Ab initio Computational Study of Electronic Structure and Effect of Applied Pressure on Superconducting Properties of NB3SN and TI; NB3SN

Abstract

Abstract Superconducting magnets have been in demand due to their high magnetic fields and high currents. In high-field magnets, particularly those used in Magnetic Resonance Imaging and the International Thermonuclear Experimental Reactor, as well as in transmission cables, mechanical loading during cool down due to thermal contractions of the material is very large. This can lead to poor performance of Niobium-Tin since it is a major component of the magnetic coils, whose superconducting performance is affected by pressure. Similarly, Niobium Tin made by the internal tin process during fabrication still has significant potential in performance. To achieve this potential, the concept was re-examined and optimized for the future needs of High Energy Physics. The idea in this thesis originated from re-examining the concept of internal tin, recognizing what has been learned on its strengths and weaknesses, and using that knowledge to propose a high-performance conductor suitable for various strains and conditions, while still maintaining its high current density. Niobium-Tin was doped with Titanium, and the end product was subjected to pressure to study how much strain it can withstand. The study reveals that Niobium Tin is dynamically stable and brittle, and highly susceptible to pressure-induced changes, while Titanium-doped Niobium Tin shows enhanced resistance to deforming stress. These outcomes indicate that Titanium doping significantly improves the mechanical robustness and overall performance of the conductor under pressure. The study reports the electronic structure and elastic properties, which provide information on the material’s stability, dynamic properties, and pressure-induced superconducting properties of Niobium-Tin and Titanium-doped Niobium-Tin (Ti; Nb3Sn). The study was conducted using a computational method, specifically the Density Functional Theory Method, and applied the open-source software Quantum ESPRESSO code. Niobium Tin is a superconductor. The key outcome is that Titanium-doped Niobium Tin is a better-performing conductor compared to undoped Niobium Tin under mechanical stress, suggesting it is more suitable for practical applications in superconducting magnets. An experimental study of the effect of pressure on Niobium Tin and Titanium-doped Niobium Tin is recommended.