BSMPTx高温压电陶瓷的结构和介温特性

采用传统固相方法制备了(1-x)(0.15BiScO3-0.85PbTiO3)-xBi(Mg1/2Ti1/2)O3(BSMPTx)压电陶瓷体系,并利用XRD,SEM,介温等仪器和方法分析表征样品。XRD测试结果显示,Bi(Mg1/2Ti1/2)O3有助于0.15BiScO3-0.85PbTiO3陶瓷的烧结,当x=0.05～0.1时,可获得单一四方相钙钛矿结构的BSMPTx陶瓷,BSMPTx体系具有较大的四方畸变度(c/a>1.1);介温测试表明BSMPTx体系的居里温度高于没有掺杂0.15BiScO3-0.85PbTiO3陶瓷,其居里温度Tc超过500℃,最高的居里温度组分为BSMPT0.1,Tc～540℃;实验表明该压电陶瓷体系的弱压电活性跟较大的四方畸变有关系。     

高温压电陶瓷研究进展

评述了碱金属铌酸盐、钨青铜结构、铋层状结构和钙钛矿结构等高温压电陶瓷体系的结构和性能,重点介绍了复合钙钛矿固溶体系Bi(Me)O3-PbTiO3的研究进展.总结了影响压电陶瓷Curie温度的影响因素.提出了高温压电陶瓷今后的研究方向:一方面根据容差因子和Curie温度的关系开发新的高温压电体系:另一方面通过掺杂改性和工艺优化增加钙钛矿结构的稳定性并提高其性能.     

PbNb2O6基压电陶瓷的高温介电性能研究

本文在PbNb2O6基础上采用Ba^2＋取代Pb^2＋离子,并通过添加Cr2O3、Y2O3、Sm2O3、Nd2O3和CeO2等氧化物进行掺杂改性,研究不同掺杂剂对PbNb2O6陶瓷材料结构的影响,寻找提高压电性能及居里温度的途径.试验结果表明,掺杂后的偏铌酸铅显微结构发生了变化,适量的掺杂可获得压电性能和工艺稳定性能很好,且居里温度较高（420℃～600℃）的改性PbNb2O6系压电陶瓷,可分别满足350℃和500℃以上高温应用环境的要求.     

复合钙钛矿陶瓷的结构与微波介电性能

介绍了复合钙钛矿化合物结构的本质特征，讨论了钙钛矿结构对微波介质陶瓷材料的介电性能（介电常数、介质损耗、频率温度系数）的各种影响因素。     

锰掺杂对压电陶瓷介电性能的影响

采用传统的电子陶瓷工艺制备了高性能四元系压电陶瓷（PZN-PMS-PZT）。考察了不同剂量锰掺杂对压电陶瓷的室温介电常数（εTr)，介电常数温度谱以及居里温度（Tc)的影响。实验结果表明：随着Mn含量的增加，压电陶瓷的室温介电常数εTr减小；由于内偏置场的影响，居里温度Tc随锰含量的增加而增加。     

钙钛矿结构无铅压电陶瓷的研究进展

无铅压电陶瓷的开发与应用是当今压电陶瓷发展的必然趋势,本文综合分析了无铅压电陶瓷的研究背景,给出了钙钛矿型无铅压电陶瓷的主要体系,包括钛酸钡基无铅压电陶瓷、BNT基无铅压电陶瓷,分析比较了其性能及研究现状。     

La置换Pb对Sb掺杂PZT压电陶瓷介电和压电性能的影响

研究了Pb1–xLax(Zr1–yTiy)1–x/4O3+1.5%(质量分数)Sb2O5陶瓷(PLSZT)的介电、压电性能及其微观结构,获得了高压电性能、小晶粒尺寸的压电陶瓷材料。结果显示:x≤5%时,晶体结构为纯钙钛矿相;x>5%时,为钙钛矿和焦绿石两相混和物。随着x的增大,介电常数和压电常数均呈现先增大后减小的趋势。介电常数在x=6%、y=0.45时最大,最大介电常数εmax≈3900,介电损耗tgδ≈1.8%;压电性能在x=4%、y=0.45时最强,压电应变常数d33≈600pC/N,径向机电耦合系数kp≈0.7,厚度机电耦合系数kt≈0.51,此时的平均晶粒尺寸约为2μm。     

CaLa4Ti4O15微波介电陶瓷的制备和性能

采用固相法制备了Cata4Ti4O15系微波介质陶瓷.研究了不同预烧温度对CaLa4Ti4O15陶瓷烧结特性和微波介电性能的影响.在1 200℃预烧caLa4Ti4O15粉末.除CaLa4Ti4O15主相外,还存在部分CaTiO3,La2Ti2O7和La2TiO5混合相.在1 300℃和1 400℃预烧后.获得了六方类钙钛矿CaLa4Ti4O15单相.CaLa4Ti4O15粉末预烧后可饶结成高致密陶瓷(相对密度约97%),同时具有高机械品质因数与谐振频率的乘积(Q×f)值和近零谐振频率温度系数(Tf).1 550℃烧结的CaLa4Ti4O15陶瓷具有优异的微波介电性能:相对介电常数εr=45.1,Q×f=46087GHz,tf=-14.1 × 10-6/℃(预烧温度1 200℃);εr=-45.9,Q×f=48871GHz,tf=-14.4 ×10-6/℃(预烧温度1 300℃).     

PMZN压电陶瓷的工艺研究

为了优化Pb(Mn1 3Sb2 3) x(Zn1 3Nb2 3) y(Zr ,Ti) zO3系压电陶瓷的介电性能 ,探讨了不同烧结温度及保温时间对材料性能的影响 ,以期获得材料的最佳制备工艺。实验结果表明 ,此四元系材料具有较宽的烧结温度范围 ,随保温时间的延长材料的性能提高 ,最终达到一个饱和值 ;在 12 0 0～ 12 2 0℃烧结工艺条件下 ,材料的机电耦合系数与机械品质因数最大 ,介电损耗最小 ,介电常数适中 ,可望用于高性能超声换能器的研制     

Pb 1-xSrx(Mn1/3Sb2/3)aZrbTicO3三元系压电陶瓷的压电和介电性能

对Pb 1-xSrx(Mn1/3Sb2/3)aZrbTicO3+0.2%(质量分数)CeO2 (PMS-PZ-PT)三元系压电陶瓷的烧结温度(1 150～1 225 ℃)和Sr2+取代量(摩尔分数0～8%)进行了系统研究. 通过XRD图谱计算的晶格参数说明Sr2+取代Pb2+后, 晶胞更趋于各向同性且产生收缩, 从而改善样品的性能. 实验结果表明 当x=0.02时, 在1 200 ℃, 2 h条件下烧结, 能获得优良的综合性能εr =1 461, tanδ=0.003 8, Kp=0.63, Qm=1 321, d33=409×10-12 C·N-1, 可以满足超声马达和压电变压器等应用方面的要求.     

高Qm,低损耗压电陶瓷材料的研究

本文对ＰｂＯ３四元素和以ＣｅＯ２掺杂的ＰｂａＳｒ１－ａＯ３三元系压电陶瓷进行了研究。该材料具有高机械品质因数、低介电损耗、高居里点、高机械强度、烧结范围宽、工艺重复性好等特点。这两种材料在驻波超马达中得到了应用。     

固有烧结温度低的微波介质陶瓷

微波介质陶瓷是现代通讯技术中的关键基础材料。在制备多层微波介质片时,为了使用Cu、Ni等低熔点电极,必须降低微波介质陶瓷的烧结温度。开发固有烧结温度低(<1060℃)同时具有良好性能的微波介质材料成为必然的选择。本文简要介绍了7类固有烧结温度低的微波介质陶瓷的烧结特性与微波介电性能,同时也指出了研究中存在的一些问题。     

高介电常数微波介质陶瓷

近年来，微波介质陶瓷作为现代通信技术中关键的核心材料，广泛应用于微波谐振器、滤波器、介质基板、移相器等微波元器件，极大的促进了现化通信事业的飞速发展。本文综述了高介电常数微波介质陶瓷近几十年来的研究进展，并对高介电常数微波介质陶瓷的发展趋势进行了讨论和展望。     

Phase Transition and Failure at High Temperature of Bismuth-Layered Piezoelectric Ceramics

High-temperature bismuth-layered piezoelectric ceramics (Ca _x Sr_{1− x} )Bi₄Ti₄O₁₅ have been prepared by the conventional solid reaction method. Our results reveal that there is a "phase transition induced by the composition" taking place in the solid solution at around x =0.4. During transition, the crystal structure changes from orthorhombic to pseudo-tetragonal and then back to orthorhombic. Although all (Ca _x Sr_{1− x} )Bi₄Ti₄O₁₅ (with any x value) undergo a second-order ferroelectric-to-ferroelectric phase transition at about 200°C below their Curie temperature, only the ceramic with x =0.4 exhibits a failure in piezoelectric properties during the transition. It is suggested that, on the basis of the X-ray photoelectron spectroscopy results, this material failure is induced by the high concentration of oxygen vacancies in the material during the phase transition.     

低介电高强度多孔氮化硅陶瓷的研制

以氮化硅为基体,通过加入一定量的特殊无机添加剂,控制好相关工艺参数成功地制备出低密高强低介电的多孔氮化硅材料。采用有机涂层对多孔氮化硅材料表面进行封孔处理,通过对封孔前后材料电性能的对比分析得出:涂层对封孔后表面致密的整体材料电性能影响微小。     

Ferroelectric-Domain Structure in Piezoelectric Ceramics

Twin-related (tetragonal (T), rhombohedral (R)) adjacent ferroelectric domains, which require a smaller energy for the rotation of the polarization vector, have been found to occur in lead zirconate titanate type piezoceramics at the morphotropicphase boundary, explaining the triplet splitting observed in electron diffraction patterns. The values of elastically stored energy density in the walls of the twinning domains are estimated, and a packing model of the ferroelectric domain structure as a T₁RT₂RT₁…succession is proposed to explain the coexistence of the two ferroelectric phases in the morphotropicphase boundary region. A crystallographic analysis of the transformation from the paraelectric to the ferroelectric phase is performed on the basis of martensite transformation theory. The calculated results are in good agreement with the observed transmission electron microscopy data. In particular, the crystallography and morphology of the "herringbone" domain structure, often observed in piezoelectrio ceramics, are well explained by this analysis.     

(1-x)BaTiO3-xKNbO3陶瓷的制备及性能研究

采用复合溶胶凝胶法制粉技术结合传统陶瓷制备工艺,制备了(1-x)BaTiO_3-xKNbO_3陶瓷,对其晶相特征、介电及压电铁电性能进行了研究。在1250℃下烧结的陶瓷形成了单一相的钙钛矿结构固熔体。介电常数随着KNbO_3含量的增加先减小后增加,KNbO_3的加入降低了陶瓷的介电损耗。样品的居里温度也在120℃之间波动。KNbO_3的加入使样品的压电常数d_33值逐渐减小。样品BT的d_33值最大,为140pC/N。样品的剩余极化强度(Pr)随着KNbO_3含量的增加而减小,由7μC/cm~2降为3μC/cm~2;矫顽场强(EC)随KNbO_3含量的增加呈现出变小的趋势,样品BT-KN10的矫顽场强(E_C)为4kV/cm。     

Effect of Firing Cycle on Structure and Some Dielectric and Piezoelectric Properties of Barium Titanate Ceramics

In the preparation of barium titanate ceramics for dielectric and piezoelectric applications, careful attention must be given to many factors which determine the ultimate performance of the ceramic. In this study structural differences were observed with the aid of electron micrographs as the time and temperature of firing were varied. At lower temperatures and shorter firing intervals crystals remained small, grain-boundary areas were relatively large, and there were numerous voids where several crystals joined. As the time and/or temperature were increased, crystals became larger with an improved grain-boundary condition that resulted in better structure. An optimum condition was soon reached beyond which rounding of edges at grain boundaries where several crystals joined became more pronounced. This caused an increase in the number of voids. Accompanying these changes, the 1-kc. dielectric constant, the piezoelectric constants (thickness mode), and coupling coefficients first improved, reached optimum values, and then declined slightly, but the resistance to depoling continually decreased as the crystal size increased. An experimental technique of rapid heating and cooling was used to prepare dense specimens of chemically pure barium titanate with relatively small average crystal sizes. Dielectric constants as high as 3000 with Q values of 80 were obtained for these high-density ceramics, accompanied by low effective piezoelectric constants and coupling coefficients.     

多孔低介电氧化硅陶瓷材料的制备

采用氧化硅为原料,木屑作为造孔剂制备了多孔的氧化硅陶瓷材料。借助于气孔率测试、抗弯强度测试、介电性能测试和SEM测试手段分析了造孔剂和烧结助剂的添加量对材料性能的影响。结果表明:加入BN作为添加剂烧成的氧化硅抗弯强度最大可达到14.80MPa。加入木屑作为造孔剂制备的陶瓷可以形成明显的气孔,气孔率最高可达到48.40%,介电常数最低可以达到3.0。     

高介电常数微波介质陶瓷的发展及研究现状

对高介电常数微波介电陶瓷中的BaO-Ln2O3-TiO2、复合钙钛矿CaO2-Li2O2-Ln2O3-TiO2及铅基钙钛矿体系的发展及研究现状进行了概述,归纳了研究中存在的问题,同时对未来的发展趋势做了预测.对新型填满型钨青铜结构陶瓷也进行了简要的介绍,指出其具有良好的发展前景,但其介电弛豫性需要进一步的研究.