Carbon doping has proven to be a highly effective strategy for enhancing the electrical properties of MgB2 wires, especially under a high magnetic field. However, unreacted doping material can persist as impurities due to uneven mixing or incomplete reactions, thereby detrimentally affecting electrical properties and their uniformity. In this study, we explore the application of pyrene doping to 18-multifilamentary MgB2 wires with a total length of 2.5 kilometers. The aim of this study is to minimize residues and maximize high-field critical current properties. Our investigation includes X-ray diffraction refinement, scanning electron microscopy observations, and a comprehensive characterization of critical current properties. We are presently evaluating the viability of applying this doping material and method in large-scale commercial production.
Abstract
Evaluation and control of amorphous phases in materials are very important for optimizing their properties. Herein, we focus on polycrystalline MgB materials prepared with hydrocarbon doping and study the effects of residual amorphous impurities on the superconducting performance. Carbon is known to be an effective element for enhancing the transport critical current under an external magnetic field. The doped samples were prepared under two different nominal conditions, MgB (C H ) and MgB (C H ) , which respectively correspond to additional and substitutional type doping of the MgB composition. Regardless of the doping type, both fabrication methods retarded the formation of the MgB phase due to the dopant, leading to an increase in amorphous impurities. However, the apparent phenomena that arise from the additional and substitutional types are still elusive. Ultimately, the structural differences due to the impurity effects caused significant changes in the transport
Abstract
It is demonstrated experimentally and confirmed theoretically that highly defective boron nitride showed outstanding performance for oxidative dehydrogenation of ethylbenzene. The catalyst is derived from carbon-doped hexagonal boron nitride nanosheets synthesized via a two-step reaction when participating the oxidative dehydrogenation reaction. The first step yields a polymeric precursor with the atomic positions of B, C, N relatively constrained, which is conducive for the formation of carbon atomic clusters uniformly dispersed throughout the BN framework. During the oxidative dehydrogenation of ethylbenzene to styrene, the nanoscale carbon clusters are removed and highly defective boron nitride (D-BN) is obtained, exposing boron-rich zigzag edges of BN that act as the catalytic sites. The catalytic performance of D-BN is therefore remarkably better than un-doped h-BN. Our results indicate that dispersed C-doping in h-BN is highly effective in terms of defect formation an