Electrorheological Particles Composed of Polyaniline Core and BaTiO_3 Layer Shell

Composite particles consisting of polyaniline( PAn) core and barium tilanate ( BaTiO3) Layer shell were synthesized. The PAn-BaTiO3 composites particles were characterized with TEM and XRD. The dielectric behavior of particles was tested and the electrorhcologicak(ER) behavior of the suspensions of PAn/ BaTiO3 panicles in chlorinated paraffin oil with a 20vol % was investigated under DC electric field. The results show that the ER effect of composite particle is far stronger than that of pure polyaniline and barium titanate which mere synthesized by the stone method. pH and thickness of BuTiO3 have an important. influence on the ER effects.     

Electrorheological Properties of Suspensions of PAn-PEO-PAn Triblock Copolymer Particles

The PAn-PEO-PAn triblock copolymer with the PEG chain length of 400 was synthesized by chemical oxidation copolymerization of aniline and α,ω-bis（p-aminophenyl）poly（ethylene glycol）and characterized by FT-IR and TEM.The experimental results show that the copolymer particles are of μtypical core-shell structure after the self-assembly process in water.Its conductivity is much lower than that of the pure PAn.The suspension containing 20 vol% PAn-PEO-PAn tiblock copolymer in silicone oil exhibits.a typical electrorheological （ER） effect in DC electric field.while it shows a lower leakage current density than that of the pure PAn-based ER fluids.Therefore,the PEO shell hinders the electric hop among PANI chains and decreases the current density of ER fluids in an external electric field.at the same time the interface polarity improves the ER effects.     

A Novel Process for Synthesis of Ultrafine BaTiO3 Powders

A novel process termed low-temperature combustion-synthesis(LCS)of Ba(ON3)2-TiO2-C6H8O7.H2O system was investigated at the initial temperature of 600℃ and ultrafine BiTiO3 powders with a particle size of 200-350nm were prepared.It was found that the molar ratio of NO3^-/citric acid and the homogeneity of combustion have remarkable effect on the characterstice of the powder,The reaction mechanism of LCS BaTiO3 powders was proposed on the basis of thermodynamic analysis.     

Effect of milling process on the core-shell structures and dielectric properties of fine-grained BaTiO3-based X7R ceramic materials

Fine-grained BaTiO3-based X7R ceramic materials were prepared and the effects of milling process on the core-shell structures and dielectric properties were investigated using scanning electron microscope, transmission electron microscope, and energy dispersive spectroscopy (EDS). As the milling time extends, the dielectric constant of the ceramics increases, whereas the temperature coefficient of capacitance at 125°C drops quickly. The changes in dielectric properties are considered relevant to the micro-s...     

Preparation and densification of BaTiO3 nanopowder by sol—gel autoigniting synthesis

Autoigniting synthesis of gel from Ba(NO3)2,TiO(NO3)2 and C6H8O7.H2O aqueous solution was investigated at an initial temperature of 600℃ and tetragonal BaTiO3 nanopowder with particle size of 80nm was prepared.It is indicated that the specific surface area of the combustion product before and after calcination is 14.74m^2/g and 12.49m^2/g,respectively.The combustion wave is composed of solid phase reaction zone and gaseous phase flame reaction zone.The combustion flame temperature is 1123K derived from thermo couple measurement.The characteristics and densification behavior of the sol-gel autoigniting synthesized BaTiO3 nanopowder were in vestigated.     

钛酸钡分子核磁共振的量子化学研究

用量子化学从头计算方法，在RHF／LANL2DZ的水平上对单个BaTiO3分子进行了基态构型优化。在此基础上进行了两种规范变换方法（GIAO和CSGT）的RHF／LANL2DZ的NMR屏蔽张量计算，得到与BaTiO3jjj wsg NMR实验研究相符合的结果。     

The Synthesis and Electrorheological Properties of BaTiO_3-coated PMMA Microspheres

Coated-PMMA microspheres consisting of poly (methyl methacrylate)(PMMA) core and barium titanate (BaTiO3) shell were synthesized by the modified sol-gel processing and then adopted as an electrorheological (ER) materials. The structure and morphology of coated powders were characterized by SEM and FT-IR; the shear stress of the suspensions of coated-PMMA particles and pure PMMA particles in silicone oil with a 20 vol% were investigated. The results show that the BaTiO3 coated PMMA microspheres based suspension in silicone oil exhibited typical ER behavior and stronger ER effects.     

钛酸钡薄膜的喷雾热分解方法制备及PTC效应研究

介绍了在Pt／Ti/Si(100)衬底上用溶胶溶液和喷雾热分解方法制备BaTiO3薄膜，并研究其PTC效应。富钛3％的钛酸钡溶胶溶液在衬底温度650℃环境下成膜，氧气作为载气其流量为1．5L／min，800℃环境下退火2h。在大于居里点温度Tc(138℃)时表现出良好的PTC效应。钛酸钡薄膜厚度1500nm时，室温下极间电阻为70Ω。在大于居里点温度Tc(138℃)时，极间电阻可达10^6Ω。     

镨对锰掺杂钛酸钡陶瓷结构和介电性能的影响

采用冷压陶瓷技术制备了锰掺杂及镨锰共掺杂钛酸钡陶瓷.1.0%锰在钛酸钡中的掺杂导致形成四方和六方钙钛矿混合结构;镨的进一步掺杂导致六方相消失,形成四方钙钛矿单相结构.同时研究了镨对锰掺杂钛酸钡陶瓷介电性能的影响.     

Sr/Zr掺杂以及抛光对BaTiO_3陶瓷结构和介电性能的影响

采用冷压陶瓷技术制备了(Ba0.75Sr0.25)TiO3、Ba(Ti0.8Zr0.2)O3、(Ba0.75Sr0.25)(Ti0.8Zr0.2)O3陶瓷.XRD结果表明,Sr和Zr在BaTiO3的Ba位、Ti位、及Ba/Ti双位并入均具有高固溶性,且为没有超结构特征的单相钙钛矿结构.Sr/Zr的双位并入加快介电峰向低温的移动.Sr掺杂对Ba(Ti0.8Zr0.2)O3介电峰移动率的贡献为-1.5℃/mol%Sr.抛光技术对介电温谱的影响研究表明,尽管水抛光导致(Ba0.75Sr0.25)(Ti0.8Zr0.2)O3陶瓷颜色变暗,但晶体结构不变、介电峰值降低.     

Effect of SiO2 addition on the dielectric properties and microstructure of BaTiO3-based ceramics in reducing sintering

The effect of SiO2 doping on the sintering behavior,microstructure,and dielectric properties of BaTiO3-based ceramics has been investigated.Silica was added to the BaTiO3-based powder prepared by the solid state method with 0.075mo1%,0.15mo1%,and 0.3mo1%,respectively.The SiO2-doped BaTiO3-based ceramic with high density and uniform grain size were obtained,which were sintered in reducing atmosphere.A scanning electron microscope,X-ray diffraction,and LCR meter were used to determine the microstructure as well as the dielectric properties.SiO2 can form a liquid phase belonging to the ternary system of BaO-TiO2-SiO2,leading to the formation of BaTiO3 ceramics with high density at a lower sintering temperature.The SiO2-doped BaTiO3-based ce-ramics can be sintered to a theoretical density higher than 95% at 1220℃ with a soaking time of 2 h.The dielectric constants of the sample with 0.15mo1% SiO2 addition sintered at 1220℃ is about 9000.Doping with a small amount of silica can improve the sinter-ing and dielectric properties of BaTiO3-based ceramics.     

片状钛酸钡颗粒的熔盐法制备及其形貌

为了得到有利于晶粒择优取向的片状钛酸钡形貌颗粒,采用合成出的片状模板原料,通过熔盐法制备了片状钛酸钡颗粒.首先,以碳酸钾、二氧化钛和钛酸锂为原料,在氯化钾熔盐中制备了具有类纤铁矿层状结构的钛酸盐（K0.8Ti1.73Li0.27O4）.经酸交换后,得到了片状钛酸（H1.07Ti1.73O4,HTO）颗粒.HTO是一种具有层间通道结构和良好的离子交换性的片状模板,以HTO和碳酸钡为原料,氯化钠和氯化钾为熔盐,在820℃保温5h得到纯相的钛酸钡,其颗粒形貌呈现为宽5～8μm、长10～15μm,厚度约1μm左右的片状形貌,而且这些片状颗粒是由1μm的小片状颗粒按特定晶向排列而成.结果表明以HTO为模板的原位反应机制起了主要作用,产生保持了片状HTO模板形状的片状钛酸钡颗粒.该方法有望为制备织构化陶瓷提供良好各向异性钛酸钡粉体.     

溶胶-凝胶法制备BaTiO3纳米粉体

阐述了用溶胶－凝胶工艺的半醇盐法制备BaTiO3纳米粉体的基本原理和工艺流程，讨论了溶剂、pH值、Ti/Ba摩尔比以及热处理工艺对BaTiO3纳米粉体性能的影响，并分析了目前以该法制备BaTiO3纳米粉体存在的问题。     

微波合成SiO2气凝胶核/聚苯乙烯壳微球研究

将水玻璃为硅源所制备的纳米孔硅气凝胶与苯乙烯单体用微波加热合成法制备出SiO2气凝胶核/聚苯乙烯壳复合微球.用顺序间隔取样测试方法试验复合微球的密度、转化率和包覆率与微波合成温度、时间和聚合体系各组分变化情况,分析讨论了影响变化因素和原因.通过TEM和FE-SEM对复合微球进行结构与形貌表征.结果表明,优选体系组分配比为SiO2气凝胶3g、苯乙烯21g、乙醇水溶剂配比为380g∶20g、引发剂4.2g及稳定剂2g,微波合成工艺参数为加热功率500W,加热时间40min、加热温度60℃.在此工艺条件下合成,复合微球合成转化率是67.1%、包覆率为32.7%,制备出的核壳结构复合微球的粒径约为100~200nm、震实密度为0.353g/cm3,且表面凹凸不平状似"草莓"的微粒.     

(Ba,Eu)TiO_3细晶粒陶瓷制备中的影响因素

采用冷压陶瓷技术,分别在1 400℃和1 300℃制备了具有四方结构的(Ba_(1-x)Eu_x)TiO_3和(Ba_(1-x)Eu_x)Ti_(1-x/8)O_3陶瓷.应用X射线衍射(XRD)、扫描电子显微镜(SEM)和原子力显微镜(AFM)研究Eu含量、Ti空位缺陷和陶瓷化烧结温度的变化对制备(Ba,Eu)TiO_3细晶粒陶瓷的影响因素.结果表明:当x=0.05时,1 300℃制备的(Ba_(1-x)Eu_x)Ti_(1-x/8)O_3陶瓷细化到平均晶粒尺寸小于1μm,1 400℃制备的(Ba_(1-x)Eu_x)TiO_3陶瓷却畸变生长到5μm.而x=0.03时,(Ba_(1-x)Eu_x)TiO_3陶瓷仍能细化到1μm.说明较高的陶瓷化烧结温度并不是晶粒生长的主要原因,Ti空位的存在起到抑制晶粒生长的作用.x≥0.07时,(Ba_(1-x)Eu_x)TiO_3陶瓷为大于5μm的粗晶粒陶瓷,说明Eu含量的继续增加不能抑制晶粒生长.     

KIO3掺杂聚苯胺电极材料的制备与性能

采用化学法并通过KlO3和盐酸与苯胺复合掺杂合成掺杂态聚苯胺。用红外光谱和扫描电镜对掺杂态聚苯胺进行了结构形态分析。将掺杂态的聚苯胺混合20％的石墨粉体，制成聚合物复合电极，以锌为负极组成电池，在恒电流条件下进行充放电性能的测试，结果表明，电极开路电位达1．8V，以20mA／cm^2恒电流充电，2mA／cm^2恒电流放电，放电工作平台为1．4V，设定终止电压为1．1V时，可持续放电13h，电池容量较大，结构稳定。     

溶胶低温燃烧法制备Ba0.7Sr0.3TiO3纳米粉体

以Ba(NO3)2Sr(NO3)2TiO(NO3)2C6H8O7.H2O为反应体系,采用溶胶低温燃烧合成法制备了Ba0.7Sr0.3TiO3超细粉末。以正交试验考察了柠檬酸与金属离子物质的量比、溶胶pH值、燃烧及热处理温度对合成粉体粒径的影响,得到的工艺参数最优组合为:n(柠檬酸)∶n(金属离子)=1.5∶1,pH=7,燃烧及热处理温度为650℃。对比了溶胶燃烧法与凝胶燃烧法对BST粉末粒度和相结构的影响。应用X射线衍射和透射电镜等对粉体的相结构、粒径、形貌进行了分析和观察。     

Dielectric and Piezoelectric Properties of 0-3 PZT/PVDF Composite Doped with Polyaniline

Lead zirconate titanate （ PZT ） / polyvinylidene fluoride （PVDF） 0-3 piezoelectric composites doped with polyaniline （PANI） were obtained by hot-press method. The polarization properties of the composites were characterized by XRD and P- E hysteresis loops at room temperature. And the dielectric and piezoelectric properties were also measured. The results show that the poling of PZT could be effectively carried oat and the dielectric constant e, and dissipation tanδ increase monatonously by increasing the volume fraction of PANI in the composite. The piezoelectric constant d33, and the planar electromechanical coupling factor kp increase while the mechanical quality factor Qm decreases with the increase in the content of PANI. The d33, kp and Qm show the extremum values at 8 vol%-10 vol% PANI.     

Impedance Spectroscopy of Ion Beam Mixed Cu/BaTiO_3PTCR Ceramics

The positive temperature coefficient resistance ( PTCR) barium titanate ceramic samples have been prepared by the standard solid-state reaction method, and the ceramic samples have been treated by depositing copper films with magnetron sputtering method. The metallic copper films deposited on the ceramic substrates have been mixed at room temperature with argon ions in energy of 400 keV. Ion beam mixing induced modification of PTCR behavior of the ceramics was studied by using the ac complex impedance method and the resistance vs. temperature measurements . The results showed that room temperature resistance dramatically decreased and Curie point shifted toward higher temperature side for the ion beam mixed samples.