High Performance Bi-2212 Round Wires Made with Recent Powders

Area of Science:

• Materials Science
• Condensed Matter Physics
• Superconductivity

Background:

• Multifilamentary Bismuth Strontium Calcium Copper Oxide (Bi-2212) wire is the only high-temperature superconductor available in a round shape, ideal for magnet construction.
• The powder-in-tube technique is used to manufacture Bi-2212 wire.
• Significant improvements in critical current density (Jc) for Bi-2212 round wire have been achieved through overpressure heat treatment.

Purpose of the Study:

• To investigate the impact of precursor powder composition and heat treatment parameters on the superconducting properties of Bi-2212 wires.
• To analyze the microstructural characteristics of Bi-2212 wires subjected to optimized processing conditions.
• To evaluate the performance of recent Bi-2212 wires for potential applications in high-field magnets.

Main Methods:

• Fabrication of Bi-2212 wires using the powder-in-tube method.
• Application of optimized overpressure heat treatment processes.
• Characterization of superconducting properties, including critical current density (Jc) at various magnetic fields and temperatures.
• Microstructural analysis of the processed Bi-2212 wires.

Main Results:

• Short samples of Bi-2212 wire processed with optimized overpressure conditions demonstrated high critical current densities.
• Achieved Jc values at 4.2 K were 6640 A/mm² at 15 T and 4670 A/mm² at 30 T.
• Engineering critical current densities were reported as 1320 A/mm² at 15 T and 930 A/mm² at 30 T (4.2 K).

Conclusions:

• Optimized overpressure heat treatment significantly enhances the superconducting performance of Bi-2212 round wires.
• The improved critical current densities make Bi-2212 wire a highly promising conductor for demanding applications like very high-field NMR and accelerator magnets.
• Bi-2212 wire is commercially available in long lengths and various architectures, facilitating its use in magnet technology.