AgNbO3-BaTiO3陶瓷在准同型相界附近的电学性能研究

最近的理论工作预期，可能存在一种新的无铅压电陶瓷xAgNbO3-（1-x）BaTiO3，认为在含12％AgNbO3的组分处存在准同型相界（MPB），具有良好的性能，并有较高的居里点。但是尚未见到有关这方面的实验报道。通过传统的固相反应法合成xAgNbO3-（1-x）BaTiO3陶瓷，其中取x等于0．08到0．16。首先在950℃下预烧3h合成AgNbO3-BaTiO3，然后将粉末球磨、压片后，在1150℃下进一步烧结得到样品。通过X射线衍射技术（XRD），研究了xAgNbO3-（1-x）BaTiO3的相结构，并对这一体系的电学性质进行了测试。发现x=0．12附近存在着MPB，且介电常数达到1000左右，剩余极化强度达到3．5μC／cm^2，矫顽场反为800V／mm。xAgNbO3-（1-x）BaTiO3作为一种可供选择的无铅压电陶瓷值得进一步的研究和开发。     

PMN-PZN-PT铁电陶瓷的准同型相界及电学性能

基于准同型相界(morphotropic phase boundary, MPB) 线性组合规律,研究Pb(Mg_(1/3)Nb_(2/3))O_3 -Pb(Zn_(1/3)Nb_(2/3))O_3-PbTiO_3 (PMN-PZN-PT)三元系的MPB区域,并探求电学性能优越的组分.实验选取(1-x) (0.67 PMN- 0.33 PT)-x(0.91 PZN-0.09 PT) 系列中x=0～0.85的8个实验点;为减少焦绿石相的生成,陶瓷试样用铌铁矿预产物法合成,最终在1120～1160 ℃烧成.X射线衍射分析表明该系列试样均为钙钛矿结构,且处于四方与菱方两相共存态,验证了两个子二元系MPB组分的连线均为该三元系的MPB区域.少量的PZN-PT取代PMN-PT可以提高该三元系的电学性能;在x=0.1的组分获得该系列的最优性能:极值介电常数ε_(m,1 kHz)=28 030,剩余极化强度Pr=32.5 μC/cm~2,压电系数d_(33)=545 pC/N.     

准同型相界附近PLZT铁电陶瓷相变的原位Raman谱观测

对Zr与Ti的原子比约为52/48,掺杂了少量La、Mn和Nb的PLZT铁电陶瓷进行了不同温度下的原位Raman谱观测,对所获得的谱图进行温度分布修正,再利用阻尼-谐振-振荡器模型的光谱响应函数及Gauss分布函数对所得结果进行分峰拟合,得到了各Raman峰的波数和峰强随温度的变化规律.结果表明,准同型相界附近的PLZT铁电陶瓷在47-600℃升温过程中,于240和360℃分别发生两次相变,表明样品中可能存在混合相;通过比较未极化和极化样品的Raman谱峰的变化结果,分析了预极化处理对相变的影响.     

（Bi0．5Na0．5）TiO3-（Bi0．5K0．5）TiO3陶瓷在准同型相界附近的铁电和压电性能

通过传统的固相烧结法合成（1-x）（Bi0.5Na0.5）TiO3-x（Bi0.5K0.5）TiO3陶瓷（x选取范围0．135-0．24）。先在850℃合成原料粉体，然后在1100～1200℃下烧结得到陶瓷样品。分析检测该体系陶瓷的结构以及铁电、压电性能。x射线衍射分析结果表明，该二元系准同型相界（MPB）区域位于x=0．165～0．225附近。对这一体系铁电和压电性能进行测试，并对其在准同型相界附近的电学性能发生变化的机理作了讨论。（Bi0．5Na0．5）TiO3-（Bi0.5K0.5）TiO3是一种很有应用前景的无铅压电陶瓷材料，值得进一步的研究和探索。同时，本实验还对密封烧结工艺对无铅压电陶瓷性能的影响作了初步的研究。     

传统工艺制备铌酸钾钠基无铅压电陶瓷的性能控制

介绍了采用传统陶瓷制备工艺,为获得晶粒细小、组织致密、性能良好的铌酸钾钠基无铅压电陶瓷,目前所采取的性能控制措施,即添加助烧剂、掺杂改性、添加第二组元、准同型相界的研究及调整n(Na)/n(K),来调整NKN陶瓷的性能。展望了NKN基无铅压电陶瓷的发展趋势。     

BNT-BZT压电陶瓷准同相界处材料性能的研究

研究(1-x)(Bi0.5Na0.5)TiO3-xBa(Ti0.95Zr0.05)O3(BNT-BZT)体系陶瓷的准同型相界,以及陶瓷材料的微观结构和性能之间的关系.BNT-BZT陶瓷体系在富BNT和Zr含量低的区域存在准同型相界,在相界附近可能得到性能优良的无铅压电陶瓷,相界点在x≈0.1这个区域内.将BNT陶瓷和BZT陶瓷固溶后能够得到d33大于150 pC/N,居里温度在240℃左右,介电常数在900左右的性能良好的无铅压电陶瓷.     

PMN-PT弛豫铁电陶瓷的低温烧结与压电性能

以LiF为烧结助剂研究了PMN-PT 68/32弛豫铁电陶瓷的低温烧结和压电性能.结果表明LiF烧结助剂完全固溶到PMN-PT陶瓷中形成具有复合钙钛矿结构的固溶体,无任何第二相存在.添加2.5%LiF烧结助剂可以使PMN-PT压电陶瓷的烧结温度从1250℃降到1000℃,而且该试样具有致密均匀的显微结构,其体积密度为7.87g/cm3,达理论密度的95%,其平面机电耦合系数为71%,压电常数为500pC/N左右,最大应变量达0.25%左右.     

Pb[(Mg1/3Nb2/3)0.536(Ni1/3Nb2/3)0.128Ti0.336]O3陶瓷的结构和电学性能

通过铌铁矿预产物法制备出了Pb[(Mgq/3Nb2/3)0.536(Ni1/3Nb2/3)0.128Ti0.336]O3铁电陶瓷,并对其结构和电学性能进行了研究.结果表明,该三元体系组成处在准同型相界区域,1kHz时的介电常数极值达到45540,剩余极化强度为37uC/gm2,压电系数d33也达到780pC/N.烧结时有效地抑制PbO的挥发对于获得高性能的铅系铁电陶瓷有决定性的影响.     

烧结温度对PMN-PNN-PZT四元系压电陶瓷微观结构和压电性能的影响

选取PMN-PNN-PZT四元系压电陶瓷准同型相界附近配方,采用传统的氧化物混合合成工艺制备压电陶瓷材料.研究了不同烧结温度对该四元系压电陶瓷微观结构和压电性能的影响,研究结果表明在1180℃烧结时,晶粒生长很好,晶界处结合致密,压电性能也最好d33=475pC/N,ε33T/ε0=3203, Qm=82,Kp=0.59,tanδ=1.8%.     

(1-x)K0.5Na0.5NbO3-xLiBiO3无铅压电陶瓷的结构与压电性能（英文）

采用传统固相反应制备了(1-x)(K0.5Na0.5)NbO3–xLiBiO3[(1–x)KNN–xLB](x=0,0.0005,0.001,0.002,0.004,0.006,0.008,0.010)压电陶瓷,并分析研究了其微结构及电性能。结果表明,LB 掺杂的 KNN 陶瓷主要形成了钙钛矿结构,没有检测到第二相的存在,并且陶瓷的相结构出现直接由正交相过渡到立方相的"反常"转变;随着LB 掺杂量的增加,晶粒尺寸逐渐细化,陶瓷的压电常数d33、平面机电耦合系数kp先略有增加后显著下降,且分别在x=0.002和 x=0.001时达到最大值,分别为115pC/N和0.2701;陶瓷的介电常数εr随x增大先增加后略有降低,当 x=0.006时获得最大值,为871.8。     

Effects of CeO2 doping on the structure and properties of PSN-PZN-PMS-PZT piezoelectric ceramics

Quinary system piezoelectric ceramics PSN-PZN-PMS-PZT were prepared by using a two-step method. The effects of CeO2 doping on piezoelectric and dielectric properties of the system were investigated at morphotropic phase boundary （MPB）. The results reveal that the relative dielectric constant ε33^T｜ε0, the Curie temperature To, the piezoelectric constant d33, the mechanical quality factor Qm, and the electromechanical coupling coefficient Kp are changed with the increase of CeO2 content. On the other hand, the effects of CeO2 doping on the dielectric properties of PSN-PZN-PMS-PZT piezoelectric ceramics at high electric field are consistent with the change at weak electric field. The values of dielectric constant and dielectric loss are enhanced with the increasing of electric field.     

先驱体合成法制备PMN-PT弛豫铁电体及其表征

采用先驱体合成法,以氧化物为原料制备了钙钛矿结构的(1-x)PMN—xPT弛豫铁电陶瓷粉末,研究了预烧温度以及PbTiO3固溶量等工艺参数对样品的相结构的影响．结果表明,随预烧温度升高,PMN—PT钙钛矿相含量增加,但温度过高,由于PbO的挥发钙钛矿相又减少;增加PbTiO3也可使钙钛矿相含量增加．     

Effect of sintering temperature and composition on microstructure and properties of PMS-PZT ceramics

The piezoelectric ceramics xPb（Mn1/3Sb2/3）O3-（1-x）Pb（Zr1/2Ti1/2）O3 （abbreviated as PMS-PZT） were synthesized by traditional ceramics process. The effect of sintering temperature and the amount of Pb（Mn1/3Sb2/3）O3 （abbreviated as PMS） on phase structure, microstructure, piezoelectric and dielectric properties of PMS-PZT ceramics was investigated. The results show that the pure perovskite phase is in all ceramics specimens, the phase structure of PMS-PZT ceramics changes from tetragonal phase to single rhombohedral phase with the increasing amount of PMS. The dielectric constant εr, Curie temperature Tc, electromechanical coupling factor kp and piezoelectric constant d33 decrease, whereas the mechanical quality factor Qm and dielectric loss tanδ increase with the increasing amount of PMS in system. The optimum sintering temperature is 1 200-1 250 ℃. It is concluded that the PMS-PZT （x=0.07） ceramics sintered at 1 250 ℃ is suitable for high-power piezoelectric transformer. These properties include εr=674.8, tanδ =0.005 25, kp=0.658, Qm= 1 520, d33=230 pC/N, Tc=275 ℃.     

Characterization and piezoelectric thermal stability of PIN–PMN–PT ternary ceramics near the morphotropic phase boundary

The phase structure and piezo/dielectric properties of xPb(In_1/2Nb_1/2)O₃–yPb(Mg_1/3Nb_2/3)O₃–zPbTiO₃ (PIN–PMN–PT x/y/z) ternary ceramics with morphotropic phase boundary (MPB) composition were investigated. It was found that Curie temperatures of choosing composition changed from 165 °C to 293 °C and the piezoelectric properties are almost the same at room temperature in PIN–PMN–PT system near MPB. The piezoelectric coefficient d₃₃ and electromechanical coupling factor k_p are higher than 440 pC/N and 60%, respectively. Temperautre and dc bias dependence of piezoelectric response for PIN–PMN–PT ceramics were measured. The usage temperature range was found to be improved, compared with PMN–PT single crystal near MPB.     

Influence of Sb<Subscript>2</Subscript>O<Subscript>3</Subscript> doping on the properties of KBT-NBT-BT lead-free piezoelectric ceramics

0.144(K0.5Bi0.5)TiO3-0.85(Na0.5Bi0.5)TiO3-0.006BaTiO3(KBT-NBT-BT) lead-free piezoelectric ceramics were prepared using a conventional solid state method.The influence of Sb2O3 doping on the crystal phase,surface microstructure and properties of the KBT-NBT-BT lead-free piezoelectric ceramics were investigated using X-ray diffraction(XRD),scanning electron microscope(SEM) and other analytical methods.The results show that all compositions are of pure perovskite structure solid states.Sb2O3 doping does not influence the microstructure of KBT-NBT-BT lead-free piezoelectric ceramics obviously in the Sb2O3 doping range of 0.1-0.5 wt.%.Sb2O3 functions as a donor when doped small amount,while functions as a acceptor when doped large amount.The piezoelectric strain constant(d33) increases first and then decreases;the dielectric constant(ε3T3/ε0) and the dielectric loss(tanδ) decrease continuously when the amount of Sb2O3 dopant increases.When the doping amount of Sb2O3 is 0.1 wt.%,the KBT-NBT-BT piezoelectric ceramics with good comprehensive properties are obtained,whose d33,ε3T3/ε0 and tanδ are 147 pC/N,1510 and 4.2%,respectively.     

Theoretical modeling of coexisting tetragonal and rhombohedral heterophase polydomain structures in lead zirconate titanate ferroelectric films near the morphotropic phase boundary

The coexistence of tetragonal and rhombohedral phases as elastic domains is studied in this paper for lead zirconate titanate (PZT) ferroelectric films near the morphotropic phase boundary (MPB). The volume fractions of the phases and different twin components are obtained as functions of misfit strain and film orientation. It is shown that the superior electromechanical properties of MPB-PZT films may be understood on the basis of a field-induced evolution of the heterophase polydomain structure.     

Effects of Cr2O3 doping on the electrical properties and the temperature stabilities of PZT binary piezoelectric ceramics

The ceramics with Pb1.04Zr0.52Ti0.48O3 + z wt.% Cr2O3 were prepared using the traditional technique.The effects of Cr2O3 doping on the phase structure,the microstructure,and the electrical properties of ceramics were investigated.Meanwhile,the temperature stabilities of the resonant frequency (fr) were studied.The results showed that the △fr/fr,25℃ decreased with the addition of 0.2 wt.% - 0.8 wt.% Cr2O3 as compared with the undoped samples.The minimum value (-0.182%) of △fr/fr,25℃ was obtained for z = 0.6 wt.% Cr2O3 samples that sintered at 1260℃.The values of εT33/ε0 = 1650,tanδ = 0.006,d33 = 328 pC/N,Kp= 0.63,Qm = 2300 were obtained when Cr2O3 was 0.6 wt.%,which exhibited more excellent piezoelectric properties than other compositions such as those with z = 0.2 wt.%,0.4 wt.%,and 0.8 wt.%,but had a similar value as compared with the undoped samples.When the Cr2O3 additive increased,the Curie temperature moved toward low temperature and the changes of resonant frequency changed from positive to negative with increasing temperature.     

高居里点BiScO3-PbTiO3压电陶瓷介电压电性能研究

用通常的固相反应法制备了(1–X)BiScO3-XPbTiO3(X=0.60,0.62,0.64,0.66,0.68)系压电陶瓷,并对其进行了微结构和介电、压电性能研究。XRD分析表明,该系统在PbTiO3摩尔分数X=0.64时,存在准同相界,当X小于0.64或大于0.64时,陶瓷分别为菱方相和四方相结构。相结构在准同相界的试样具有最大的压电常数,其d33高达430pC/N。介温谱测试表明,该陶瓷体系居里温度为450℃左右,具有弛豫铁电体特征。     

Dielectric properties and point defect behavior of antimony oxide doped Ti deficient barium strontium titanate ceramics

The microstructures and dielectric properties of Sb₂O₃-doped Ti deficient barium strontium titanate ceramics prepared by solid state method were investigated with non-stoichiometric level and Sb₂O₃ content by SEM, XRD and LCR measure system. It is found that with the increase of δ, (Ba_0.75Sr_0.25)Ti_1–δO_3–2δ ceramics transform from single phase solid solutions with typical cubic perovskite structure to multiphase compounds while (Ba_0.75Sr_0.25)Ti_0.998O_2.996 ceramics remain to be single-phase with the increasing Sb₂O₃ content. The distortion of the ABO₃ perovskite lattice caused by V_Ti″″ and V_o^?? induces the drop of Curie temperature and the rise of relative dielectric constant in (Ba_0.75Sr_0.25)Ti_1–δO_3–2δ ceramics with increasing δ value. The orientation of V_o^?? elastic dipoles results in the domain-wall pinning and thus the reduction of the dielectric loss. With increasing Sb₂O₃ content, the relative dielectric constant, dielectric constant maximum and Curie temperature of (Ba_0.75Sr_0.25)Ti_0.998O_2.996 ceramics decrease dramatically while the dielectric loss increases.     

镨掺杂PZT二元系压电陶瓷性能研究

以固态氧化物为原料，采用传统方法制备错掺杂PZT压电陶瓷。通过XPS，XRD以及SEM方法分析组成为Pb1-1．5xPbZr0．54Ti0．46O3（x=0．02～0．08）压电陶瓷的元素价态，相组成以及显微结构。结果发现：合成温度900℃，可以得到钙钛矿结构。在镨掺杂为3mol％的准同型相界附近三方相和四方相并存，综合性能达最佳值：E33^T／ε0=2000，d33=418pC/N，Kp=52．9％，Qm=75。随着镨掺杂量的增加，Pr-PZT陶瓷的居里温度降低。