Crystal growth and characterization of MgB2: Relation between structure and superconducting properties

TL;DR

This paper explores the synthesis, crystal growth, and characterization of MgB2, examining how structural variations and defects influence its superconducting properties, with detailed experimental insights into optimizing growth conditions.

Contribution

It presents new findings on how Mg-deficiency and lattice strain affect MgB2's superconducting properties, along with optimized high-pressure growth techniques.

Findings

Mg-deficiency impacts critical temperature (Tc) and critical current density (Jc)

Lattice strain influences superconducting anisotropy

Optimized P-T conditions enable reproducible crystal growth

Abstract

We discuss the important aspects of synthesis and crystal growth of MgB2 under high pressure (P) and temperature (T) in Mg-B-N system, including the optimisation of P-T conditions for reproducible crystal growth, the role of liquid phases in this process, the temperature dependence of crystal size and the effect of growing instabilities on single crystals morphology. Extensive experiments have been carried out on single crystals with slightly different lattice constants and defects concentration, which revealed and possible effects of Mg-deficiency and lattice strain on the superconducting properties of MgB2 (Tc, Jc, residual resistivity ratio, anisotropy etc.).