强电用超导材料的发展现状与展望

超导材料具有常规材料不具备的零电阻、完全抗磁性等宏观量子现象，是典型的量子材料。在强电应用领域，使用超导材料可以实现常规技术无法实现的超强磁场、大容量储能等诸多颠覆性技术，因此，强电用超导材料制备技术一直是国际高技术竞争前沿。本文通过梳理国内外强电用超导材料及其制备技术的发展现状，系统分析和阐明了包括低温超导材料NbTi、Nb3Sn和高温超导材料YBCO涂层导体、Bi-2223带材、Bi-2212线材以及MgB2线材等实用化超导材料在强电应用领域的发展趋势。分析我国强电用超导材料发展存在的问题，我国需要以开发出面向不同强电应用需求的高性能超导材料体系为基础，实现超导材料和强电应用产品的协同发展，推动强电用超导材料制备技术和应用技术的创新水平提升和产业化规模。研究建议，通过国家层面组织“产学研用”联合攻关，实现低温超导材料产业升级，突破高温超导材料批量化制备关键技术的发展思路，实现强电用超导材料的快速发展和应用。     

高温超导线材及其强电应用研发与产业发展状况

上世纪九十年代末,高温超导材料的制备技术取得重大突破,高温超导线材很快形成产业化生产能力,极大地促进了超导应用技术的研究。发达国家政府加大了对超导技术产品研发的支持力度,国际跨国公司,如:SIMENS、ABB、牛津仪器、Pirelli、住友等,也加快了超导技术产品的研发,超导应用技术发展迅速。本文将对高温超导线材及其几个强电应用的国内外研发与产业发展状况作一介绍。     

实验新发现挑战高温超导理论

美国康奈尔大学的研究人员通过单原子尺度的观测，发现高温超导机制可能比科学家们想象的更接近于低温超导。超导是能不受有效电阻作用传导电流的材料。被称为铜氧化物的高温超导材料可以在相对较高的液氮温度下实现超导。这项最新研究可能对理解高温超导机制有帮助。     

高温超导磁储能(SMES)磁体直接冷却热输运过程研究

随着高温超导材料与低温技术的发展，采用制冷机直接冷却已经成为高温超导应用的发展方向，而界面热阻则直接影响着超导器件的冷却效率和运行可靠性，因此减小和控制低温界面热阻是实现超导系统直接冷却的技术关键。对直接冷却高温超导磁体从室温冷却到49K低温的热输运过程进行了理论分析和实验研究，磁体冷却实验结果和理论分析符合较好，通过直接冷却实验所达到的最低温度特性和过程分析，证实从微结构低温工程学的角度研究界面热阻、探索超导直接冷却最佳热耦合机制是高温超导应用基本而重要的科学问题之一。     

超导电力应用的进展

综述国外低温超导材料和高温超导材料及其在同步发电机、电力变压器、电力电缆、电力贮能装置、限流器等电力设备中应用的进展情况。     

高温超导材料及其应用前瞻

高温超导材料产业化进程的不断加快使得超导材料的应用领域越来越广。本文分别描述了第一代与第二代高温超导带材的优劣势等,并对其应用前景进行了分析,详细介绍了超导材料在超导电机、超导电缆等领域的应用情况,并对高温超导材料未来的应用前景进行了分析。     

欧洲超导技术考察报告

在国家863三个五年计划的支持下,我国在超导技术领域进行了广泛的研究,高温超导应用基础研究和实用成材技术方面处于国际先进行列。但是,超导应用的研究与工程化方面与国际水平有较大的差距。 这种背景下,如何确定我国超导技术领域发展的战略与重点;作为政府,如何更有效地推动我国超导技术的发展,是我们面临的问题。为此,北京市科委和北京英纳超导技术有限公司、北京云电英纳超导技术有限公司、北京中数威利超导技术有限公司的有关同志,参加了第五届欧洲超导应用大会,并考察了丹麦NKT公司、德国西门子公司超导研究部、德国Karlsruhe研究中心。考察的目的是:（1）了解欧洲超导技术研究与产业化发展态势;（2）了解欧洲各国在项目组织与管理中的有效做法。现将有关情况做一介绍,并就国内超导技术产     

低温技术在高温超导(HTS)电力系统中的应用

阐述低温技术在超导电力系统中的制冷机支接冷却技术、液氮迫流循环系统以及基于Peltier材料的Peltier冷却方法等几个重要应用。指出用微低温工程学(micro-nanocryogenics)观点研究三维低温界面层和界面层热阻对高温超导动态稳定性的影响是高温超导电力应用低温技术的研究热点及重要研究方向之一。     

高温超导磁悬浮车研究进展

从1911年发现超导现象至今,新型超导材料不断涌现。随着临界温度及内部磁通钉扎性能不断提升,实用型超导磁悬浮技术成为可能。首先介绍了当前主要的磁悬浮交通模式及其特点,具体包括常导电磁悬浮(EMS,Electromagnetic Suspension)、低温超导电动磁悬浮(LTS EDS,Low-Temperature Superconducting Electrodynamic Suspension)、及高温超导磁悬浮(HTS Maglev,High-Temperature Superconducting Magnetic Levitation)。其次,针对高温超导磁悬浮,重点阐述了其自稳定悬浮原理、发展历程以及相关实验样车研究现状。2014年6月西南交通大学将高温超导磁悬浮与真空管道相结合,成功搭建了新一代的真空管道高温超导磁悬浮车试验平台"Super-Maglev",以期探讨高温超导磁悬浮未来可能的交通模式与技术定位等问题。最后,总结了高温超导磁悬浮相比于其他磁悬浮模式的优势,并进一步讨论了可能的轨道交通应用速度等级。     

超导在空间技术中的应用（一）

简介了超导技术在空间技术中的应用情况。其中还包括高温超导材料的空间热处理的国内研究结果的概述。在超导的具体空间应用中介绍了超导陀螺、空间超导磁体系统、超导助推发射装置、空间超导贮能、超导天线、空间用的超导电子器件的应用情况.     

“122”体系铁基超导线带材研究进展

简单介绍了“122”体系铁基超导材料的物理性能及优点,详细综述了“122”体系铁基超导线带材的研究进展,如制备方法、临界电流密度影响因素,并展望了“122”体系铁基超导线带材今后的研究方向.     

Bi系高Tc超导体动态热膨胀反常行为理论初探

从理论上探讨了高Ｔｃ超导体的动态热膨胀反常行为，对正常态和超导两组参数拟合实验数据，结果基本吻合。与正常态相比，超导态的非诺性增强，原子间相互排斥的不对称性和声子的软化现象均增强，尤其是声子的软化更为显著。此结果有助于理解高Ｔｃ超导电性机理。     

Oxygen Processing of Hg and Tl Based Cuprate Superconductors

The effect that oxygen stoichiometry has on the physical properties of high critical temperature superconductors is well documented. For a general understanding of the conditions necessary for processing high critical temperature superconducting materials, phase equilibrium diagrams have been quite useful; however, such diagrams provide no information concerning the time required to oxygenate superconducting structures. In this paper, we present experimental results that clearly demonstrate the relationships among phase equilibrium diagrams, oxygen diffusion coefficients and grain sizes with the time required to adequately oxygenate high critical temperature superconducting materials and device structures. While oxygen processing of the high critical temperature superconductor, YBa₂Cu₃O_7–, is emphasized throughout this paper, the concepts and relationships discussed herein, in general, can be applied to the oxygen processing of other high critical temperature superconductors including the Hg and TI based systems.where the investigations were conducted has been transferred to the U.S. Army Research LaboratoryD.M. Pierce: Work performed while a National Research Council Associate     

Semiconductor-superconductor hybrid electronics

This paper examines the feasibility and potential for applications of intimately combining semiconductor and superconductor devices at circuit and system levels. The focus is mainly on the temperature range 27–77 K. One of the main issues is the heat produced by the semiconductor devices, since the superconductor devices produce much less heat and are sensitive to temperature changes. It is shown that Josephson junctions made with high temperature superconductors can be placed very close to transistors on a properly heatsunk chip. A second important issue is interfacing the low voltages of superconducting devices to the much higher voltages needed for transistors; an existing technique is discussed in the context of high temperature superconductors. Only well developed semiconductor technologies have been considered; although there is some possibility of making low voltage transistors, this is not explored here. The paper concludes with an analysis of the various applications that can be realized, depending on the type of device available in high temperature superconductor technology: passive patterned films, nonhysteretic Josephson devices or Josephson tunnel juntions.     

Bi系高温超导体的能量吸收及反常热膨胀

从理论上探讨了高Tc超导体正常态和超导态的不同能量吸收机制及动态热膨胀反常行为.     

Normal zone initiation in composite superconductors

The initiation of superconducting state instability in composite superconductors due to heat disturbances is investigated. The instability development results as a rule in the transition of the superconductor into the resistive state and normal zone propagation along the conductor. It is shown that in the case of high current density, thick conductors and poor cooling the heat power necessary to initiate the instability may be small compared to the heat power necessary to warm the superconductor to the temperature of the resistive transition.     

Review of Thermal Boundary Resistance of High-Temperature Superconductors

Solid-solid thermal boundary resistance plays an important role in the thermal stability of many electronic circuits, microdevices, and superconducting devices. The thermal boundary resistance (R _b ) at any interface causes a temperature discontinuity, which can result in heat accumulation on one side of the boundary and raise the temperature much above the stable region, causing device failure. With the advent of high-critical-temperature (high-T _c ) superconductors, it is possible to make superconducting devices at practically achievable temperatures. As the current trend goes toward the development of more and more high-T_c superconducting devices, the need for a better understanding of the thermal boundary resistance of high-T_c superconductors becomes mandatory. This paper compiles all the theoretical and experimental work to date onR _b in high-T_c superconductors, both in thin-film and bulk forms, and provides a critical review of the cited works. This paper also describes the possible effect of the superconducting state onR _b for high-T _c superconductors, based on the experiments for both high-T_c and low-T_c bulk superconductors, and a possible explanation for these data based on the existing theory for low-T _c superconductors.     

Granularity and Linear Flux Dynamics in Sintered LaO0.92F0.08FeAs

The flux dynamics in LaO_0.92F_0.08FeAs polycrystalline samples has been investigated looking at the first and higher harmonics of the AC magnetic susceptibility. The investigation of the real and imaginary part of the first harmonic shows that the critical temperature is reduced when the applied DC field increases. Moreover, the intergrain and intragrain contributions persist up to the highest applied DC field, suggesting that the electromagnetic connection among the superconducting grains is strong in spite of the estimated very short coherence length. Concerning the higher harmonics, a comparison between the absolute value of the real part of the first harmonic and the sum of the higher harmonics clearly indicates the activation of a linear regime below the superconducting critical temperature. Furthermore, the temperature range where this linear regime is activated is smaller than the one found in cuprate perovskite superconductors.      

Effect of interlayer interaction in high-Tc cuprate superconductors

We have studied the role of interlayer attractive interaction in a high-T _c system having two layers per unit cell. The single band two-layer tight binding model Hamiltonian is considered and the double time Green's function technique is applied within the mean field approximation. The expressions for the hole density, transition temperature, and intra- and interlayer order parameters are obtained which are found to be dependent on the interlayer interaction and other parameters appearing in the Hamiltonian. The numerical analysis shows that the coupling of the charge carriers (holes) between the layers provides better conditions for the stabilization of long-range order and high superconducting transition temperature in layered superconductors. It is also observed that superconductivity is confined to a narrow region of hole concentration and the single particle tunneling suppresses the transition temperature.     

Evaluation of the electron-phonon interaction and transition temperature in the oxide superconductors

The Allen-Dynes equation applicable to the oxide superconductors is studied, which shows that for moderate values of the electron-phonon coupling constant the superconducting transition temperature is found in the range of 100 K. This result is based on an approximate evaluation of large values of the McMillan-Hopfield parameter and evidence from frozen-phonon calculations that strong ionic character in the copper oxide superconductors invalidates the rigid muffintin approximation.