Plasma Synthesized Doped Boron Nanopowder for MgB₂ Superconductors

Technical Report · Mon Mar 26 00:00:00 EDT 2012

DOI:https://doi.org/10.2172/1036975· OSTI ID:1036975

Marzik, James V. ^[1]

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1. Specialty Materials, Inc., Lowell, MA (United States)

Under this program, a process to synthesize nano-sized doped boron powder by a plasma synthesis process was developed and scaled up from 20 gram batches at program start to over 200 grams by program end. Over 75 batches of boron nanopowder were made by RF plasma synthesis. Particle sizes were typically in the 20-200 nm range. The powder was synthesized by the reductive pyrolysis of BCl₃ in hydrogen in an RF plasma. A wide range of process parameters were investigated including plasma power, torch geometry, gas flow rates, and process pressure. The powder-in-tube technique was used to make monofilament and multifilament superconducting wires. MgB₂ wire made with Specialty Materials plasma synthesized boron nanopowder exhibited superconducting properties that significantly exceeded the program goals. Superconducting critical currents, J_c, in excess of 10⁵ A cm^-2 at magnetic fields of 8 tesla were reproducibly achieved. The upper critical magnetic field in wires fabricated with program boron powder were H_c2(0) = 37 tesla, demonstrating the potential of these materials for high field magnet applications. T_c in carbon-doped MgB₂ powder showed a systematic decrease with increasing carbon precursor gas flows, indicating the plasma synthesis process can give precise control over dopant concentrations. Synthesis rates increased by a factor of 400% over the course of the program, demonstrating the scalability of the powder synthesis process. The plasma synthesis equipment at Specialty Materials has successfully and reproducibly made high quality boron nanopowder for MgB₂ superconductors. Research and development from this program enabled Specialty Materials to successfully scale up the powder synthesis process by a factor of ten and to double the size of its powder pilot plant. Thus far the program has been a technical success. It is anticipated that continued systematic development of plasma processing parameters, dopant chemistry and concentration, wire processing technology, and collection technology will lead to the commercialization of boron nanopowder as a precursor for MgB₂ superconductors. Potential commercial applications include magnets for magnetic resonance imaging (MRI), fault current limiters, wind turbine generators.

• Research Organization: Specialty Materials, Inc., Lowell, MA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), High Energy Physics (HEP)
• DOE Contract Number: FG02-06ER84478
• OSTI ID: 1036975
• Report Number(s): DOE-ER--84478
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
43 PARTICLE ACCELERATORS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
77 NANOSCIENCE AND NANOTECHNOLOGY
BORON
CARBON
CHEMISTRY
COMMERCIALIZATION
CRITICAL CURRENT
GAS FLOW
GEOMETRY
HYDROGEN
MAGNETIC FIELDS
PARTICLE SIZE
PILOT PLANTS
PLASMA
PRECURSOR
PYROLYSIS
SUPERCONDUCTING WIRES
SUPERCONDUCTORS
SYNTHESIS
critical superconducting current
high temperature superconductor
magnesium diboride
nano-sized powder
superconductor
upper critical magnetic field