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Full-Text Articles in Engineering
Stress/Strain Induced Flux Pinning In Highly Dense Mgb2 Bulks, Rong Zeng, S X. Dou, Lin Lu, Wenxian Li, Chung-Kiak Poh, Jung Ho Kim, Josip Horvat, Dongqi Shi, Jianli Wang, Paul G. Munroe, X. F. Wang, Rongkun Zheng, S. P. Ringer, M Rindfleisch, Mike Tomsic
Stress/Strain Induced Flux Pinning In Highly Dense Mgb2 Bulks, Rong Zeng, S X. Dou, Lin Lu, Wenxian Li, Chung-Kiak Poh, Jung Ho Kim, Josip Horvat, Dongqi Shi, Jianli Wang, Paul G. Munroe, X. F. Wang, Rongkun Zheng, S. P. Ringer, M Rindfleisch, Mike Tomsic
Faculty of Engineering - Papers (Archive)
We have systematically studied the flux pinning behavior of MgB2 bulks synthesized by direct diffusion of Mg into pressed pellets of high purity crystalline B powder, with and without mixing with C and SiC nanoparticles, at a reaction temperature of 850degC for 10 hrs. All of the samples showed very high purity and high density, but their microstructure and flux pinning behavior showed significant differences. It was found that the pure MgB2 agrees with the deltaTc pinning model, nano-C doped MgB2 agrees with the deltal pinning model, while the SiC+MgB2 composite agrees …
Increased Superconductivity For Cnt Doped Mgb2 Sintered In 5t Pulsed Magnetic Field, Wenxian Li, Ying Li, Rong Hua Chen, Rong Zeng, Lin Lu, Yun Zhang, Michael Tomsic, Matthew Rindfleisch, S. X. Dou
Increased Superconductivity For Cnt Doped Mgb2 Sintered In 5t Pulsed Magnetic Field, Wenxian Li, Ying Li, Rong Hua Chen, Rong Zeng, Lin Lu, Yun Zhang, Michael Tomsic, Matthew Rindfleisch, S. X. Dou
Faculty of Engineering - Papers (Archive)
The superconductivity of carbon nanotube (CNT) doped MgB2 sintered in pulsed magnetic field (PMF) was investigated with Raman scattering measurements and Raman spectral fit analysis. Although the carbon (C) substitution for the boron (B) is increased for the sample sintered in PMF, its superconductivity is advanced comparing with the sample sintered without PMF. The improved critical transition temperature, Tc, is attributed to the strengthening of the electron-phonon coupling (EPC) in MgB2, as reflected by the broadened E 2g mode in the Raman spectra, because the carbon atoms are homogeneously distributed in the boron planes.
Influence Of Heat Treatment On Superconductivity Of Mgb2 Bulk Sintered In Flowing Welding Grade Ar Atmosphere, Yun Zhang, Cheng Lu, Sihai Zhou, K. C. Chung, Y. K. Kim, S. X. Dou
Influence Of Heat Treatment On Superconductivity Of Mgb2 Bulk Sintered In Flowing Welding Grade Ar Atmosphere, Yun Zhang, Cheng Lu, Sihai Zhou, K. C. Chung, Y. K. Kim, S. X. Dou
Faculty of Engineering - Papers (Archive)
In this paper, MgB2 samples were sintered in flowing welding grade Ar. The effect of the sintering time varying from 10 minutes to 3 hours on superconductivity of MgB2 has been investigated. It has been found that both Hc2 and Hirr increase with the sintering time and they have linear relationships with microstrain. The sample sintered for 30 min exhibits the highest Jc at high fields. The reason can be attributed to the improved connectivity and the increased Hc2.
A Comparative Study On Field, Temperature, And Strain Dependences Of The Critical Current For Doped And Undoped Mgb2 Wires Based On The Percolation Model, Sangjun Oh, Jung Ho Kim, Kyuhwan Cho, Chulhee Lee, Chan-Joong Kim, S. X. Dou, M Rindfleisch, Mike Tomsic, Jung-Ho Ahn
A Comparative Study On Field, Temperature, And Strain Dependences Of The Critical Current For Doped And Undoped Mgb2 Wires Based On The Percolation Model, Sangjun Oh, Jung Ho Kim, Kyuhwan Cho, Chulhee Lee, Chan-Joong Kim, S. X. Dou, M Rindfleisch, Mike Tomsic, Jung-Ho Ahn
Faculty of Engineering - Papers (Archive)
Field, temperature, and strain dependences of the critical current for a SiC doped multifilamentary in situ MgB2 wire have been studied. Measurement results were compared with that of the undoped wire, and the origin of the difference in the critical current is discussed. The critical current can be calculated with the percolation model considering the effect of anisotropy. The temperature dependence of the fitting parameters, the upper critical field along the ab-plane, and c-axis is compared with the dirty-limit two-gap theory. To assess the validity of the fitting parameters, resistive transition has been measured especially to …
Preparing Mgb2 With Excessive Mg Environment Sintering And Two-Step Sintering Approach, S X. Dou, Sihai Zhou, Alexey V. Pan, Jaimoo Yoo, Yun Zhang, Kookchae Chung
Preparing Mgb2 With Excessive Mg Environment Sintering And Two-Step Sintering Approach, S X. Dou, Sihai Zhou, Alexey V. Pan, Jaimoo Yoo, Yun Zhang, Kookchae Chung
Faculty of Engineering - Papers (Archive)
MgB2 superconductors were made with two processes in this work. In one case, the SiC doped MgB2 pellets were sintered in excessive Mg medium. It is found that the samples sintered in excessive Mg medium present Mg-rich composition comparing with the one sintered in Ar gas. The density is higher and the resistance is lower due to the penetration of the Mg into the pores and grain boundary of MgB2, which is beneficial to the Jc improvement. In the other case, a two-step process was employed to make MgB2. Jc of the …
Thermal-Strain-Induced Enhancement Of Electromagnetic Properties Of Sic-Mgb2 Composites, Rong Zeng, S X. Dou, Lin Lu, Wenxian Li, Jung Ho Kim, Paul G. Munroe, Rongkun Zheng, S P. Ringer
Thermal-Strain-Induced Enhancement Of Electromagnetic Properties Of Sic-Mgb2 Composites, Rong Zeng, S X. Dou, Lin Lu, Wenxian Li, Jung Ho Kim, Paul G. Munroe, Rongkun Zheng, S P. Ringer
Faculty of Engineering - Papers (Archive)
The effect of thermal strain caused by the different thermal expansion coefficients (α) of the MgB2 and SiC phases on the electromagnetic properties was studied for SiC–MgB2 composite, which was made by premixing SiC and B, followed by Mg diffusion and reaction. Thermal strain in the MgB2 phase was demonstrated with x-ray diffraction, Raman spectroscopy, and transmission electron microscopy. In contrast to the common practice of improving the critical current density Jc and the upper critical field Hc2 of MgB2 through chemical substitution, by taking advantage of residual thermal strains, we …