高温超导体中的正常态能隙——兼评近一年来高温超导电性基础研究的新进展

简介了有关弱掺杂高温超导体正常态中的能隙或赝隙研究的情况，扼要评述了近一年来高温超导电性基础研究的一些进展，包括与高温超导相关的一些新材料和新现象     

高温超导电性的电子配对机制

高温超导电性的电子配对机制阎新中（中国科学院物理研究所，北京１０００８０）１０年前，人们首次发现了高温超导材料［１］．从此之后，对高温超导电性的研究成了凝聚态物理的热点领域．通过大量的实验和理论探索，人们在合成新的高温超导材料以及对高温超导机制的认...     

钕铁硼在高温超导磁悬浮技术实验中的应用

将新材料钕铁硼作为磁导轨引入到高温超导磁悬浮技术实验中,介绍了高温超导悬浮技术实验的基本原理、仪器及钕铁硼对实验的改进.     

高温超导体中的正常态能隙

简介了有关弱掺杂高温超导体正常态中的能隙或赝隙研究的情况，扼要评述了近一个来高温超导电性基础研究的一些进展，包括与高温超导相关的一些新材料和新现象。     

不含稀土元素的高温超导体

氧化物高温超导材料La2-xMxCuO4-y(M为Ba,Sr或Ca)和ReBa3Cu3O7-y或大部分稀土元素)的发现,是超导电性研究的一个重要的里程碑.这类材料晶体结构的特点是含有二维Cu-O2平面层,人们认为高温超导电性与此密切相关.因此,晶体结构中含有这种Cu-O2平面层的新材料可望是高温超导体.最近,人们用Bi或T1替代上面两类材料中的稀土元素,合成出了新的稳定的高温超导材料,从而在这个以Cu-O2平面层为结构特征的高温超导家族中又添加了新的成员. 1987年五月,法国Caen大学的C.Michel和B.Raveau等人报道了他们的发现[1]:在接近Bi2Si2Sr2Cu2O7 y成…     

高温超导薄膜微波非线性研究的进展

文章介绍了高温超导薄膜微波非线性的主要特征，阐述了高温超导薄膜微波非线性产生的原因和相关的研究现状，指出了高温超导薄膜非线性研究中遇到的困难和尚未解决的问题．     

铊系高温超导体的化学、晶体结构,材料特征及生产工艺

本文回顾了铊系高温超导体的发现及人们在合成不同的铊系高温超导材料方面取得的成果,并从晶体结构和化学成分两个方面论证了铊系高温超导材料的多样性和丰富性.在化学组成上,铊系高温超导家族是最大的超导家族.铊系高温超导体的晶体结构类型几乎包括了所有铜基氧化物高温超导体具有的晶体结构.高质量高性能的铊系高温超导材料的制备方法也在文中进行了论述.     

1989年美国物理学会年会简讯

3月20日至24日,美国物理学会在圣路易斯市(Saint Louis)举行了1989年春季年会.会议中有20%的论文与高温超导有关.物理学家们就高温超导理论进行了专题讨论.理论学家进一步阐述了安德森(Anderson) 的共振共价键理论.朱经武(休斯顿大学)和吴茂昆(哥伦比亚大学)的科研组分别报告了新的实验结果.会议中,人们就高温超导应用进行了认真的讨论.科学家们还渐认识了高温超导体的电、磁与光学特征.穆斯堡效应与其它测量技术提供了新材料的结构信息.本届会议还就固体物理的其它分支学科进行了研究和讨论.论文主要集中于半导体、低温超流、磁性材料与…     

冷绝缘高温超导电缆绝缘设计的研究

目前随着国内外高压输电系统的不断发展,许多研究机构一直试图开发高电压等级的高温超导电缆系统,这就要求设计的HTS电缆要有可靠的绝缘性能和优化的绝缘设计技术.根据超导电缆的结构特点和高温超导电缆系统的运行特点,对Nomex和PPLP进行了交流耐压、雷电冲击、局部放电(PD)起始电压和热循环等高压绝缘特性试验.根据不同厚度...     

应用超导研究中心

应用超导研究中心，致力于高温超导强电和弱电基础和应用研究。2001年4月中心研制的Bi系高温超导导线，被评为2001年中国十大科技新闻.2002年研制成功我国第一台移动通信用的高温超导滤波器系统。2004年高温超导滤波器系统在中国联通基站应用成功，实现了我国高温超导研究18年后的首次实际应用，也使我国成为继美国之后将高温超导应用于移动通信的第二个国家。2005年在北京建成了我国第一个高温超导移动通信应用示范基地。2005年Bi系导线的制备和大规模应用获得北京市科技进步一等奖。应用超导研究中心     

High pressures: Recent trends in materials science

Abstract

Pressure was developed during the 20th century. The most important illustration of the use of high pressure in Materials Science was the synthesis of diamond at the beginning of the fifties.

This contribution will describe the main scientific research axis developed these last years and based on high pressure (synthesis of new materials, stabilization of specific structures, crystal-growth, preparation of finely divided materials…).

In parallel some industrial developments will be analyzed.

In conclusion, the potential of high pressure will be sketched for the near future.     

Kinetics of phase transitions under high pressure

Abstract

Phase transitions under high pressure have attracted increasing attention i n connection with high pressure synthesis of new materials (e.g. superhard materials, ceramics, semiconductors, high temperature superconductors) and the exploration of geological processes like the formation of rocks and minerals. For t h e investigation of thermodynamic and electronic equilibrium properties a broad spectrum of methods for pressure generation and physical measurements have been developed ^1,2,3,4. Tha measurement of equilibrium properties, however, gives only poor insight into the detailed mechanisnts of phase changes. The accurate determination of phase equilibria and phase diagrams becomes inore and more difficult a t low temperatures due to increasing hysteresis effects end t h e extrapolation of experimental data to zerc, teiiipwature a nd the compar ison with quantumiiiechanical ah in.itio calculations are questionable.     

New quantum matters: Build up versus high pressure tuning

In this article we briefly review new quantum functional compounds primarily based on our recent works.We will highlight the effects of pressures on both materials synthesis and quantum tuning.The contents include(I)"111"-type iron based superconducting system,(II)pressure induced superconductivity in topological insulators and(III)the new diluted magnetic semiconductors with decoupled spin charge doping.     

高压合成立方氮化硼用的新触媒材料的研究

 本文研究了合成立方氮化硼用新触媒材料Mg₃B₂N₄及Ca₃B₂N₄的制备方法，并对它们的稳定性及其催化作用进行了讨论。氮化硼原料的结晶状态及合成温度、合成时间、气流量等对新触媒的合成有着重要的影响。本文还在高温高压下利用新触媒进行了立方氮化硼的合成实验，结果表明，与碱土金属触媒相比新触媒具有合成压力低、转化率高、合成温度和压力范围宽、产物杂志含量低、破碎强度高等优点，是一种应用前景很大的触媒材料。     

High pressure structural phase transitions of TiO_2 nanomaterials

Recently, the high pressure study on the TiO_2 nanomaterials has attracted considerable attention due to the typical crystal structure and the fascinating properties of TiO_2 with nanoscale sizes. In this paper, we briefly review the recent progress in the high pressure phase transitions of TiO_2 nanomaterials. We discuss the size effects and morphology effects on the high pressure phase transitions of TiO_2 nanomaterials with different particle sizes, morphologies, and microstructures. Several typical pressure-induced structural phase transitions in TiO_2 nanomaterials are presented, including size-dependent phase transition selectivity in nanoparticles, morphology-tuned phase transition in nanowires, nanosheets,and nanoporous materials, and pressure-induced amorphization(PIA) and polyamorphism in ultrafine nanoparticles and TiO_2-B nanoribbons. Various TiO_2 nanostructural materials with high pressure structures are prepared successfully by high pressure treatment of the corresponding crystal nanomaterials, such as amorphous TiO_2 nanoribbons, α-PbO_2-type TiO_2 nanowires, nanosheets, and nanoporous materials. These studies suggest that the high pressure phase transitions of TiO_2 nanomaterials depend on the nanosize, morphology, interface energy, and microstructure. The diversity of high pressure behaviors of TiO_2 nanomaterials provides a new insight into the properties of nanomaterials, and paves a way for preparing new nanomaterials with novel high pressure structures and properties for various applications.     

High-pressure synthesized materials: treasures and hints

This short review covers some particular aspects of the production of new materials under high pressures. Despite the fact that there is an extremely wide range of new high-pressure synthesized substances with unique properties, a commercial synthesis has been used up to date only for producing superhard materials – these are real treasures of today’s industry. At the same time, as should be underlined here, high-pressure experiments often give scientists material with helpful hints of what new intriguing substances can exist in principle. This is true both for new superhard, semiconducting, magnetic, superconducting, optical materials already synthesized under pressure and a large number of hypothetic new polymers from low-Z elements.     

High dynamic pressures and applications in materials science

Abstract

The high dynamic pressure behaviour of materials is, for many years, of great interest either for scientific studies (equation of state, Hugoniot and off Hugoniot, phase transitions …) or for industrial applications (synthesis of new materials, hardening, welding, powder compaction, jet cutting…

These different aspects are presented and these capabilities certainly will be an important factor in the next future.     

高压下限域富勒烯分子体系构筑的新结构

探索新的碳结构是物理、材料等学科关注的热点课题. 富勒烯分子可看成是一种零维碳结构，其独特的结构和优异的性质为构筑新碳结构提供了理想的构筑单元. 本文介绍了利用限域与高压相结合的方法，在富勒烯限域体系研究中取得的进展，包括溶剂化富勒烯、富勒烯填充单壁碳纳米管（Peapod）限域体系的高压结构转变，总结了溶剂分子等对限域富勒烯高压结构相变与新结构形成的影响. 结果对新型碳结构的设计与构筑提供了新的思路与有益参考.     

Controllable synthesis of fullerene nano/microcrystals and their structural transformation induced by high pressure

Fullerene molecules are interesting materials because of their unique structures and properties in mechanical, electrical, magnetic, and optical aspects. Current research is focusing on the construction of well-defined fullerene nano/microcrystals that possess desirable structures and morphologies. Further tuning the intermolecular interaction of the fullerene nano/microcrystals by use of pressure is an efficient way to modify their structures and properties, such as creation of nanoscale polymer structures and new hybrid materials, which expands the potential of such nanoscale materials for di- rect device components. In this paper, we review our recent progress in the construction of fullerene nanostructures and their structural transformation induced by high pressure. Fullerene nano/microcrystals with controllable size, morphology and structure have been synthesized through the self-assembly of fullerene molecules by a solvent-assisted method. By virtue of high pressure, the structures, components, and intermolecular interactions of the assemblied fullerene nano/microcrystals can be finely tuned, thereby modifying the optical and electronic properties of the nanostructures. Several examples on high pressure induced novel structural phase transition in typical fullerene nanocrystals with C60 or C70 cage serving as build- ing blocks are presented, including high pressure induced amorphization of the nanocrystals and their bulk moduli, high pressure and high temperature （HPHT） induced polymerization in C60 nanocrystals, pressure tuned reversible polymeriza- tion in ferrocene-doped C60/C70 single crystal, as well as unique long-range ordered crystal with amorphous nanoclusters serving as building blocks in solvated C60 crystals, which brings new physical insight into the understanding of order and disorder concept and new approaches to the design of superhard carbon materials. The nanosize and morphology effects on the transformations of fullerene nanocrystals have also been discussed. These results provide the foundation for the fabrication of pre-designed and controllable geometries, which is critical in fullerenes and relevant materials for designing nanometer-scale electronic, optical, and other devices.     

Synthesis of Highly Stable One-Dimensional Black Phosphorus/h-BN Heterostructures:A Novel Flexible Electronic Platform

Layered black phosphorus(BP) has recently emerged as a promising semiconductor because of its tunable band gap,high carrier mobility and strongly in-plane anisotropic properties.One-dimensional(1 D) BP materials are attractive for applications in electronic and thermal devices,owing to their tailored charge and phonon transports along certain orientations.However,the fabrication of 1 D BP materials still remains elusive thus far.We herein report the successful synthesis and characterization of nanotube-like BP for the first time by a selective composite with hexagonal boron nitride(h-BN) nanotubes under high pressure and high temperature conditions.The produced 1 D BP/h-BN composites possess flexible diameter,length and thickness by adjusting the experimental synthesis parameters.Interestingly,it is important to notice that the stability of our BP sample has been significantly improved under the formation of heterostructures,which can actively promote their commercial applications.Our experimental work,together with first-principles calculations,presents a new scalable strategy of designing 1 D tube-like BP/h-BN heterostructures that are promising candidates for flexible and high efficiency electronic platform.