Structural and Magnetic Properties of V-Ti-Si Alloy Superconductors

TL;DR

This study investigates how silicon addition affects the structural and superconducting properties of V-Ti alloys, revealing changes in critical temperature, critical field, and phase composition after annealing.

Contribution

It provides new insights into the effects of silicon content and annealing on the superconducting and structural characteristics of V-Ti-Si alloys.

Findings

Silicon addition causes eutectic precipitation of Ti₅Si₃ phase.

Superconducting transition temperature varies non-monotonically with silicon content.

Annealing results in a consistent Tₙ of about 7.7 K across alloys.

Abstract

The structural and magnetic properties of the as-cast and annealed V$_{0.6-x}$Si$_x$Ti$_{0.4}$ ($x$ = 0, 0.05, 0.10, 0.15) alloy superconductors are reported here. It is found that addition of silicon to the V-Ti alloys results in eutectic precipitation of Ti$_{5}$Si$_3$-phase in the body centred cubic (bcc) $\beta$-V-Ti matrix. In the as-cast V$_{0.6-x}$Si$_x$Ti$_{0.4}$ alloys, the superconducting transition temperature (T$_{C}$) changes non-monotonically with increasing silicon content whereas after annealing, it is about 7.7 K for all the alloys. On the other hand, the upper critical field decreases and the coherence length increases after annealing in the x = 0.10 alloy. The variations in the superconducting properties in the alloys are related to the solubility of 6 at.% Si in the V$_{0.60}$Ti$_{0.40}$ alloy and the vanadium enrichment in the $\beta$ matrix due to the precipitation of Ti$_{5}$Si$_3$ phase.