A review is given for the development of theories for superconductivity in order to give a proper perspective for the theory to clarify the mechanism of high-Tc superconductivity in copper oxides. A preliminary result for the doped fullerenes is also mentioned.
Nb3Sn in the form of practical superconductors has been avilable for years. At present, the principal techniques employed are bronze and internal tin processes. Nb3Sn has exhibited high performance at high magnetic field. Porosity in the Nb3Sn superconductors is often observed after the reaction treatment and can be detrimental to the mechanical and electrical properties. Voids, probably due to the Kirkendall effect, could be annihilated by heating under high pressure. Therefore, the hot isostatic pressing (HIP) could improve the properties. The author reviewed the effects of HIPping on the porosity and the critical current of Nb3Sn superconductor produced both by the bronze process and internal tin processes.
The applications of high pressure to high - Tc oxide superconductors are reviewed. High pressure is very powewful for synthesizing of new materials and understanding of the physical properties. Studies of HIP treatment on Y124 and high pressure synthesis of “infinite - layer” materials are introduced. Pressure dependence of both Tc and Hall coefficients of the material are discussed in relation with carrier doping effects on the physical properties.
In this review, we take briefly a historical survey of the high pressure techniqes which have been used in the research for superconductivity and then report some experimental results of the pressure effect on the superconducting transition temperature in various superconducting materials.
It is reviewed that how the high pressure technique and physics have played an essential role for the development of the field of the organic superconductors. It is described historically from TTF - TCNQ through TMTSF to BEDT - TTF salts making emphasis on how discoveries have been guided. Pressure apparatus of the author for this research is also presented.
Superconductivity is being widely applied in advanced technology programs, such as nuclear fusion reactor, superconducting power generators and energy storage, MRI - diagnosis, and magnetically levitated vehicles. High performance multifilamentary wires such as NbTi, (Nb, Ti) 3Sn, V3Ga and Nb3Al are being developed. High - Tc superconducting materials such as YBaCuO, BiSrCaCuO, and TlBaCaCuO have attracted a great interest in regard to the basic properties and potential applications in liquid nitrogen. Even though many problems still remain to be solved, remarkable progress is being achieved and some new applications are being offered. The development of the high - Tc materials will lead to a complete reassessment of superconducting technologies.
Extensive studies on the effect of a low intensity magnetic field on microbial activity have been reported. However, they are often controversial; the magentic fields are accelerative on the growth, or inhibitory, or noneffective. The inconsistency of the results is mainly because the experimental conditions were improperly controlled and well characterized microbial strains were not used. Following the invention of superconductive materials, high magnetic fields produced by superconductive magnets will be applicable to various microbial reaction control. In this paper, a super high magetic field of 11. 7 tesla (T) was imposed on the auxotrophic bacteria of Escherichia coli and the effect of the magnetic field was investigated under various nutritional and temperature conditions. The 11. 7 T was also imposed on E. coli where the bacteriophage lambda was lysogenic and carries a temperature-sensitive mutation in the phage repressor gene. The transition from lysogenic to lytic process was investigated. A new bioreactor which was operated under 7 T superconductive magnetic field was introduced.
Shock loading effects on various superconducting materials, placing emphasis on high Tc oxides, are summarized. Synthesis of superconductors via shock-induced phase transitions and chemical reactions, shock compaction of powder materials for fabrication of bulk superconductors, and shock deformation via defects and dislocations have been discussed. Shock loading effects and subsequent annealing effects on superconducting critical temperatures and flux pinning energy of high Tc oxides are elucidated.
The electric conductivities of electrolyte solutions under high pressure are reviewed. First, the measurements of conductivity and transference number under high pressure are described briefly. Second, the interpretation of ionic conductivities in water in terms of the Walden product and the residual friction coefficient is presented. Finally, the pressure and isotope effects on the excess proton conductivity are discussed based on the Conway model.
The utilization of the energy of a supersonic water jet outflowing from a small-diameter hole under high pressure makes a progressive advance in material cutting. The history of the high pressure water jet technology applied to many fields as well as mechanical engineering has been surveyed briefly, and recent investigations and progress in the technology have been reviewed by classifying the technology into nine jets under cutting mechanism.
Failure and fracture of high pressure apparatus result in occasionally the most dangerous accidents in laboratory and manufacturing plant. Elastic failure, bursting, brittle fracture and fatigue fracture are briefly reviewed.
Diamond-anvil-cell is a very powerful device for studing pressure-induced phase transition and chemical reaction by spectroscopy such as Raman scattering and IR absorption. Very thin diamond anvils and pressure transmitting mediums used for IR measurement are described.