ニオブ系超伝導体の理解

タイトル: Peculiarities of niobium-based superconducting alloys in the light of crystal chemistry: A brief survey

概要: In this survey, we focus on Nb-based binary intermetallic compounds, which have been widely used over the last 40 years to develop a range of superconducting applications, including non-standard engineering solutions in the design of large magnets. However, since the 1980s, when it became apparent that the mechanical and superior superconducting properties of ordered intermetallic alloys such as Nb$_{3}$Sn were largely due to their unique structural features, much of the research interest in the science of superconducting intermetallic alloys has been redirected to the development of necessary engineering applications in high magnetic field technology. Accordingly, the important role of crystal chemistry in understanding the fundamental aspects of the material properties of the Nb$_{3}$Sn family of intermetallics has been little explored. In the paper, we try to fill this gap by investigating the relationships between composition, microstructure and properties, highlighting their relevance to technological applications. Our goal is to link aspects of crystal chemistry with materials application issues. We shed light on the atomic assembly mechanisms and processes in terms of changes in the chemical environment, lattice structure, crystallization pathway, and macroscale phase textures, which can help in interpreting and explaining the prospects and limitations of the superconducting properties of Nb$_{3}$Sn. In the context of past and present prospects and limitations we briefly overview most important technological applications and discuss the various interrelations between superconductivity and structural properties of Nb-based A-15 intermetallic alloys. We argue that these interrelations can be used to find the Nb-based superconductors with more superior properties and stronger technological usability.