Low temperature formation of superconducting MgB2 phase from elements by mechanical milling

The influence of the mechanical milling of the corresponding powder elements on the formation of superconducting MgB2 phase was investigated. Mg and B powders were attrition-milled, and then the milled powder mixture was annealed under atmospheric pressure of argon. MgB2 phase clearly appeared after annealing the 60 min milled powder mixture at 500 degreesC. This powder mixture showed much larger diamagnetism magnitude at 4 K than that was milled for 5 min. The structural analyses revealed that the superconducting phase in this powder was formed at the Mg and B composite structure which was fabricated by the longer mechanical milling. These results indicate that the mechanical milling of the powder elements can enhance the reactivity for the formation of MgB2. (C) 2003 Elsevier B.V. All rights reserved.