An electrochemical technique has been introduced and applied to fabricate superconducting MgB2 films in molten salts. MgCl2, Mg（BO2）2, NaCl, and KCl were used as electrolyte, graphite was used as the anode, and copp...An electrochemical technique has been introduced and applied to fabricate superconducting MgB2 films in molten salts. MgCl2, Mg（BO2）2, NaCl, and KCl were used as electrolyte, graphite was used as the anode, and copper was used as the cathode, respectively. X-ray diffraction （XRD） analysis was chosen to investigate the phase composition and crystallinity of the films at different electrolysis temperatures. Stan- dard four-probe technique and SQUID were applied to investigate the temperature dependence of resistance （R-T） properties and magnetic properties of the films, respectively. The results indicate that MgB2 films have been fabricated on the copper cathodes, and superconducting transition takes place close to 50 K.展开更多
Using commercial amorphous B powder (92% in purity) and Mg powder (99% in purity) as starting materials, 19-filament Fe/Cu clad MgB2 wires were fabricated by an in situ powder-in-tube method. Heat treatment was perfor...Using commercial amorphous B powder (92% in purity) and Mg powder (99% in purity) as starting materials, 19-filament Fe/Cu clad MgB2 wires were fabricated by an in situ powder-in-tube method. Heat treatment was performed at 700℃ for 1 h under an argon gas atmosphere. The influence of Mg/B ratio on the microstructure and superconducting properties of the wires was investigated. It was found that the major phases of MgB2 wires were MgB2 accompanied with relatively small amounts of MgO and Fe2B impurities. With 5% excess Mg addition, the onset TC slightly decreased. However, the transport JC at 4.2 K and 4 T reached 1.07×104 A·cm-2, increasing by a factor of 1.4 compared to the stoichiometric sample. Moreover, the Mg1.05B2 sample showed an improved field dependence of JC, suggesting that less voids and smaller grain size of the Mg1.05B2 core lead to better grain connectivity and stronger flux pinning.展开更多
基金the Research Foundation of Science and Technology PlanProject in Liaoning Province of China (Nos.20060623 and 2006402049).
文摘An electrochemical technique has been introduced and applied to fabricate superconducting MgB2 films in molten salts. MgCl2, Mg（BO2）2, NaCl, and KCl were used as electrolyte, graphite was used as the anode, and copper was used as the cathode, respectively. X-ray diffraction （XRD） analysis was chosen to investigate the phase composition and crystallinity of the films at different electrolysis temperatures. Stan- dard four-probe technique and SQUID were applied to investigate the temperature dependence of resistance （R-T） properties and magnetic properties of the films, respectively. The results indicate that MgB2 films have been fabricated on the copper cathodes, and superconducting transition takes place close to 50 K.
基金the Beijing Municipal Science and Technology Commission (Grant No. Z07000300703)the State Key Development Program for Basic Research of China (Grant No. 2006CB601004)the National High Technology Research and Development Program for Advanced Materials of China (Grant No. 2006AA03Z203)
文摘Using commercial amorphous B powder (92% in purity) and Mg powder (99% in purity) as starting materials, 19-filament Fe/Cu clad MgB2 wires were fabricated by an in situ powder-in-tube method. Heat treatment was performed at 700℃ for 1 h under an argon gas atmosphere. The influence of Mg/B ratio on the microstructure and superconducting properties of the wires was investigated. It was found that the major phases of MgB2 wires were MgB2 accompanied with relatively small amounts of MgO and Fe2B impurities. With 5% excess Mg addition, the onset TC slightly decreased. However, the transport JC at 4.2 K and 4 T reached 1.07×104 A·cm-2, increasing by a factor of 1.4 compared to the stoichiometric sample. Moreover, the Mg1.05B2 sample showed an improved field dependence of JC, suggesting that less voids and smaller grain size of the Mg1.05B2 core lead to better grain connectivity and stronger flux pinning.
