Plasma synthesized doped boron nanopowder for magnesium diboride superconductors

用于二硼化镁超导体的等离子体合成掺杂硼纳米粉体

• 批准号: 7220947
• 负责人: James V Marzik
• 金额: $ 7.96万
• 依托单位: SPECIALTY MATERIALS, INC.
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-05-15 至 2008-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7220947
• 关键词: Arts; Boron; Carbon; Characteristics; Chemicals; Chemistry; Communities; Cost Savings; Development; Devices; Diffusion; Electrons; Gases; Goals; Health; Investigation; Lead; Literature; Magnesium; Magnetic Resonance Imaging; Magnetism; Marketing; Measures; Medical; Methods; Modeling; Particle Size; Performance; Phase; Plasma; Powder dose form; Process; Production; Property; Reaction; Reporting; Research; Route; Sampling; Societies; Source; Structure; Technology; Temperature; Titanium; Tube; Variant; Work; base; boron trichloride; cost; density; desire; improved; interest; magnesium boride (MgB2); magnetic field; nanopowder; nanoscale; nanosized; present value; programs; research study; silicon carbide; size; solid state

DESCRIPTION (provided by applicant): Controlled chemical doping of magnesium diboride (MgB2) has been shown to substantially improve superconducting properties to the levels required for high field magnets, but consistent dopant concentrations and homogeneity are difficult to accomplish through the usual route of solid state reaction and diffusion. Furthermore, a high quality source of doped boron needs to be established to advance the state of the art and to ultimately commercialize MgB2 superconductors. Gas phase plasma synthesis of boron powder in which dopants and boron are atomically mixed in the plasma will produce nano-sized batches of doped boron powder. Initial experiments using plasma synthesis methods proved satisfactory to prepare carbon-doped boron powders suitable for the fabrication of high performance MgB2 conductors. At 20 K, critical current density (Jc) values of 100,000 A/cm2 were obtained at 2 Tesla and at 5 K, Jc values of 100,000 A/cm2 were obtained at 4-5 Tesla. Upper critical magnetic field (Hc2) values as high as 37 tesla were achieved. In Phase I, an investigation of carbon, titanium, and silicon carbide as dopant additions to boron powder will be carried out to improve on the above properties. The plasma synthesis method will be used for powder production and the effect of dopant chemistry and concentration on the properties of boron powder will be examined. Doped boron powder will be converted to MgB2 superconducting pellets and powder-in-tube wires, and the superconducting properties will be measured. The effect of powder particle size, purity, dopant concentration, and chemical homogeneity on the superconducting properties of MgB2 will be investigated. Chemically doped magnesium diboride (MgB2) superconducting magnets can perform at least as well as NbTi and NbSn3 in high field magnetic fields and still offer an improvement over the latter in terms of operating temperature. These characteristics make doped MgB2 an effective material for medical MRI devices. Cheaper and more efficient medical MRI devices could lower examination costs, find potential health problems earlier, and thus benefit society as a whole.

描述（由申请人提供）：二硼化镁（MgB2）的受控化学掺杂已被证明可以显着提高超导性能，达到高场磁体所需的水平，但通过通常的固态途径很难实现一致的掺杂剂浓度和均匀性反应和扩散。此外，需要建立高质量的掺杂硼源以推进现有技术并最终实现 MgB2 超导体的商业化。硼粉的气相等离子体合成，其中掺杂剂和硼在等离子体中原子混合，将产生纳米级批量的掺杂硼粉。使用等离子体合成方法的初步实验证明，制备适合制造高性能 MgB2 导体的碳掺杂硼粉末是令人满意的。在 20 K 下，在 2 Tesla 下获得了 100,000 A/cm2 的临界电流密度 (Jc) 值；在 5 K 下，在 4-5 Tesla 下获得了 100,000 A/cm2 的 Jc 值。上临界磁场 (Hc2) 值高达 37 特斯拉。在第一阶段，将研究碳、钛和碳化硅作为硼粉末的掺杂剂添加物，以改善上述性能。等离子体合成方法将用于粉末生产，并将检查掺杂剂化学和浓度对硼粉末性能的影响。掺杂硼粉末将转化为MgB2超导颗粒和管内粉末线，并测量其超导性能。将研究粉末粒径、纯度、掺杂剂浓度和化学均匀性对 MgB2 超导性能的影响。化学掺杂二硼化镁 (MgB2) 超导磁体在高场磁场中的性能至少与 NbTi 和 NbSn3 一样好，并且在工作温度方面仍比后者有所改进。这些特性使掺杂 MgB2 成为医疗 MRI 设备的有效材料。更便宜、更高效的医用核磁共振设备可以降低检查成本，更早发现潜在的健康问题，从而造福整个社会。