PbZrO3含量对PZN-PZ-PT固溶体弥散性相变的影响

报道了相界附近PZN-PZ-PT三元系固溶体弥散性相变,并研究了PbZrO3含量对PZN-PZ-PT固溶体弥散性相变的影响,发现随着PbZrO3含量的增加,PZN-PZ-PT固溶体弥散程度有所增加.     

PbZrO3含量对PZN-PZ-PT因溶体弥散性相变的影响

报道了相界附近ＰＺＮ－ＰＺ－ＰＴ三元系固溶体弥散性相变,并研究了ＰｂＺｒＯ３含量对ＰＺＮ－ＰＺ－ＰＴ固溶体弥散性相变的影响,发现随着ＰｂＺｒＯ３含量的增加,ＰＺＮ－ＰＺ－ＰＴ固溶体弥散程度有所增加。     

钾离子掺杂PZN基陶瓷的相结构和介电性能

采用复相混合烧结制备出掺杂钾离子的PZN基陶瓷,研究了钾离子对PZN－BT－PT三元系弛豫铁电陶瓷的相结构、介电性能的影响。结果表明,钾离子掺杂可使材料的居里温度向低温方向移动,降低陶瓷的介电常数,但可有效改善陶瓷试样的温度稳定性;复相混合烧结可以消除由于钾离子掺杂而引起的焦绿石相;二者结合可获得具有纯钙钛矿相结构,弥散相变度宽（－100℃）,室温介电常数高,介电损耗低（0．011）的PZN基弛豫铁电陶瓷,并能显著提高材料的温度稳定性。     

A位取代对xPMnS-（1-x）PZN陶瓷相变特性的影响

研究了xPMnS-（1-x）PZN四元系压电陶瓷的相变特征，分析了Ba^2＋、Sr^2＋取代对材料相变特性的影响。结果表明，xPMnS-（1-x）PZN陶瓷具有弥散性相变特点，在相变过程中存在明显的介电热滞。Ba^2＋、Sr^2＋取代使相变温度降低，相变弥散性增强。Ba^2＋取代使介电热滞增加，Sr^2＋取代使介电热滞减小，这是由于Ba^2＋取代使非谐效应增强，利于顺电相的稳定，Sr^2＋取代使原胞间的相互作用增强，利于铁电相的稳定。     

掺杂对PMN-10PT铁电陶瓷介电性能的影响

铌镁酸铅与钛酸铅组成比为9:1(PMN-10PT)的固溶体陶瓷是典型的弛豫铁电体,其介电行为与偶极玻璃的介电行为极为相似.本文使用常用的Swartz两步法,研究了基体掺杂不同物质对PMN-10PT铁电陶瓷的介电性能的影响.经研究发现,当掺入Li₂O时,材料的峰值介电常数为28640,大于纯PMN-10PT,而频率色散和弥散相变的程度都变小.当掺杂CaO和Yb₂O₃时,材料的峰值介电常数下降,分别为19300和18850,它们的频率色散和弥散相变的程度都变大了.同时通过拉曼光谱研究了PMN-10PT陶瓷的B位离子有序度的变化.     

(K_(0.5)Na_(0.5))_(1-x)Li_xNb_(1-y)Sb_yO_3系无铅压电陶瓷的弥散相变研究

采用传统陶瓷工艺制备了(K0.5 Na0.5)1-xLixNb1-ySbyO3(KNLNSx-y,x=0～10%(摩尔分数),y=2%～8%(摩尔分数))系无铅压电陶瓷,研究了Li+和Sb5+的取代对KNLNSx-y系材料的相变弥散性的影响.结果表明,在所研究的组成范围内,KNLN-Sx-y,陶瓷都形成了单一的钙钛矿结构,Li+和Sb5+蚪进入了KNN晶格形成固溶体;随着Li含量的增加,KNLNSx-5陶瓷四方-立方相变的弥散性有所减弱;随着Sb含量的增加,KNLNS2-y,陶瓷四方-立方相变的弥散性有所增强.采用修正的居里-外斯定律能够较好的描述KNLNSx-y陶瓷在高于居里温度情况下的介电常数与温度的关系;利用有序-无序理论对该介电弥散现象进行了解释.     

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。     

PMN-BT陶瓷的介电性能和相变温度

制备了一系列PMN－BT陶瓷,系统地研究了BT含量的变化对介电性能和相变温度的影响。PMN－BT陶瓷的相变温度与组成吴“U”型变化曲线,相变温度的异常化是由于系统中存在Ba(Mg1/3Nb2/3)O3顺电微区所致。PMN－BT陶瓷的介电驰豫特性随BT的增加经历了一个由弱变强,再由强变弱的过程,对由两种钙钛矿化合物构成的铁电固溶体相变温度的变化规律进行了讨论。     

PMN-PT单晶与陶瓷在性能及相变方面的特点

着重介绍了用Ｂridgman方法生长的（１-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3(PMN-PT)固溶体单昌在介电,压电、热释电性能及相应方面的一些特点;①异常高的电常数d33(高达３０００pC/N以上）,耦合系数kg(在０．６以上）,k33(达０．９０）,高的介电常数ε（高达５００甚至更高）,低的Ｑm值（约６０）,热释电系数也较高。②强烈的各向异性。③随着ＰＴ含量的增加,系统的弛豫行为逐渐减弱,在x=0．３３时,材料在室温下成为正常铁电体,但ＰＥ－ＦＥ相变并非正常铁电相变,表现在Ｔ＞Ｔm时,ε－Ｔ关系不遵守居里－包斯定律,而是遵守Ｓmolenskii的关系。该相变也明显地与弥散相变不同,这种行为可用无场的观点加以解释。     

PZT的制备及其微观结构分析

PZT(Pb(ZrxTi(1-x)O3)是一种典型的三方-四方钙钛矿结构的铁电陶瓷，其微观结构对材料的铁电性能有很大的影响．我们用粉末烧结法制备PZT，对纯相PT(PbTiO3)和PZ(PbZrO3)的工艺进行研究．用X射线衍射仪对不同工艺条件制备的PZT，PT及PZ进行了结构分析．认为在使用Pb3O4作原料时并不需要文献[田长生，许建军，方晓华．烧结温度对0．85PZN-0．10BT-0．05PT陶瓷相结构的影响[J]．功能材料，1995，26(增刊)：358-359；杨祖陪，高峰，周欣山等．含铅弛豫铁电陶瓷的制备技术[J]．功能材料，1998，29(增刊)：533-535]所报道的需使反应处于富铅状态；计算分析还表明通过配比控制，可以使PZT的四方度符合使用要求．分析PZT中三方-四方相的共存与转变，认为其与内应力有关．     

Ti~(4+)对PbZrO_3和Pb(Zr_(1-x)Ti_x)O_3粉体晶格结构的影响

研究了Ti4+离子对PbZrO3和Pb(Zr1-xTix)O3粉体晶格结构的影响。利用固相反应法合成的PbZrO3和Pb(Zr0.95Ti0.05)O3粉体,从XRD、晶格常数和Raman光谱3个方面进行了分析。结果表明:PbZrO3和Pb(Zr0.95Ti0.05)O3均为钙钛矿结构,但较之PbZrO3,Pb(Zr0.95Ti0.05)O3的XRD谱各个峰位均向高角度轻微偏移;晶胞参数变小;Pb(Zr0.95Ti0.05)O3的Raman峰除在低频区向低频方向发生了偏移,而其余峰均向高频方向发生了偏移且部分峰有宽化现象。主要是由于Ti4+离子部分取代Zr4+离子进入PbZrO3晶格而形成Pb(Zr1-xTix)结构。     

Structure and electrical properties of (111)-oriented Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3 thin film for ultra-high-frequency transducer applications

Ternary lead magnesium niobate-lead zirconate titanate system 0.4Pb(Mg(1/3)Nb(2/3))O(3)-0.25PbZrO(3)-0.35PbTiO(3) (40PMN-25PZ-35PT) thin film with a thickness of 1.5 μm was grown on Pt(111)/Ti/SiO(2)/Si substrate via chemical solution deposition. X-ray diffraction and transmission electron microscopy results suggested the film obtained was highly (111)-oriented. The remanent polarization and coercive electric field of the film were found to be 25.5 μC/cm(2) and 51 kV/cm, respectively. In addition, at 1 kHz, the dielectric constant was measured to be 1960 and the dielectric loss 0.036. The film was observed to undergo a diffuse ferroelectric-to-paraelectric phase transition at around 209°C. The leakage current appeared to depend on the voltage polarity. If the Au electrode was biased positively, the leakage current was dominated by the Schottky emission mechanism. When the Pt electrode was biased positively, the conduction current curve showed an ohmic behavior at a low electric field and space-charge-limited current characteristics at a high electric field.     

Dielectric and ferroelectric properties of Bi(Zn1/2Ti1/2)O3-PbTiO3-PbZrO3 ternary ceramics

Ceramics of a new ternary solid solution system, xBi(Zn(1/2)Ti(1/2))O(3-yPbTiO(3)z)PbZrO(3) (xBZT-yPT-zPZ), with compositions along the solubility limit curve are prepared by solid-state reaction and sintering technique. Two morphotropic phase boundaries (MPBs) separating the orthorhombic and tetragonal (MPB(O-T)) phases and the tetragonal and rhombohedral (MPB(T-R)) phases, respectively, are observed with increasing z (0.10 ≤ x ≤ 0.21; 0 ≤ y ≤ 0.49). It is found that the transition from the ferroelectric to paraelectric phase becomes more diffuse with the addition of BZT into the PZT solid solution. Enhanced dielectric and ferroelectric properties appear at MPB(R-T), which exists over a wide composition region (0.45 ≤ z ≤ 0.6), as revealed by X-ray diffraction and dielectric measurements. The dielectric constant reaches a maximum value (ε' = 1250) on the tetragonal majority side of the MPB. The highest remnant polarization (P(r) = 34.2 μC/cm(2)) is found in the composition at the center of the MPB, where the rhombohedral and tetragonal phases coexist in almost equal quantities.     

Lead recovery from PbZrO3 using wet ball-mill technique and hydrothermal synthesis of alpha-zirconium phosphate from wastewater for resource recovery

Lead recovery from lead zirconate (PbZrO(3)) ceramics was investigated using a wet ball-mill treatment in H(2)SO(4) aqueous solution. Subsequently crystalline alpha-zirconium phosphate (alpha-Zr(HPO(4))(2).H(2)O) was synthesized using a hydrothermal technique in order for the resource recovery of zirconium in the wastewater after the wet ball-mill treatment. A wet ball-mill treatment in 4.5M H(2)SO(4) aqueous solution for 24h was capable of converting more than 99.9% of the Pb initially included in the PbZrO(3) to solid state PbSO(4) with a purity of 98%. On the other hand, the Zr in the PbZrO(3) was dissolved into the acidic solution during the treatment. The Pb and Zr metal elements coexisting in PbZrO(3) were successfully separated by the wet ball-mill technique. Then, resource recovery of zirconium in the wastewater was examined. Crystalline alpha-Zr(HPO(4))(2).H(2)O was synthesized by hydrothermal treatments in 3.1-12.5M H(3)PO(4) aqueous solutions at temperatures of 120-240 degrees C for a duration of 70h. The hydrothermally prepared powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and then they were also evaluated in terms of cation exchange capacity (CEC) measurement and thermogravimetric (TG) analysis.     

纳米钛酸钡陶瓷的特殊烧结方法和新颖特性的研究进展

对近年来有关纳米钛酸钡陶瓷最新的烧结方法、新颖性质进行了综合评述和讨论。当晶粒尺寸减小到纳米尺度时，钛酸钡陶瓷的晶体结构在不同的温度下出现了不同的多相共存。这可以用纳米钛酸钡陶瓷相变产生的应力来解释。纳米钛酸钡陶瓷的铁电性能表现出新颖的特性。它的介电常数先随晶粒尺寸的减小而降低，但当晶粒尺寸降低到小于50nm甚至小于10m时，介电常数表现出反常的增加，同时铁电向顺电的转变峰变为一个很宽的峰，表现出弥散相变的特征。     

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．     

Biferroic LuCrO3: Structural characterization,magnetic and dielectric properties

Multiferroic LuCrO₃ perovskite-type structure (Pbnm) obtained via auto-ignition synthesis was characterized by a combination of X-ray diffraction (XRD) and thermogravimetric (TG) techniques, and through magnetization and permittivity measurements. Results showed that amorphous combustion powders were fully transformed to orthorhombic LuCrO₃ structure at 1200 K after the first LuCrO₄ crystallization at 700 K. The magnetic response displays thermal irreversibility between zero-field-cooling and field-cooling condition which is due to spin canted AF switching at 116 K. Accordingly, a hysteresis loop in the M(H) data confirms weak ferromagnetism in LuCrO₃. On the other hand, the permittivity measurement shows a broad peak transition typical of relaxor-type ferroelectrics transition at ∼450 K. Electrical conductivity increases as temperature increases showing an anomaly around the diffuse phase transition. The diffuse phase transition and the formation of the charge carriers are discussed in terms of a local distortion around the Lu Site.     

Evolution of weak ferroelectricity dielectric response in PbZrO3 antiferroelectric thin films

Journal of Materials Science: Materials in Electronics - In this study, the ferroelectric domain wall contributions to the permittivity is investigated in a PbZrO3 antiferroelectric thin film far...