锰掺杂对PNW-PMS-PZT压电陶瓷结构和性能的影响

采用传统陶瓷工艺制备了Pb(Ni1/2W1/2)O3-Pb(Mn1/3Sb2/3)O3-Pb(Ti，Zr)O3-xMnO2压电陶瓷，分析了经1150℃烧结2h制备的陶瓷样品的相结构组成。实验结果表明：所有陶瓷样品均为钙钛矿相，未发现其它晶相。随着锰掺杂量的增加，陶瓷晶粒逐渐长大。研究了不同剂量的锰掺杂对压电陶瓷介电和压电性能的影响。结果表明：随着锰掺杂量的增加，材料逐渐变“硬”，当MnO2掺杂量少于0．2％(按质量计，下同)时，相对介电常数εr、压电常数d33和机械品质因数Qm逐渐增加，介电损耗tanδ减小；当MnO2掺杂量多于0．2％时，εr、d33和Qm逐渐降低，tanδ增加。随着锰掺杂量的增加，机电耦合系数kp和Curie温度θc逐渐减小。MnO2掺杂量为0．2％的压电陶瓷适合制作大功率压电陶瓷变压器。其压电性能为：εr=2138，tanδ=0．0058，kp=0．613，Qm=1275，d33=380pC／N和θc=205℃。     

(K_(0.485)Na_(0.485)Li_(0.03))NbO_3-Pb(Zr_(0.53)Ti_(0.47))O_3压电陶瓷的压电性能与微观结构

采用传统电子陶瓷制备技术和工业原料制备了新型(1-x)(K0.485Na0.485>Li0.03)NbO3-Pb(Zr0.53Ti0.47)O3少铅压电陶瓷,研究了该体系陶瓷的压电性能及微观结构.X射线衍射分析表明:在1250℃烧结3h的条件下,所有陶瓷样品都具有纯的钙钛矿结构和高致密性,并且在室温下形成了正交相和四方相共存的结构.x=0.75时,陶瓷的压电性能达到最佳:压电常数d33=363 pC/N,机电耦合系数kp=63%,相对介电常数εr=1 590,介质损耗tanδ=1.70%.     

微波水热法制备(1-x) K0.55Na0.45NbO3-xLiSbO3系无铅压电陶瓷

以分析纯NaOH,KOH,Li2CO3,Nb2O5,Sb2O3等为原料,采用微波水热法合成(1-x)K0.55Na0.45NbO3-xLiSbO3(KNNLS,x =0.03～0.07mol)粉体,分析了粉体的晶体结构与形貌.以该粉体制备压电陶瓷,系统研究了LiSbO3含量对压电陶瓷结构与性能的影响.研究结果表明:微波水热法在220℃下保温30min可以合成具有纯正交钙钛矿结构的KNNLS(x=0.03～0.07)粉体,粉体呈立方状,尺寸约0.5～1μm.利用该粉体制备的压电陶瓷结构致密,晶粒大小分布均匀.当x=0.05时,该组成陶瓷具有最佳的综合压电性能:压电常数d33=110 pC/N,平面机电耦合系数kp=0.29,介电常数εT33/ε0=466,介质损耗tanδ =1.4％以及机械品质因素Qm=107.     

锂掺杂KNN-BNKT无铅压电陶瓷性能研究

采用液相包覆法制备了结构致密的铌酸钾钠基[(K0.5Na0.5NbO3-K0.1Na0.4Bi0.5TiO3)-xLiNbO3,0≤x≤0.02]无铅压电陶瓷,研究了掺杂Li+对铌酸钾钠钛酸铋钾钠K0.5Na0.5NbO3-K0.1Na0.4Bi0.5TiO3(KNN-BNKT)晶体结构和压电、介电性能的影响。结果表明:当Li+含量在x取0～0.010(摩尔分数)时,陶瓷样品均形成了均一的钙钛矿型结构。Li+掺杂量对陶瓷压电、介电性能有很大的影响,其压电常数(d33)随着Li+掺杂量的增加先升高后降低,并在x=0.010的时候取得最大值。实验表明:当x=0.01时,(K0.5Na0.5NbO3-K0.1Na0.4Bi0.5TiO3)-xLiNbO3无铅压电陶瓷表现出较好的压电性能:d33=173pC/N,相对介电常数εr=620.745,介电损耗tanδ=0.0132,kp=27.35%,kt=26.34%,Qm=48.97。     

锂盐助烧铌镁酸铅-钛酸铅陶瓷的压电性能

采用铌铁矿预产物合成法制备了锂盐[碳酸锂(Li2CO3),硝酸锂(LiNO3),氟化锂(LiF)]助烧0.68Pb(Mg1/3No2/3)O3-0.32PbTiO3(PMN-PT68/32)弛豫铁电陶瓷.用X射线衍射分析陶瓷相组成并测试PMN-PT68/32的压电性能.结果表明:所有陶瓷样品均为纯钙钛矿相.无任何其它杂相.添加Li2CO3和LiNO3可以使PMN-PT68/32陶瓷压电性能有一定提高.添加LiF可以使PMN-PT68/32陶瓷压电性能提高很多,其中1150℃烧结添加LiF样品的压电性能为:平面机电耦合系数(kp)约为64%;厚度机电耦合系数(kt)约为54%t压电常数(d33)约为623pC/N;机械品质因数(Qm)约为96.添加Li2CO3和LiNO3样品只发生Li 在PMN-PT68/32的B位置换并产生氧空位.添加LiF样品可以通过F-取代反应产生铅空位来补偿Li 取代产生的氧空位.因此,LiF作为助烧剂的PMN-PT68/32陶瓷的优良压电性能不仅源于低温液相烧结以及阳离子Li 的取代,而且很大程度上源于阴离子F-的取代.     

高Curie温度(1-2x)PbNb2O6-xSrTiO3-xTiO2压电陶瓷

采用传统电子陶瓷的制备方法制备了(1-2x)PbNb2O6-xSrTiO3-xTiO2(x=0.005～0.025)高Curie温度(θc)压电陶瓷.X射线衍射分析表明:所有样品在1 250℃保温2h烧结均形成铁电性的斜方钨青铜型结构(tungsteu bronze structure,TB).相对介电常数-温度(εr-θ)曲线表明:该体系具有高的θc(500～560℃).测试了不同掺杂量对陶瓷介电和压电性能的影响,发现材料的θc、压电常数(d33)和机电耦合系数(κp)随着x值的增加先增加后降低.当x=0.02时,陶瓷的d33达到最大值,为83pC/N,θc为550℃,κp达33.4%,材料的介电常数Εθ33/ε0为217,为组成的最优配方.     

氧化铋掺杂对铌酸钾钠无铅压电陶瓷性能的影响

用传统固相反应法制备了结构致密的铌酸铋钾钠[(Na0.5K0.5)1-3xBixNbO3,0≤x≤0.05]无铅压电陶瓷,研究了掺杂氧化铋(Bi2O3)对铌酸钾钠(Na0.5K0.5)NbO3(NKN)晶体结构和压电性能的影响.结果表明:当Bi2O3含量x＜0.02时,能得到具有纯钙钛矿结构的(Na05K0.5)1.3xBixNbO3陶瓷.最佳烧结温度随Bi2O3含量的增加而升高,与纯铌酸钾钠陶瓷相比,样品密度显著提高.Bi2O3掺杂量对铌酸钾钠的压电性能有很大影响,其压电常数(d33),机电耦合系数(kp,kt)随Bi2O3含量的增加先升高而后降低,并在x=0.01时达到最大值,机械品质因数(Qm)有明显提高.实验表明:当x=0.01时,(Na0.5K0.5)1-3BixNbO3无铅压电陶瓷的密度达4.42g/cm3,表现出优异的压电性能:d33=154×10-6C/N,kp=45%,kt=46%,介电损耗tanδ=3.5%,相对介电常数ε=598,Qm=138.     

(K_(0.5)Na_(0.5))NbO_3-CaZrO_3基无铅压电陶瓷的相结构和压电性能研究

采用传统陶瓷工艺制备了(1-x)(K0.5Na0.5)NbO3-xCaZrO3(简称KNN-CZ)无铅压电陶瓷。分析了陶瓷样品的相结构组成。测试结果表明:所有陶瓷样品均为钙钛矿相,未发现其它晶相。随着CaZrO3含量的增加,(1-x)KNNxCZ陶瓷的相结构由正交相转变为四方相,最后变为立方相。研究了不同CaZrO3含量对压电性能的影响,实验表明:当CaZrO3含量为0.05mol时,压电常数d33和径向机电耦合系数kp分别达到了最大值196pC/N和0.35。(1-x)KNNxCZ(x=0.05)陶瓷的压电性能展现了良好的温度稳定性和经时稳定性,这些结果表明(1-x)KNN-xCZ(x=0.05)陶瓷是一种优良的无铅压电备选材料。     

制备工艺对铌锑-锆钛酸铅系压电陶瓷性能的影响

由Nb5+,Sb3+置换锆钛酸铅的B位离子,制备了用作大功率水声换能器材料的铌锑-锆钛酸铅系压电陶瓷.采用固相法合成了0.02Pb(Sb1/2Nb1/2)O3-0.98PbZr1-xTixO3(x=0.44～0.49)粉体.通过X射线衍射及扫描电镜分析.研究了不同锆钛比和烧结温度对陶瓷的相组成、显微结构和介电、压电性能的影响.结果表明:当合成温度为900℃时,获得的粉体的主晶相为钙钛矿结构.当Zr/Ti摩尔比为51/47,烧结温度为1230℃时,各项性能达到最佳值,介电常数ε T 32/ε0为1945,介电损耗tanδ为0.019,压电常数d33为425pC/N,机电耦合系数Kp为0.65,Curie温度θc为352℃.铌锑-锆钛酸铅系压电陶瓷的烧结温度范围宽,具有较强的工艺操作性且θc高.     

锰锑酸铅-锌铌酸铅-锆钛酸铅陶瓷的压电性能

以同时位于准同型相界的Pb(Mn1/3Sb2/3)0.05(Zr1/2Ti1/2)0.95O3(PMnS-PZT)与Pb(Zn1/3Nb2/3)0.28(Zr1/2Ti1/2)0.72O3(PZN-PZT)组合而成的xPb(Mn1/3Sb2/3)0.05(Zr1/2Ti1/2)0.95O3-(1-x)Pb(Zn1/3Nb2/3)0.28(Zr1/2Ti1/2)0.72O3[xPMnS-(1-x)PZN]四元系压电陶瓷为研究对象,研究了PZN和PMnS含量的变化对xPMnS-(1-x)PZN材料结构与性能的影响,制备了具有高性能的四元系xPMnS-(1-x)PZN陶瓷材料.结果表明:性能最好的组成位于准同型相界附近靠近四方相含量较高的区域.Ba2 ,Sr2 取代显著提高了材料的压电性能,Ba2 取代0.5PMnS-0.5PZN的性能为压电系数da3=406 pC/N,机电耦合系数kp=0.55,介电常数εT33/ε0=2 183,机械品质因数Qm=1 077和介电损耗tan δ=2.7%;Sr2 取代0.6 PMnS-0.4 PZN的性能为d33=438 pC/N,kp=0.55,εT33/ε0=2 701,Qm=1 073和tan δ=3.3%.     

Preparation of Dense Lead Magnesium Niobate–Lead Titanate (Pb(Mg1/3Nb2/3)O3–PbTiO3) Ceramics by Spark Plasma Sintering

The effect of spark plasma sintering (SPS) on the densification behavior of Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ ceramics has been investigated. Specimens with a density of >99% of the theoretical density (TD) were obtained using SPS treatment at 900°C. Through normal sintering at 1200°C, however, the density of the specimen was only ∼92% of TD.     

PMN-PT系统中偏置电场诱导压电效应的研究

通过测定PMN-PT系统中不同PT含量时的介温谱、电滞回线和偏置电场诱导下的压电性能探讨了(1-x)PMN-xPT系统(x=0～0.4))的组成、结构与性能之间的关系.实验结果表明,当x＜0.07时,PMN-PT材料表现为典型的弛豫铁电体;当0.07＜x＜0.13时,材料具有弛豫铁电体为主的过渡型结构;当0.13＜x＜0.33时,具有普通铁电体为主的过渡型结构;当x=0.33～0.34时,材料位于准同型相界,而当x＞0.34,PMN-PT则表现为普通铁电体.     

弛豫型铁电体Pb(B1/3Nb2/3)O3基复合陶瓷中两相共存的研究

在ＰＺＮ－ＢＴ,ＰＭＮ－ＢＴ－ＰＴ和ＰＮＮ－ＰＴ系统中,用两相混合烧结法,分别制备了ＰＺＮ基,ＰＭＮ基和ＰＮＮ基复合陶瓷,介电性能测试结果表明,ＰＺＮ基陶瓷为两相共存的复相陶瓷,而ＰＭＮ基和ＰＮＮ基陶瓷中的两相都发生了很大程度的固溶,应用键价理论和键性分析对此进行了讨论,并从两组元间扩散动力这的角度和显微结构特征对这一现象进行了分析。     

Composition and temperature dependence of structure and piezoelectricity in (1−x)(K1−yNay)NbO3‐x(Bi1/2Na1/2)ZrO3 lead‐free ceramics

Lead‐free piezoceramics with the composition (1?x)(K_1?yNa_y)NbO₃‐x(Bi_1/2Na_1/2)ZrO₃ (KNyN‐xBNZ) were prepared using a conventional solid‐state route. X‐ray diffraction, Raman spectroscopy, and dielectric measurements as a function of temperature indicated the coexistence of rhombohedral (R) and tetragonal (T) phase, typical of a morphotropic phase boundary (MPB) as the BNZ concentration increased and by adjusting the K/Na ratio. High remnant polarization (P_r=24 μC/cm²), piezoelectric coefficient (d₃₃=320 pC/N), effective piezocoefficient ({d_{33}^*}=420 pm/V), coupling coefficient (k_p=48%), and high strain (S=0.168%) were obtained at room temperature, but significant deterioration of P_r, {d_{33}^*}, and k_p were observed by increasing from room temperature to 160°C (17.5 μC/cm², 338 pm/V, and 32%, respectively) associated with a transition to a purely T phase. Despite these compositions showing promise for room‐temperature applications, the deterioration in properties as a function of increasing temperature poses challenges for device design and remains to be resolved.     

Fabrication of PMN and PFN ceramics by a two-stage sintering technique

Relaxor perovskite ceramics of lead magnesium niobate (PMN) and lead iron niobate (PFN) have been prepared by employing a two-step mixed oxide synthetic route, followed by the application of a two-stage sintering method. The effect of the latter on phase formation, densification behaviour, microstructure and dielectric properties of both relaxor systems is examined. Two types of pyrochlore phase are found to co-exist with the major phase in the PMN system, i.e. Pb₃Nb₄O₁₃ and Pb_1·83Nb_1·71Mg_0·29O_6·39 with an MgO inclusion. By comparison, a PbFe₈O₁₃ pyrochlore phase with an Fe₂O₃ inclusion is observed in the PFN system. The types and concentrations of phases present are found to depend upon sintering conditions. In connection with dielectric properties, a substantial dependence of the maximum values of both relative permittivity (′_r,max) and dissipation factor (tanδ_max) on sintering regime is observed. By employing optimised two-stage sintering conditions, high density ceramics with low firing temperatures and reasonable relative permittivities can be achieved in both systems.     

B位离子的差异对铅系弛豫铁电体复合陶瓷中两相共存的影响

用两相混合烧结法分别制备Ｐｂ（Ｚｎ１／３Ｎｂ２／３）Ｏ３系和Ｐｂ（Ｎｉ１／３Ｎｂ２／３）Ｏ３系复合陶瓷,介电性能测试结果表明,Ｐｂ（Ｚｎ／３Ｎｂ２／３）Ｏ３系陶瓷材料中保持了两相共存的复相结构,而Ｐｂ（Ｎｉ１／３Ｎｂ２／３）Ｏ３系陶瓷材料中却难以获得两相共存的复相结构,从晶体化学和扩散动力学的角度对这一结果进行了分析。     

Co-firing of PZN-PZT Flextensional Actuators

Flextensional actuators composed of a piezoelectric PZN-PZT layer and a conducting PZN-PZT/Ag layer were fabricated. Because the newly developed PZN-PZT was sinterable at low temperature (<900°C), silver particles could be co-fired with the PZN-PZT. Therefore, an electrically conducting PZN-PZT/Ag layer was fabricated by mixing the silver particles with PZN-PZT powder. When 30–50 wt% Ag particles were mixed with the PZN-PZT, the resulting composites showed a high-electrical conductivity and low-densification mismatch with respect to the PZN-PZT layer. The PZN-PZT/Ag layer had approximately the same resistivity as pure silver, because of the presence of a conducting channel of dispersed silver particles in the PZN-PZT matrix. Two- and three-layered actuators were fabricated with a diameter of 20 mm and a thickness of 0.9 mm using these PZN-PZT and PZN-PZT/Ag composites. When an electric field was applied, the fabricated actuators bent into a convex dome shape, yielding a large axial displacement at the center.     

Influence of Excess PbO Additions on {111} Single-Crystal Growth of Pb(Mg1/3Nb2/3)O3–35 mol% PbTiO3 by Seeded Polycrystal Conversion

The influence of additions of excess PbO to Pb(Mg_1/3Nb_2/3)O₃–35 mol% PbTiO₃ (PMN–35PT) on {111} single-crystal growth by seeded polycrystal conversion was studied in the range of 0–5 vol% PbO. PbO volatilization and hence weight loss during annealing was controlled effectively by a double-crucible type of arrangement. PbO additions increased boundary mobility significantly in PMN–35PT, thus facilitating single-crystal growth by seeded polycrystal conversion (SPC). This is attributed to the formation of a boundary wetting PbO-based liquid phase. The growth process occurs very rapidly initially, after which it slows down. This is presumably due to both a decrease in the driving force for boundary migration because of an increase in matrix grain size, and a transition to lower mobility facets. It is also shown that for a given annealing time, the size of the grown crystal scales with the lateral dimensions of the seed crystal.