Superconducting Properties and Applications of MgB2 Materials

Since its discovery in 2001, magnesium diboride (MgB2) has garnered attention owing to its superconducting transition temperature of 39 K and its simple binary composition. Its notably high critical current density, relatively low cost of raw materials and favourable grain-boundary characteristics have made the material attractive for both wire and bulk forms. MgB2 exhibits two-gap superconductivity, with distinct σ and π bands contributing to its electromagnetic behaviour. Grain boundaries in polycrystalline MgB2 act as effective flux-pinning sites rather than weak links, enabling excellent current transport in bulk and multifilamentary conductors. Techniques such as chemical doping, pressure-enhanced sintering and liquid-phase fabrication have been used to optimise microstructure, enhance the upper critical field and improve mechanical robustness. Applications span from magnetic resonance imaging and fault-current limiters to rotating machinery, wind-turbine generators and cryogen-free superconducting magnets, with ongoing work targeting further reductions in system mass and operating costs.

Research from Nature Portfolio

Recent studies have shown that carbon-doped bulk MgB2 processed by infiltration and growth can achieve record trapped fields above 4 T at low temperatures. Controlled C incorporation creates nanoscale defects within grains, boosting intra-band scattering and pinning without sacrificing material density. Investigations into ultralightweight MgB2 wires have demonstrated that titanium diffusion barriers and aluminium-based sheaths yield conductors with high critical currents and tensile tolerance, suitable for aerospace and offshore applications. Foundational experiments with high-temperature, high-pressure additions of zirconium, titanium and Dy2O3 have revealed that nano-inclusions induce lattice distortions and secondary precipitates, selectively enhancing upper critical fields and flux pinning.

Superconducting Properties and Applications of MgB2 Materials publication trend

The graph below shows the total number of articles in superconducting properties and applications of mgb2 materials across all publications each year (not limited to Nature Index journals).

Technical terms

Critical current density: The maximum current per unit cross-section that a superconductor can carry without resistance.

Flux pinning: The immobilisation of magnetic vortices at defects or inclusions in a superconductor, preserving zero-resistance flow under applied fields.

Infiltration and growth process: A fabrication method where molten magnesium permeates boron powder matrices to form dense MgB2 microstructures.

Trapped field: The residual magnetic field retained in a superconducting bulk after removal of an external magnetising field.

Critical temperature: The threshold temperature below which a material transitions to a superconducting state and exhibits zero electrical resistance.

References

1. Status of MgB2 wire and cable applications in Europe. Journal of Physics Conference Series (2017).
2. High Trapped Fields in C-doped MgB2 Bulk Superconductors Fabricated by Infiltration and Growth Process. Scientific Reports (2018).
3. Ultra-lightweight superconducting wire based on Mg, B, Ti and Al. Scientific Reports (2018).
4. Influence of Metal Diboride and Dy2O3 Additions on Microstructure and Properties of MgB2 Fabricated at High Temperatures and under Pressure. Scientific Reports (2016).
5. Improving the connectivity of MgB2 bulk superconductors by a novel liquid phase sintering process. Superconductor Science and Technology (2022).
6. Microstructures and superconducting properties of MgB2 bulk samples processed by ultra-high pressure-assisted sintering. Journal of the European Ceramic Society (2022).
7. Synthesis of Dense MgB2 Superconductor via In Situ and Ex Situ Spark Plasma Sintering Method. Materials (2021).