Production and Characterization of Bulk MgB2 Material made by the Combination of Crystalline and Carbon Coated Amorphous Boron Powders

29th International Symposium on Superconductivity

Hiroki, K.^1 ; Muralidhar, M.^1 ; Koblischka, M.R.^2 ; Murakami, M.^1

Superconducting Material Laboratory, Graduate School of Science and Engineering, Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo

135-8546, Japan^1

Institure of Experimental Physics, Saarland University, P.O. Box 151150, Saarbrucken

66041, Germany^2

关键词: Amorphous boron powder;    Argon atmospheres;    Boron and carbons;    Commercial powders;    Current performance;    Magnetization measurements;    Nominal composition;    Single-step process;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/871/1/012058/pdf
DOI  :  10.1088/1742-6596/871/1/012058

来源: IOP

【 摘 要 】

The object of this investigation is to reduce the cost of bulk production and in the same time to increase the critical current performance of bulk MgB2material. High-purity commercial powders of Mg metal (99.9% purity) and two types of crystalline (99% purity) and 16.5 wt% carbon-coated, nanometer-sized amorphous boron powders (98.5% purity) were mixed in a nominal composition of MgB2to reduce the boron cost and to see the effect on the superconducting and magnetic properties. Several samples were produced mixing the crystalline boron and carbon-coated, nanometer-sized amorphous boron powders in varying ratios (50:50, 60:40, 70:30, 80:20, 90:10) and synthesized using a single-step process using the solid state reaction around 800 °C for 3 h in pure argon atmosphere. The magnetization measurements exhibited a sharp superconducting transition temperature with Tc, onsetaround 38.6 K to 37.2 K for the bulk samples prepared utilizing the mixture of crystalline boron and 16.5% carbon-coated amorphous boron. The critical current density at higher magnetic field was improved with addition of carbon-coated boron to crystalline boron in a ratio of 80:20. The highest self-field Jcaround 215,000 A/cm2and 37,000 A/cm2were recorded at 20 K, self-field and 2 T for the sample with a ratio of 80:10. The present results clearly demonstrate that the bulk MgB2performance can be improved by adding carbon-coated nano boron to crystalline boron, which will be attractive to reduce the cost of bulk MgB2material for several industrial applications.