Optimization of Nominal Mixing Ratio of Mg to B in Fabrication of Magnesium Diboride Bulk

Author

Zhang, Yun ; Lu, Cheng ; Zhou, Si Hai ; Chung, Kookchae ; Li, Wen Xian

Author_Institution

Inst. for Supercond. & Electron. Mater., Univ. of Wollongong, Wollongong, NSW, Australia

Volume

19

Issue

3

fYear

2009

fDate

6/1/2009 12:00:00 AM

Firstpage

2775

Lastpage

2779

Abstract

In this paper bulk magnesium diboride (Mg_xB₂) with x varying from 0.9 to 1.3 was prepared by solid state reaction. The Mg:B mixing ratio for ideal MgB₂ is 1:2. The samples were sintered at 800degC for 60 h. Quantitative X-ray diffraction (XRD) analysis was performed to obtain the lattice parameters, the microstrain, and the weight fraction of impurities using the Rietveld refinement method. It has been found that the fraction of pure MgB₂ phase increases from x = 0.9 to x = 1.1, and then decreases with further increases in x. Mg_1.1B₂ exhibits the highest critical current density, J_c, over other samples in both low fields and high fields. A direct correlation between J_c and connectivity indicates that better connectivity, caused by smaller amounts of impurities, results in the best J_c in Mg_1.1B₂.

Keywords

X-ray diffraction; critical current density (superconductivity); impurities; lattice constants; magnesium compounds; materials preparation; sintering; superconducting materials; MgB₂; Rietveld refinement method; critical current density; impurities; lattice parameters; microstrain; nominal mixing ratio; quantitative X-ray diffraction analysis; sintering; solid state reaction; temperature 800 C; time 60 h; weight fraction; ${rm MgB}_{2}$; Connectivity; nominal mixing ratio; superconductivity;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/TASC.2009.2017700

Filename

5067257