arXiv subjects

H. P. Tang

Publications and source records attributed to H. P. Tang.

3 recordsLinked to original sources

arXiv2006

Improved Superconducting Properties in Bulk MgB2 Prepared by High Energy Milling of Mg and B Powder

The MgB2 bulks were prepared by high energy milling of Mg and B powder. The correlations among milling times, microstructure and superconducting properties were investigated in MgB2 bulks. Samples were characterized by x-ray diffraction (XRD), energy dispersive spectrometry (EDX) and scanning electron microscope (SEM), and the magnetization properties were examined by a Superconducting quantum interfere device (SQUID) magnetometer. It showed that the high energy milling is an effective approach to get fine crystalline (40-100nm) bulk MgB2 with good grain connectivity and high Jc performance. The critical current density reaches to 2.0X10E6A/cm2 at 15K and 0.59T, 5.7X10E5A/cm2 at 2T and 3.0X10E4A/cm2 at 5T.

cond-mat.supr-con↗

arXiv2006

Influence of Preparation Process on Microstructure, Critical Current Density and Tc of MgB2/Fe/Cu Wires

The powder-in-tube MgB2 wires were prepared by high energy milling of Mg and B powder. The powder was not mechanically alloyed for 2h short milling time. However, the MgB2 grains in wires are very small (20 100nm) and resembled to the dimple after post-heat treatment. The clear evidence for transcrystlline fracture is observed. It indicated that the grain connection was greatly improved and the fluxing pinning was significantly enhanced. Another point to view is no intermediate annealing was adopted during the whole rolling process. The influence of the post-heat treatment on the transport current density was studied. Despite the lower Tc of about 35K, the transport current density reaches to 3X10E4A/cm2 at 15K and 3.5T for 700 sintered wires.

cond-mat.supr-con↗

arXiv2006

The Influence of Synthesis Parameters on Microstructures and Superconducting Properties of MgB2 Bulks

We succeeded in the synthesis of high-Jc MgB2 bulks via high energy ball-milling of elemental Mg and B powder at ambient temperatures. Alternatively to longtime mechanical alloying technique, the mixed powder was ball-milled for only 1h and the completed reaction is achieved by subsequent annealing. The correlations among synthesis parameters, microstructures and superconducting properties in MgB2 bulks were investigated. Samples were characterized by XRD and SEM, and the magnetization properties were examined in a SQUID magnetometer. The high- Jc, approximately 1.7*106A/cm2(15K, 0.59T), and improved flux pinning were attribute to a large number of grain boundaries provided by small grain size.

cond-mat.supr-con↗