(12)(x=0,0.2,0.4,0.6,0.8,1)复合陶瓷,研究了复合材料的物相、微观结构和宽温度宽频率范围内的介电性能。结果表明:在1348~1600K的温度范围内烧结能够得到致密性良好的xSrTiO_3/(1-x)CaCu_3Ti_4O_(12)(x=0,0.2,0.4,0.6,0.8,1)复合陶瓷。频率为100kHz时,样品的室温介电常数随SrTiO_3含量的增加而减少,从71358(x=0)单调减少至270(x=1),其变化规律遵循Lichtenecker法则。介电损耗随SrTiO_3含量的增加先增大后减少。当x=0.2时,样品与CaCu_3Ti_4O_(12)陶瓷的介电性能相似,存在低温的介电弛豫和巨介电常数平台。随着SrTiO_3含量的增加,复合陶瓷的低温介电弛豫激活能增大,介电响应被抑制,而高温介电响应由于高温电导的影响而增强,使得CaCu_3Ti_4O_(12)特有的巨介电常数平台随着SrTiO_3的增加逐渐消失,xSrTiO_3/(1-x)CaCu_3Ti_4O_(12)复合材料的温度依赖性增强。     

BaTiO3-ZnNb2O6陶瓷介电及储能性能研究

采用固相法制备(1-x)BaTiO₃-xZnNb₂O₆ (x=0.5mol%, 1mol%, 1.5mol%, 2mol%, 3mol%, 4mol%) (简称BTZN)陶瓷, 研究了BTZN陶瓷的烧结温度、结构、介电性能和铁电性能。BTZN陶瓷烧结温度随着ZnNb₂O₆含量增加逐渐降低。XRD结果表明当ZnNb₂O₆含量达到3mol%时出现第二相Ba₂Ti₅O₁₂。介电测试结果表明随ZnNb₂O₆含量的增加, BTZN陶瓷介电常数逐渐减小, 而介电常数的频率稳定性逐渐增强。介电温谱表明所有BTZN陶瓷均符合X8R电容器标准。BTZN陶瓷的极化强度值随着ZnNb₂O₆含量的增加逐渐降低。当x=4mol%时, BTZN陶瓷获得240 kV/cm的击穿电场和1.22 J/cm ³的可释放能量密度。     

Ferroelectric and piezoelectric properties of (1 − x) (Bi0.5Na0.5)TiO3–xBaTiO3 ceramics

Lead-free ceramics based on bismuth sodium titanate (Bi_0.5Na_0.5TiO₃, BNT)–barium titanate (BaTiO₃,BT) have been prepared by solid state reaction process. The (1?x)BNT–(x)BT (x = 0.01,0.03,0.05,0.07) ceramics were sintered at 1,150 °C for 4 h in air, show a pure perovskite structure. X-ray diffraction analysis indicates that a solid solution is formed in (1?x)BNT–(x)BT ceramics with presence of a morphotropic phase boundary (MPB) between rhombohedral and tetragonal at x = 0.07. Raman spectroscopy shows the splitting of (TO₃) mode at x = 0.07 confirming the presence of MPB region. The temperature dependence dielectric study shows a diffuse phase transition with gradual decrease in phase transition temperature (T_m). The dielectric constant and diffusivity increases with increase in BT content and is maximum at the MPB region. With the increase in BT content the maximum breakdown field increases, accordingly the coercive field (E_c) and remnant polarization (P_r) increases. The piezoelectric constant of (1 ? x)BNT–(x)BT ceramics increases with increase in BT content and maximum at x = 0.07, which is the MPB region. The BNT–BT system is expected to be a new and promising candidate for lead-free dielectric and piezoelectric material.     

High-power piezoelectric characteristics of textured bismuth layer structured ferroelectric ceramics

Abstract-The high-power piezoelectric characteristics in h001i oriented ceramics of bismuth layer structured ferroelectrics (BLSF), SrBi(2)Nb(2)O(9) (SBN), (Bi,La)(4)Ti(3)O(12) (BLT), and CaBi(4)Ti(4)O(15) (CBT), were studied by a constant voltage driving method. These textured ceramics were fabricated by a templated grain growth (TGG) method, and their Lotgering factors were 95%, 97%, and 99%, respectively. The vibration velocities of the longitudinal mode (33-mode) increased proportionally to an applied electric field up to 2.5 m/s in these textured BLSF ceramics, although, the vibration velocity of the 33-mode was saturated at more than 1.0 m/s in the Pb(Mn,Nb)O(3)-PZT ceramics. The resonant frequencies were constant up to the vibration velocity of 2.5 m/s in the SBN and CBT textured ceramics; however, the resonant frequency decreased with increasing over the vibration velocity of 1.5 m/s in the BLT textured ceramics. The dissipation power density of the BLT was almost the same as that of the Pb(Mn,Nb)O(3)-PZT ceramics. However, the dissipation power densities of the SBN and CBT were lower than those of the BLT and Pb(Mn,Nb)O(3)-PZT ceramics. The textured SBN and CBT ceramics are good candidates for high-power piezoelectric applications.     

Structural and dielectric properties of Bi doped Ba<Subscript>0.6</Subscript>Sr<Subscript>0.4</Subscript>TiO<Subscript>3</Subscript> ceramics

The dielectric properties of 0.1–15% mol bismuth doped Ba_0.6Sr_0.4TiO₃ (BST) ceramics have been investigated systematically. The solubility limit of bismuth is determined as about 10 mol% by means of both X-ray diffraction and scanning electron microscopy, which is further verified by the fact that the lattice constant of the samples above 10 mol% is almost invariable. The temperature dependence of the dielectric permittivity suggest that the ferroelectric behavior transit to relaxor ferroelectric type when impurity concentration reaches 5 mol%, and further to relaxor behavior for samples above 10 mol% Bi content, which is verified by the absence of a hysteresis loop. Thermal expansion results show differences between 5 and 10 mol% doped samples. Dielectric tunability at room temperature decreases with bismuth content increasing. The variation of properties was attributed to the impurity induced polar regions and former long-order structure.     

高Tc铋层状压电陶瓷结构与性能

综述了铋层状压电陶瓷的结构特点及性能研究．铋层状压电陶瓷的结构由（Ｂｉ_２Ｏ_２）^２＋层和钙钛矿层（Ａ_ｍ－１Ｂ_ｍＯ_３ｍ＋１）^２－按一定规则共生排列而成．此处 Ａ为适合干 １２配位的离子;Ｂ为适合于八面体配位的离子,ｍ为一整数,其值一般为１～５．与钛酸钡（ＢａＴｉＯ_３）或锆钛酸铅（ＰＺＴ）陶瓷相比,铋层状压电陶瓷具有以下特点：低介电常数、高Ｔ_ｃ、机电耦合系数各向异性明显、低老化率、高电阻率等． 先前研究证明,居里温度不仅与极化原子位移、自发极化强度、Ａ位Ｂｉ含量有关,而且还与取代离子的特性诸如离子半径、电负性、核外电子排布有关．压电活性低是铋层状陶瓷的本质缺点,通常发展该材料的途径为化学取代或晶粒取向技术．研究材料结构与性能之间的关系有助于发展铋层状压电陶瓷材料．     

铌镁酸铋-钛酸铅压电陶瓷准同型相界附近的性能和相变温度研究

利用传统固相烧结法制备了Bi(Mg_2/3Nb_1/3)O₃-PbTiO₃(BMN-PT)压电陶瓷, 分析了不同PbTiO₃含量对BMN-PT压电陶瓷的晶体结构、介电、压电及铁电性能的影响. XRD结果表明: 合成的BMN-PT陶瓷具有纯钙钛矿结构, 并且在PbTiO₃含量为x=0.60时, 其组分的XRD图谱在衍射角2θ=45°出现明显的分峰, 说明该组分相结构中存在三方和四方相的共存. 压电铁电性能显示, BMN-0.60PT有最大的压电常数d₃₃(~170pC/N)和平面机电耦合系数k_p(0.35), 最小的矫顽场E_c(29.4 kV/cm)及最大的剩余极化P_r(31.4 μC/cm²). 确定了BMN-PT压电陶瓷的准同型相界(MPB)为PbTiO₃含量x=0.60的组分. 介电系数温谱表明介电系数峰值温度(Tm)随着PbTiO₃含量的增大而升高, MPB组分的Tm约为276℃.     

含铋层状结构陶瓷CaBi2Nb2O9的A位掺杂改性研究

利用固相反应法合成了Ca1-x(KLa)x/2Bi2Nb2O9(x=0～0.20)(xKLaCBNO)铋层状陶瓷,分析不同KLa掺杂量对CaBi2Nb2O9(CBNO)基陶瓷微观结构、介电、压电及电导性能的影响.XRD分析表明KLa的引入未改变CBNO陶瓷的单相结构.SEM和介电系数温度谱结果分别显示,KLa掺杂量的增加,细化尺寸趋于一致,而居里温度(Tc)从943℃降低至875℃,其峰值介电常数减小、峰值介电损耗增大.当掺杂量x=0.1时,样品的高温电阻率较纯CBNO显著升高,压电系数d33由5.2 pC/N提高到15.8 pC/N,居里温度高达870℃,说明A位(KLa)掺杂改性后的CBNO陶瓷在高温传感器等领域具有潜在的应用前景.