脉冲电沉积制备InSb/Sb超晶格纳米线阵列

采用脉冲电沉积技术在氧化铝模板中制备得到直径60 nm的InSb/Sb超晶格纳米线阵列,并运用扫描电镜、透射电镜和电子能谱仪对其形貌与结构进行了表征与测试。高度有序的InSb/Sb超晶格纳米线长度约为40 μm,其长径比超过600。实验中,通过改变沉积电压与时间达到了对超晶格纳米线组分与结构的控制, 纳米线阵列中In与Sb的原子质量比接近于1/2,在每个周期中,InSb的厚度为12 nm,Sb相似文献   

巨介电材料的研究进展

随着电子工业的发展,为了满足电容器、存储器、谐振器、滤波器等重要电子器件的高性能化和尺寸微型化的需求,高介电常数材料越来越引起人们的重视。研制出新型的高介电常数材料,在宽频、宽温范围内,既具备高介电常数和低介质损耗,又有良好的频率和温度稳定性,是高容量电容器发展的需要。本文对现有的介电材料进行总结,并揭示了其巨介电机理。     

钛酸钡基铁电材料的介电非线性研究

通过A位或B位掺杂改性得到的钛酸钡基铁电材料,在外加直流偏置电场作用下,具有介电常数非线性可调的优异介电性能,可以广泛地应用于压控可调陶瓷电容器和微波可调器件领域。针对钛酸钡基铁电材料的介电非线性特性,讨论了BaTiO_3基铁电材料分别在铁电相、顺电相以及相转变温度场附近的介电非线性机理和相关理论;结合笔者近年来有关介电非线性研究的实验结果和相关文献报道,综述了不同A位离子(如Sr~(2-)和Ca~(2-)等)或B位离子(如Zr~(4 )和Sn~(4-)等)掺杂的BaTiO_3基铁电材料体系的介电非线性研究现状,分别对不同物质形态(陶瓷块体、薄膜和厚膜)的BaTiO_3基铁电材料的介电非线性研究及其应用进行了对比分析;并对钛酸钡基铁电材料今后的发展趋势和研究方向进行了展望。     

聚合物/石墨烯介电复合材料研究进展

石墨烯具有超高的电导、热导率和比表面积,逾渗阈值很低,是一种理想的介电填充改性材料。综述了近年来国内外聚合物/石墨烯介电复合材料研究进展,指出将导电填料掺入聚合物基体中以制备具有轻质和优异介电性能的复合材料被认为是最有前途的工艺之一,高效实现石墨烯在聚合物中的均匀分散、解决界面缺陷、降低漏电流仍是今后的主要研究方向。     

铅基复合钙钛矿型驰豫铁电体介电理论研究进展

复合钙钛矿型驰豫铁电体是一类具有重要应用价值的铁电材料，有关其介电特性的研究不仅具有重要的理论意义，而且具有十分重要的实用价值。本文综述了铅基复合钙钛矿型驰豫铁电体介电理论研究进展。     

钛酸铜钙巨介电材料的研究进展

CaCu_3Ti_4O_(12)(CCTO)材料以巨介电常数、低介电损耗等性能成为研究热点。该文主要介绍了CaCu_3Ti_4O_(12)材料的结构、巨介电机理、制备方法和掺杂改性,并简要叙述了材料的应用前景。     

石油介电谱的研究进展

阻抗谱或者介电谱测量是一种迅速的、非侵入的测量手段。国外的石油方向研究学者对介电技术的应用十分广泛。本文针对原油生产与运输中常见的问题,综述了介电谱在石油科学领域的研究进展:沥青质发生聚集或者絮凝前后,油样的介电性质会发生显著变化;原油乳状液稳定性与其电学性质密切相关;原油的流动性质与其电学性质之间存在定量关系。最后本文推荐了今后研究的方向:介电的角度研究蜡对原油流变性质的影响。     

介孔材料合成研究进展

介孔材料具有比表面积大、孔径结构均一和可调等优良性能,在催化、吸附、分离、传感器以及光、电、磁等领域具有潜在的应用价值。综述了介孔材料的研究进展,介绍了介孔材料的分类、合成方法、合成机理及其应用。阐述了液晶模板、电荷匹配、棒状自组装、层状折皱模型和协同作用等介孔材料的合成机理,对介孔材料进行了展望。     

Influence of Uniaxial Tensile Stress on the Mechanical and Piezoelectric Properties of Short-period Ferroelectric Superlattice

Tetragonal ferroelectric/ferroelectric BaTiO₃/PbTiO₃\hbox{BaTiO}_3/\hbox{PbTiO}_3 superlattice under uniaxial tensile stress along the c axis is investigated from first principles. We show that the calculated ideal tensile strength is 6.85 GPa and that the superlattice under the loading of uniaxial tensile stress becomes soft along the nonpolar axes. We also find that the appropriately applied uniaxial tensile stress can significantly enhance the piezoelectricity for the superlattice, with piezoelectric coefficient d ₃₃ increasing from the ground state value by a factor of about 8, reaching 678.42 pC/N. The underlying mechanism for the enhancement of piezoelectricity is discussed.     

几种典型的微波介质陶瓷材料的研究现状

微波介质陶瓷是现代通信技术快速发展的关键材料.按照应用领域的不同,介绍了几种典型的微波介质陶瓷,详细探讨了各种体系下微波介质陶瓷烧结性能的特点,并指明了今后微波介质陶瓷的发展方向.     

微波介质陶瓷的研究现状及其粉末合成方法

微波介质陶瓷作为微波介质滤波器、微波介质谐振器及微波介质振荡器的重要材料,是现代通信技术中关键基础材料,它的研究越来越受到人们的重视。本文综述了目前微波介质陶瓷的主要三种结构体系,并且介绍了微波介质陶瓷的国内外研究现状,粉体的制备以及存在的问题和未来发展趋势。     

介电性弹性体的研究进展

综述了介电弹性体的种类、性能、制备方法与主要发展方向,概述了介电弹性体驱动性能的表征方法,提出了制备高介电低模量介电弹性体的几点建议。     

钛酸铅微晶玻璃介电性能研究

主要对钛酸铅系铁电性微晶玻璃的介电性能做了研究,研制的微晶玻璃初始组成由形成主晶相的氧化物和形成玻璃相的氧化物构成,经过熔融、热处理可以得到以钛酸铅为主晶相的微晶玻璃,分析了不同组成情况下微晶玻璃的介电性能.     

Dielectric relaxation spectra of chemically treated woods

The changes in the dielectric properties of absolutely dried Sitka spruce (Picea sitchensis Carr.) wood caused by chemical treatments were investigated. Eight kinds of chemical treatments with various levels of weight percentage gain (WPG) were performed. Through the application of the Cole–Cole circular arc law to the results of the dielectric measurements in the frequency range of 1 kHz to 1 MHz at ?60°C, the relaxation spectrum was calculated. The relaxation magnitude (ε₀ ? ε_∞) was reduced by formalization, acetylation, propylene oxide, and phenol–formaldehyde resin treatments, in which chemical reactions occurred between the OH groups in the cell wall and the added reagents. On the other hand, the generalized relaxation time (τ_m) decreased with increasing WPG, except for acetylation, for which τ_m decreased up to a WPG level of 20% and then increased. In poly(ethylene glycol) impregnation, (ε₀ ? ε_∞) decreased with increasing WPG up to about 50% and then increased, whereas τ_m linearly decreased with increasing WPG. No significant changes in these parameters were recognized for the wood methyl methacrylate composite and heat treatment. With the steam treatment, τ_m increased. The distribution of the relaxation times was broad in acetylation and narrow in propylene oxide treatment and poly(ethylene glycol) impregnation. However, it remained almost unchanged in the other treatments. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 37–43, 2005     

ZrO2制备方法研究进展

以ZrO₂为活性组分或载体的催化剂,在酚类定向催化转化中具有较高的研究价值。总结了ZrO₂的各种制备方法,包括溶胶-凝胶法、共沉淀法、水热法、表面活性剂辅助法、静电纺丝法、热解法、多元醇还原法、反相微乳法和超临界合成法等。阐述了各种方法的反应原理,详细比较了不同制备方法的优劣,并具体分析了制备方法对催化剂结构及性能的影响。     

微波介质陶瓷的研究进展

综述了微波介质陶瓷材料的特性和发展现状,给出了多数目前已经研究的微波陶瓷体系及其性能,阐述了其制备方法,提出了改善其性能的途径和微波介质陶瓷的预期进展.     

几种典型的低介硅酸盐微波陶瓷材料的研究现状

概述了MgO-SiO2,Zn2SiO4,CaSiO3和Re2O3-SiO2(Re=稀土元素)等低介电常数硅酸盐微波陶瓷材料体系的研究进展.讨论了微波介质陶瓷的结构、微波介电性能、降温方法、机理及其存在的问题,指出了微波陶瓷材料今后的研究方向.     

Dielectric features of two grades of bi‐oriented isotactic polypropylene

The dielectric properties of two grades of bi‐oriented isotactic polypropylene were studied with a variety of techniques: breakdown field measurements, dielectric spectroscopy, thermally stimulated depolarization currents (Is), and direct‐current (dc) conduction I values. Standard polypropylene (STPP) and high‐crystallinity polypropylene (HCPP) films were investigated. Measurements were carried out over a wide temperature range (?150°C/+125°C). The breakdown fields in both materials showed a very small difference. On the other hand, the dielectric losses and dc conduction I values were significantly lower in HCPP. Both materials showed a decrease in the dielectric loss versus temperature in the range 20–90°C; this is favorable for application in alternating‐current power capacitors. The analysis of the dc I value allowed us to find evidence of two main conduction mechanisms: (1) below 80°C in both materials, a hopping mechanism due to the motion of electrons occurred in the amorphous phase, and (2) above 80°C, ionic conduction occurred in HCPP, and hopping conduction occurred in STPP. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42224.