Dielectric Behavior of Nano-PbTiO3/PVDF Nanocomposites In-situ Synthesized by the Sol-gel Method

PbTiO3 / PVDF nanocomposites were prepared via in-situ growth of nanosized PbTiO3 particles in PVDF matrix by sol-gel method. Nanosized PbTiO3 grown in the composites film was characterized by X-ray diffractometry （XRD） and transmission electron mieroscopy, and the dielectric properties of the composite films prepared were measured. The distribution of PbTiO3 nanoparticles in-situ grown in the PVDF matrix was examined using a scanning electron microscope. The relative dielectric eonstant increases with increasing the weight fracture of PbTiO3 in-situ grown. In particular, the dielectric loss monotonically decreases with the increase of PbTiO3 content at 1 MHz.     

The Dielectric Properties and Preparation Method of BaTiO_3/PVDF 0-3 Composites

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Dielectric Behavior of BaTiO3／ PVDF Nanocomposites In-situ Synthesized by the Sol-Gel Method

BaTiO3/ PVDF nanocomposites were prepared via in-situ growth of nanosized BaTiO3 particles in PVDF matrix by using the sol-gel method. The present elements of BaTiO3/ PVDF nanocomposites were analyzed by an electron probe X-ray microanalyser. Nanosized BaTiO3 grown in the composite films was characterized by an X-ray diffractometer and a transmission electron microscope, and the dielectric properties of the composite films were measured. The distribution of BaTiO3 nanoparticles in-situ grown in the PVDF matrix was examined using a scanning electron microscope.     

PbTiO3/PVDF复合材料介电性能及压电性能研究

实验制备了 Pb Ti O3/ PVDF复合材料 ,测试了频率对复合材料介电性能的影响 ,并分析了 Pb Ti O3的体积分数与复合材料介电性能的关系 ;研究了复合材料的压电性能 ;并对样品微观形态进行了分析。     

The Dielectric Properties and Preparation Method of BaTiO3/PVDF 0-3 Composites

A series of 0-3 composties of the polyvinylidene fluoride (PVDF) and BaTiO3 was prepared,BaTiO3 was modified with titanate coupling agent .The dielectric properties and the interfacial interaction of composites by different preparation methods were examined and compared,The result shows that the relaive dielectric constant ε of the composite prepared in solution has a maximum value at about 70% weight fraction of BaTiO3 and the dielectric loss tanδ increases rapidly when the fraction exceeds 70%, For the composite preared in melt, the relative dielectric constant ε almost raches a maximum value at about 60% weght fraction of BaTiO3 and the dielectric loss is comparatively lower,The deielectric proerties of composites ore improved by using a coupling aent.     

银/聚偏氟乙烯电介质复合材料性能研究

采用溶液共混法制备银(Ag)/聚偏氟乙烯(PVDF)复合材料,研究了Ag粉体积分数及粒径对复合材料介电性能、击穿场强等的影响。结果表明,复合材料的介电常数随填料的体积分数的增加而增大,当Ag粉体积分数为17%时最佳,之后介电常数开始下降。在Ag粉体积含量相同条件下,添加小粒径Ag粉比大粒径Ag粉更有利于提高复合材料介电性能。X射线衍射分析结果表明,Ag在复合材料制备过程中无分解及氧化,适量填充Ag粉有助于复合材料击穿场强的提高。     

BiFeO3薄膜的溶胶-凝胶制备及其铁电和介电性质

采用Bi(NO3)3.5H2O和Fe(NO3)3.9H2O为原料,用溶胶-凝胶方法在Pt/Ti/SiO2/Si制备了BiFeO3薄膜。XRD研究表明在500℃以上退火薄膜能够获得良好的结晶。铁电性测试结果表明450℃和500℃退火的薄膜铁电性相对较弱。在430 kV/cm的测试电场下,剩余极化分别为0.255μC/cm2和0.36μC/cm2。而550℃和600℃退火的薄膜的铁电性相对较强,在相同的测试电场下剩余极化强度分别为2.27μC/cm2和2.97μC/cm2。介电性研究表明450—550℃退火的薄膜具有小的介电色散和介电损耗,而600℃退火的薄膜则具有大的介电色散和介电损耗。     

聚氨酯/钛酸钡杂化材料及介电性质研究

通过溶胶-凝胶法制备了一种新型的聚氨酯/钛酸钡(PU/BaTiO3 )杂化材料--不同钛酸钡含量的聚氨酯/钛酸钡杂化材料.通过红外光谱(FTIR)、扫描电镜(SEM)和光电子能谱(XPS)等手段,考察了杂化材料的结构与性能;详细研究了溶胶-凝胶过程的机理以及微波辐射后杂化材料的介电性能.结果表明:通过溶胶-凝胶法制备的PU/BaTiO3杂化材料中PU和BaTiO3形成了较强的化学作用,而不是简单的共混;BaTiO3较均匀分散在杂化材料中,同时随着BaTiO3含量的增加,材料的介电常数也逐渐增加.指出了该研究在油气田领域的应用前景及意义.     

溶胶-凝胶法制备BST/MgO陶瓷及其介电性能

为获得致密细晶、介电性能优良的BST/MgO陶瓷,采用溶胶-凝胶法制备包裹MgO粉体的BST凝胶.凝胶预烧温度为750℃,粉体烧结工艺为1300℃保温2 h.实验结果表明该方法制备出的BST/MgO陶瓷包含BST和MgO两相,无任何杂相,陶瓷晶粒生长完整且均匀,气孔呈现圆形,相对密度达92.4%,具有良好的介电性能.     

固／液相合成法制取高纯微细钛酸钡

用初级二氧伦钛和碳酸钡为原料，经提纯、活化，洪沉淀形成ＢａＣＯ３．ＴｉＯ２固＝固包裹体，煅烧等工序后，低成本高质量地制备高纯微细电子级钛酸钡粉体。     

温度和水的加入量对Sol-Gel法制备钛酸钡的影响

研究了Sol-Gel法制备钛酸钡粉的过程中,不同的加热温度和不同的Ti^4＋与水的摩尔比例对溶胶-凝胶的形成速率以及最终制备出来的钛酸钡粉体粒径大小的影响。并在50℃的加热温度和水-Ti^4＋摩尔比为1∶10,烧结温度为800℃的条件下,制备出了平均粒径为44.2093 nm的钛酸钡纳米粉。     

钇离子掺杂BaTiO3基电容器陶瓷制备及性能研究

以BaCO3和TiO2为原料、Y2O3为添加剂制备了Y3＋离子掺杂BaTiO3基电容器陶瓷试样。采用XRD和SEM技术分析了试样的物相和陶瓷的显微结构,测试了Y3＋离子掺杂BaTiO3基电容器陶瓷系列试样的介电性能。结果表明,当Y3＋离子掺杂浓度为0.3mol%时,在1310℃保温时间为2h时,可制备介电常数为13965.4,介质损耗为0.110的BaTiO3基电容器陶瓷材料。     

BT/PANI/PVDF复合材料的制备及介电性能

为提高电介质材料的介电性能,采用原位聚合的方法制备了BT/PANI复合功能体,以其为功能相,制备了BT/PANI/PVDF三相复合材料.采用红外光谱法和X射线衍射法对BT/PANI复合功能体的结构进行了表征,采用扫描电子显微镜和阻抗分析仪对BT/PANI/PVDF三相复合材料的微观形貌和介电性能进行了表征.分析了BT/PANI/PVDF体系中的极化方式,并以此为基础,对介电性能随频率的变化规律进行了解释.结果表明:在BT/PANI/PVDF三相复合体系中,功能相BT/PANI被均匀包覆在聚合物基体中,得到了介电性能较好的BT/PANI/PVDF三相复合材料.     

Cr粒子含量对Al2O3/Cr复合材料力学性能及介电性能的影响

以热压烧结的方法制备了Al2O3／Cr复合材料，探讨了Al2O3／Cr复合材料显微结构、力学性能及微波介电性能随Cr粒子含量变化的规律。SEM结果表明，在垂直于压力方向上，Cr粒子有明显的受压拉伸现象；当Cr粒子含量从10vol％增加至30vol％时，复合材料中Cr粒子的分布由孤立向桥连方式转变。随Cr粒子含量的增加，复合材料致密度略有下降，抗弯强度明显降低。与纯氧化铝陶瓷相比，含10vol％Cr粒子Al2O3／Cr复合材料的断裂韧性提高了81％以上。复介电常数测试结果表明，在8．2～12．4GHz频率范围内，复合材料复介电常数的实部和虚部随Cr粒子含量的增加大幅度上升，且存在明显的频散效应。当Cr粒子含量达到30vol％时，由于Cr粒子之间的部分桥连现象而使介电常数虚部在一定频段出现负值。     

Ba（Zr0．06 Ti0．94）O3－BiFeO3复合陶瓷的介电、铁电及压电性能研究

采用高温固相法制备出Ba（Zr0．06Ti0．94）O3－x％BiFeO3（x＝0．2,0．4,0．6,0．8）系列复合陶瓷,并研究了其相结构、介电、铁电和压电性质．XRD结果表明,所有样品均呈现典型的钙钛矿四方相结构,而样品的晶格常数随着BiFeO3的含量改变发生了一定变化．介电－温度图谱表明,复合陶瓷的相变温度和介电常数都受到了BiFeO3成分影响,室温介电常数随着BiFeO3含量的增加不断增大,并且复合陶瓷中存在弥散相变．所有样品均显示出明显的铁电与压电特性,并且随着BiFeO3含量变化,两种特性呈现出相同的变化趋势．     

Dispersing and Doping of BaTiO3 Powder by Adsorption

Dispersing and doping of BaTiO3 powder by adsorption method were investigated.Ultrafine BaTiO3 powders were dispersed in the aqueous with ammoniumized citrate (NH4-CA) or ammoniumized citric Ianthanum chelate (NH4-La-CA) as dispersant by ultrasonic bath. Better dispersion of BaTiO3 slurry was obtained in the aqueous with NH4-La-CA than that of NH4-CA when the mass ratio of citric acid (CA) to BaTiO3.Was less than 0.007. The pH value hardly affects the dispersion property of BaTiO3 suspension dispersed by NH4-La-CA. BaTiO3 powder could be well dispersed (median size D50=0.45 μm) and also doped with high uniformity of added components by adsorbing citric acid chelate on surface. Compared with solid mixing, better microstructure and properties of La/Mn codoped ceramics were obtained by adsorption method.     

铁磁性 Mn-Zn、Ni-Zn 铁氧体与铁电性 BaTiO_3 复合材料吸收电磁波能力研究

本文研究了铁磁性Ｍｎ－Ｚｎ、Ｎｉ－Ｚｎ铁氧体与铁电性ＢａＴｉＯ３复合材料在１～１０００ＭＨｚ频段内的吸波能力。结果表明：随频率升高,Ｍｎ－Ｚｎ铁氧体／ＢａＴｉＯ３和Ｎｉ－Ｚｎ铁氧体／ＢａＴｉＯ３复合材料的吸波能力逐渐增加;随Ｍｎ－Ｚｎ或Ｎｉ－Ｚｎ铁氧体含量增加,这两类复合材料的吸波能力也逐渐增加;相同配比时的Ｎｉ－Ｚｎ铁氧体／ＢａＴｉＯ３复合材料吸波能力大于Ｍｎ－Ｚｎ铁氧体／ＢａＴｉＯ３。     

Sintering and dielectric properties of fine-grained BaTiO_3 ceramics

A new sintering method, spark plasma sintering (SPS), is described for the sintering of fine-grained BaTiO_3 ceramics. Dense ceramics with fine grain size of near 170 nm are obtained using SPS at low temperature of 900℃ without holding time. The dielectric measurements of various grain size specimens show that the dielectric constants decrease with the reduce of grain size, and diffuse phase transition showed in the dielectric-temperature spectra. The variation in dielectric properties with grain size is explained.     

聚苯胺/镍纳米复合材料原位复合与性能表征

采用先合成导电聚苯胺,然后用多元醇原位液相还原的方法,合成了聚苯胺/镍纳米复合材料,纳米镍的含量约为19.22%(质量分数)。具有面心立方晶体结构,生成的纳米镍“镶嵌”在聚苯胺颗粒的表面,形成了类似“草莓”状的复合颗粒,复合颗粒的热稳定性有较明显提高。复合颗粒同时具有铁磁性和导电性,复合颗粒的饱和磁化强度最高可达到10.77Am2/kg,电导率为9.86×10-3S/cm。     

粉末合成温度对BaTiO3基PTCR性能的影响

由固相反应法制备的BaTiO3基PTCR热敏陶瓷,研究了BaTiO3粉末合成温度对粉末粒度分布、陶瓷电性能和显微组织结构的影响.XRD分析的结果表明,在1 000 ℃/4 h下焙烧的粉末已经是纯钙钛矿结构的BaTiO3;而粒度分布分析结果反映出,当焙烧温度高于1 050 ℃时,粉末开始出现团聚现象;SEM分析发现随着粉末焙烧温度的提高,烧结后BaTiO3陶瓷的晶粒变细.电性能测试结果表明1 000 ℃时焙烧粉末所制备的陶瓷电性能最好.综合分析表明:1 000 ℃是粉末合成的最佳温度,有利于获得低室温电率阻、高升阻比的PTCR陶瓷.