掺杂对0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3陶瓷结构和电学性能的影响

用传统的固相反应法、通过铌铁矿预合成路线制备了1mol%ZnO、MnO2和CuO掺杂的0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3(0.7PMN-0.3PT)陶瓷。XRD分析表明掺杂的0.7PMN-0.3PT陶瓷都呈现纯三方钙钛矿结构。烧成的陶瓷具有较高的致密度,其中CuO掺杂的0.7PMN-0.3PT陶瓷达到理论密度的93.79%。掺杂的0.7PMN-0.3PT陶瓷都呈现宽化、弥散的介电响应峰,然而介电常数的频率色散现象明显减弱。CuO掺杂的0.7PMN-0.3PT陶瓷呈现优良的综合电学性能:介电常数最大值εm达到21000左右,剩余极化强度Pr达到27.49μC/cm2,压电应变常量d33达到548pC/N。     

La2O3掺杂（Na0．5 Bi0．5）0．94 Ba0.06 TiO3无铅压电陶瓷的介电弛豫研究

采用固相合成法制备了La2O3掺杂(Na0.5Bi0.5)0.94Ba0.06TiO3无铅压电陶瓷.研究了La2O3掺杂对(Na1/2Bi1/2)TiO3陶瓷晶体结构、介电性能与介电弛豫行为的影响.XRD分析表明,在所研究的组成范围内陶瓷材料均能够形成纯钙钛矿固溶体.材料的介电常数-温度曲线显示陶瓷具有两个介电反常峰Tf和Tm.修正的居里-维斯公式较好的描述了陶瓷弥散相变特征,弥散指数随La2O3掺杂量的增加而增加.掺杂量较低的陶瓷仅在低温介电反常峰Tf附近表现出明显的频率依赖性,随掺杂量的增加,陶瓷材料在室温和低温介电反常峰Tf之间都表现出明显的频率依赖性.并根据宏畴-微畴转变理论探讨了该体系陶瓷介电弛豫特性的机理.     

BaNb2O6掺杂Na1/2Bi1/2TiO3无铅压电陶瓷的介电弛豫

采用传统陶瓷制备方法,制备了无铅新压电陶瓷材料Na1/2Bi1/2TiO3-xBaNb2O6.研究了BaNb2O6掺杂对(Na1/2Bi1/2)TiO3陶瓷晶体结构、介电性能与介电弛豫行为的影响.XRD分析表明,在所研究的组成范围内陶瓷材料均能够形成纯钙钛矿固溶体.材料的介电常数-温度曲线显示陶瓷具有两个介电反常峰Tf和Tm,修正的居里一外斯公式较好的描述了陶瓷弥散相变特征,弥散指数随BaNb2O6掺杂量的增加而增加.该体系陶瓷表现出与典型弛豫铁电体明显不同的弛豫行为,低掺杂量的陶瓷仅在低温介电反常峰Tf附近表现出明显的频率依赖性,而高掺杂的陶瓷材料在室温和Tf之间都表现出明显的频率依赖性.并根据宏畴一微畴转变理论探讨了该体系陶瓷产生介电弛豫的机理.     

铅掺杂对BST铁电薄膜性能的影响

为了改善BST铁电薄膜的结晶性能,降低薄膜材料的铁电弛豫和弥散相变特性,采用改进的溶胶-凝胶(sol-gel)方法在Pt/Ti/SiO2/Si基片上制备出了不同铅掺杂的BST薄膜(PBST).研究了PBST薄膜的微观结构及其介电、铁电性能.XRD、AFM分析表明,铅对(101、110)峰的生长促进作用最大,掺入5mol%Pb以上的PBST薄膜的结晶状况得到了明显改善;铅的引入使晶粒增大,降低了薄膜的频率色散现象,相变温区有不同程度紧缩;薄膜的介电、铁电性增强.PBST(0.80/0.20/0.05)薄膜具有适当的相变温区、合适的Tmax值、较小频率色散及比BST薄膜更为明显的介电峰与铁电性等特征,可以作为UFPA系统的探测材料.     

掺杂对PMN铁电陶瓷烧结工艺和介电性能的影响

使用常用的两步法,研究了基体掺杂不同物质对ＰＭＮ陶瓷的烧结工艺和介电性能的影响．经研究发现,当掺杂 １ｍｏｌ％Ｌｉ_２Ｏ时,可以实现 ９５０～１０００℃左右的中温烧结,材料的常温介电常数和介电损耗分别为 １３５００和 ０．５５％,都优于纯 ＰＭＮ．当掺杂 ２ｍｏｌ％时,可以将烧结温度降到８００～９００℃的低温烧结范围,且介电损耗明显下降．分析结果表明;材料的显微结构良好,材料的致密化程度较高．另外,掺加 Ｌｉ_２Ｏ和 ＳｒＯ可以分别稍微减小和增加材料的弥散相变程度．同时本文还研究了ＰＭＮ陶瓷的微观结构和介电弛豫的情况．     

细晶Ba0.6Sr0.4TiO3(BST)陶瓷材料的制备与介电性能

采用改进的Sol-gel工艺和传统烧结技术制备了晶粒尺寸在0.15～10μm的Ba0.6Sr0.4TiO3(BST)陶瓷,观察了样品的显微结构,并对样品的介电性能进行了测试,分析了晶粒尺寸对材料介电性能的影响.实验结果表明:改进的Sol-gel工艺和两步烧结法可以有效地控制Ba0.6Sr0.4TiO3(BST)陶瓷的晶粒尺寸.晶粒尺寸的降低,材料的介电常数也随之下降,介电峰呈现明显的铁电-顺电弥散相变;但当陶瓷的晶粒尺寸＜1 μm,介电常数出现峰值,铁电相变温区变窄.     

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。     

PZT95/5铁电陶瓷的掺杂改性研究

采用固相烧结法制备锆钛酸铅95/5(PZT95/5)材料,以“相同化合价,不同原子半径;相近原子半径,不同化合价”的原则,选择了碱金属族、碱土金属族元素的碳酸盐以及Fe₂O₃、SiO₂、Nb₂O₅、WO₃等作为掺杂物分别对其进行掺杂改性.研究了掺杂对材料介电性能、极化性能和低温-高温铁电相的相变温度的影响.发现受主掺杂使得材料的介电常数降低,施主掺杂使得材料的介电常数提高;剩余极化随着掺杂离子的化合价增大而增大;制备得到了低温-高温铁电相相变在15℃的铁电材料,在实际应用上有重要意义.     

氧化锆掺杂BaTiO_3陶瓷显微结构和介电性能研究

为了改变纯钛酸钡陶瓷的介电性能,以钛酸钡和氧化锆为原料,通过固相烧结法制备了不同物质的量比氧化锆掺杂钛酸钡基介电陶瓷。利用X射线衍射仪、透反射偏光显微镜和安捷伦LCR仪分析了其显微组成、相结构和介电特性。实验表明:氧化锆的掺杂不改变钛酸钡的晶体结构,当频率保持不变时,改变氧化锆在BaTiO3陶瓷中的掺杂量不会影响介电峰的位置,只影响了峰值大小。当掺杂物质的量比保持不变时,改变频率对峰的位置影响较大,呈现出随着频率的增加向高温区移动,峰值由大到小再到大的现象。在100 Hz下,当掺杂物质的量比为1.08∶100时介电常数最大。     

驰豫型铁电体的宏观介电性能与极化机制研究

驰豫型铁电体是很重要的功能材料,其介电性能和极化机制一直是研究的热点。作者通过对掺钛铌镁酸铅系列铁电陶瓷介电、铁电、热电等宏观性能和微观结构详细、系统的实验研究,提出铁电微畴为三方相畸变结构散布于立方钙钛矿母相中,通过类马氏体预相变的位移型形核过程,实现顺电—驰豫型铁电态的弥散相变,进一步通过类马氏体相变,完成驰豫型铁电态无序态分布的微畴向正常铁电态长程序铁电宏畴转变;提出T_1可调整A(B′B″)O_3型复合钙钛矿铁电体B′和B″离子价态和离子半径等不同所产生的内电场和弹性场,使立方母相所承受切应力发生变化,诱发极性微区、铁电微畴随组成变化表现不同活性。对弛豫型铁电体介电谱分析与计算表明,其在介电常数峰值温度Tm附近的介电弛豫过程连续变化,不对应结构突变的相变过程,较接近偶极介质。通过铌锌酸铅基系列铁电陶瓷在准同型相界附近异常特性的研究,进一步揭示弛豫型铁电体中结构特征决定宏观行为的必要性,反映出铁电材料由微观到介观、再到宏观的有趣规律性。在此基础上,对复合钙钛矿弛豫型铁电体偏压介电行为、电致伸缩特性、介电老化行为等进行了系统研究,合理解释了一系列新的实验现象和结果;并对钨青铜结构铌酸锶钡弛豫型铁电陶瓷复介电响应进行了详细的对比分析和讨     

Effects of fine metal oxide particle dopant on the acoustic properties of silicone rubber lens for medical array probe

The effects of fine metal oxide particles, particularly those of high-density elements (7.7 to 9.7 x 10(3) kg/m3), on the acoustic properties of silicone rubber have been investigated in order to develop an acoustic lens with a low acoustic attenuation. Silicone rubber doped with Yb2O3 powder having nanoparticle size of 16 nm showed a lower acoustic attenuation than silicone rubber doped with powders of CeO2, Bi2O3, Lu2O3 and HfO2. The silicone rubber doped with Yb2O3 powder showed a sound speed of 0.88 km/s, an acoustic impedance of 1.35 x 10(6) kg/m2s, an acoustic attenuation of 0.93 dB/mmMHz, and a Shore A hardness of 55 at 37 degrees C. Although typical silicone rubber doped with SiO2 (2.6 x 10(3) kg/m3) shows a sound speed of about 1.00 km/s, heavy metal oxide particles decreased the sound velocities to lower than 0.93 km/s. Therefore, an acoustic lens of silicone rubber doped with Yb2O3 powder provides increased sensitivity because it realizes a thinner acoustic lens than is conventionally used due to its low sound speed. Moreover, it has an advantage in that a focus point is not changed when the acoustic lens is pressed to a human body due to its reasonable hardness.     

Emission Properties of Yb3+/Er3+ Doped TeO2-WO3-ZnO Glasses for Broadband Optical Amplifiers

The YbS /Er3 doped TeO2-WO3-ZnO glasses were prepared. The absorption spectra, emission spectra and fluorescence lifetime of Era at 1.5μm, excited by 970 nm were measured. The influence of Er2Oa, Yb2Oa and Ohcontents on emission properties of Era at 1.5 μm was investigated. The optimum doping concentrations for Era and Yba is around 3.34× 1020 ions/cma and 6.63×1020 ions/cma, respectively. The peak emission cross section is 0.83～0.87 pm2. With the increasing concentration of Yba , the FWHM of Era emission at 1.5 μm in the glass increases from 77 nm to 83 nm. The results show that Yba /Era doped meO2-Woa-ZnO glasses are promising candidate for Era -doped broadband optical amplifier.     

Extended X-ray absorption fine structure (EXAFS) study of secondary phases in Yb2O3-doped Si3N4 ceramics

Liquid-phase sintered Si3N4 doped with Yb2O3 as a sintering aid was characterized by both transmission electron microscopy and extended X-ray absorption fine structure (EXAFS) measurements. Structural information about the secondary phases was obtained with an emphasis being placed on the evaluation of EXAFS data. Two Si3N4 samples were processed which contained either 5 vol% or 10 vol% Yb2O3 as sintering additive. After sintering, only an amorphous secondary phase was observed in the material doped with 5 vol% Yb2O3. The material with the higher Yb2O3 volume fraction underwent a further heat treatment after the densification, in order to crystallize pockets of the secondary phase. This heat treatment resulted in the formation of Yb2Si2O7 at multi-grain junctions, with however, amorphous phases remaining along the grain and phase boundaries. The EXAFS data obtained from the two doped Si3N4 materials were compared with reference spectra obtained on pure Yb2O3 and synthetic Yb2Si2O7. No residual Yb2O3 was determined in the doped Si3N4 materials, independent of the Yb2O3 volume fraction. Compared to synthetic Yb2Si2O7, the secondary phase formed in the 10 vol% Yb2O3 containing material showed only subtle changes in the EXAFS data. A clear distinction between purely amorphous and a combination of crystalline plus amorphous Yb secondary phases was possible, when both doped Si3N4 materials were compared. However, no distinction between the glass phase present at triple junctions and the amorphous residue along grain/phase boundaries was feasible, since a full numerical data evaluation could not be performed.     

Effect of dopants on ageing properties for the PMN-0.1 PT relaxor ferroelectric ceramics

Isothermal ageing properties of the typical ferroelectric relaxor system Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (abbreviated as PMN-0.1 PT) doped with different kinds of oxides were measured and the effect of dopants on ageing inducing was investigated. The metallic ions of additives were considered to enter sites A or B in the perovskite structure with similar radii and their roles were distinguished as donors, acceptors or equivalent substitutors due to their valences. For the additions of acceptors, dielectric ageing is evident while no obvious ageing was found in the non-doped equivalently substituted or donor-doped PMN-0.1 PT systems.     

P2O3-B2O3-Al2O3-SrO-BaO玻璃中Yb3+非辐射能量转移下Er3+离子的增强发射

本文研究了共掺Er3 +/Yb3 +P2 O3 -B2 O3 -Al2 O3 -SrO -BaO玻璃的能量转移过程。实验中制备了高掺杂Yb3 +离子的双掺Er3 +/Yb3 +的磷酸盐玻璃样品。在Er3 +/Yb3 +掺杂比率 >1 :1 8(mol% )时 ,观测到了基于Yb3 +离子至Er3 +离子能量转移下Er3 +( 4 I13 / 2 →4I15 / 2 )的增强发射和Yb3 +( 2 F7/ 2 →2 F5 / 2 )发射的减弱 ,当Yb3 +离子掺杂浓度超过 2 .1× 1 0 2 1ions/cm3 时 (Er3 +/Yb3 +≤ 1 :1 8,mol% ) ,由于Yb3 +离子的自淬灭效应 ,Er3 +离子的发射强度降低。实验中得到了Yb3 +离子的最佳掺杂浓度为1 .74× 1 0 2 1ions/cm3     

铒单掺和铒/镱共掺氟氧玻璃的上转换发光性质研究

研究了室温下掺不同摩尔分数Er3+单掺和Er3+/Yb3+双掺的20GaF3-15InF3-17CdF2-15ZnF2-10SnF2-3P2O5-(20-x-y)PbF2-xErF3-yYbF3(x=0.1~0.4,y=1~4)氟氧玻璃的上转换发光性质。755nm激发下,在Er3+单掺系列玻璃中观察到紫色(410nm)、蓝色(465nm)和绿色(522nm、544nm)上转化发光,随着掺杂Er3+浓度的增大,各荧光强度增幅有变缓的趋势。980nm激发下,由于Yb3+的敏化作用,在Er3+/Yb3+双掺系列玻璃中观察到绿色(548nm、527nm)和红色(661nm)上转换发光,固定Er3+浓度,随着Yb3+浓度的增大,各荧光强度先增大后减小,当Yb3+、Er3+掺杂浓度比为15时发光强度最大。该氟氧玻璃具有比氟化物玻璃更好的抗析晶稳定性,掺稀土离子后在不同波长激发下可观察到明亮的红、绿色上转换荧光,是一种有潜质用于红、绿色上转换发光的材料。     

High-performance PMN-PT thick films

This article describes some of our work on ?.??Pb(Mg?/?Nb(?/?)O?-?.??PbTiO? (0.65PMN-0.35PT) thick films printed on alumina substrates. These thick films, with the nominal composition ?.??Pb(Mg?/?Nb(?/?)O?-?.??PbTiO?, were produced by screen-printing and firing a paste prepared from an organic vehicle and pre-reacted fine particles of avery chemically homogeneous powder. To improve the adhesion of the 0.65PMN-0.35PT to the platinized alumina substrate,a Pb(Zr?.??Ti?.??)O? layer was deposited between the electrode and the substrate. The samples were then sintered at 950 °C for 2 h with various amounts of packing powder on the alumina (Al?O?) substrates. The sintering procedure was optimized to obtain dense 0.65PMN-0.35PT films. The films were then characterized using scanning electron microscopy as well as measurements of the dielectric and piezoelectric constants.The electrostrictive behavior of the 0.65PMN-0.35PT thick films was investigated using an atomic force microscope(AFM). Finally, substrate-free, large-displacement bending type actuators were prepared and characterized, and the normalized displacement (i.e., the displacement per unit length) of the actuators was determined to be 55 μm/cm at 3.6 kV/cm.     

纳米(ZnO,Al2O3)复合掺杂对3Y2O3-ZrO2材料电性能的影响

以3Y2O3—ZrO2纳米粉和ZnO，A12O3纳米粉为原料，采用交流阻抗谱技术对掺少量ZnO和A12O3的3Y2O3—ZrO2烧结陶瓷进行电性能研究。研究表明：少量纳米ZnO掺杂降低了3Y2O3—ZrO2的电导率，但随着掺人量的增加，电导率开始回升。在ZnO掺杂样品中加入少量纳米A12O3进行复合第二相掺杂，结果提高了3Y2O3—ZrO2材料的电导率。同时少量A12O3的掺人降低了晶粒电导活化能，使得晶粒电导率增加。     

Li2CO3-B2O3-V2O5掺杂ZnO-TiO2陶瓷低温烧结的研究

以Li2CO3、B2O3和V2O53种常见的低熔点氧化物为烧结助剂,用传统固相法制备了Li2CO3-B2O3-V2O5掺杂的ZnO-TiO2微波介质陶瓷,并利用XRD、SEM等研究了ZnO-TiO2陶瓷的烧结行为、物相组成、显微结构特征及微波介电性能等。结果表明,当掺入3%(质量分数)Li2CO3-B2O3-V2O5时,在840℃烧结2h可制备出体积密度为4.99g/cm3的ZnO-TiO2陶瓷,达到理论密度的96.5%以上,εr、Q.f、τf分别约为24、22900GHz、-4×10-6/℃。