Date : November, 2nd      Time : Thursday, 4-5pm      Place : Seminar room: Science 103

Title : Metal-sheathed MgB2 superconducting wires

Speaker : Dr. Gan Liang

Affiliation : Sam Houston State University

Abstract :

Two issues in the metal-sheathed MgB 2 superconducting wires have been studied: (1) the phase formation in the Cu-sheathed MgB 2 wires, and (2) the effects of the SiC doping on the magnetic critical current density ( J c ) of the Ti-sheathed MgB 2 superconducting wires. For Cu0sheathed wire, it is revealed that a new phase -CuMg d phase, is formed in these wires when sintered at temperatures above 712 ºC. Two groups of Ti-sheathed MgB 2 wire samples were prepared and studied: for the first group, the size of the SiC particles was 20 nm and the concentrations were 5%, 10%, and 15%; for the second group, the concentration of the SiC dopant was 10% and the sizes of the SiC particles were 20 nm, 45 nm, and 100-200 nm. Contrary to the J c results reported on the SiC-doped Fe-sheathed MgB 2 wires, we found that the J c for the SiC-doped Ti-sheathed MgB 2 wires decreases with both the concentration and particle size of the SiC dopant. We found that only for the wires with 100-200 nm SiC size, the J c is greater than that of the undoped MgB 2 wires. This unusual dependence of J c on the size and concentration of the SiC dopant is discussed in association with the results from the magnetization, electrical resisitivity, x-ray diffraction and scanning electron microscopy measurements.

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