相关论文: Magnetic shielding in MgB2/Fe superconducting wire…
Transport critical current (Ic) was measured for Fe-sheathed MgB2 round wires. A critical current density of 5.3 x 10^4 A/cm^2 was obtained at 32K. Strong magnetic shielding by the iron sheath was observed, resulting in a decrease in Ic by…
Magnesium diboride superconducting wires give the largest critical current density (Jc) when produced with iron sheath. Because iron is ferromagnetic, it is expected to improve the field dependence of Jc by shielding of the external field…
Local magneto-optical imaging and global magnetization measurement techniques were used in order to visualize shielding effects in the superconducting core of MgB_2 wires sheathed by ferromagnetic iron (Fe). The magnetic shielding can…
Interaction between the superconductor and ferromagnet in MgB2/Fe wires results in either a plateau or a peak effect in the field dependence of transport critical current, Ic(H). This is in addition to magnetic shielding of external field.…
The nano-SiC doped MgB2/Fe wires were fabricated using a powder-in-tube method and an in-situ reaction process. The depression of Tc with increasing SiC doping level remained rather small due to the counterbalanced effect of Si and C…
Doping of MgB2 by nano-SiC and its potential for improvement of flux pinning was studied for MgB2-x(SiC)x/2 with x = 0, 0.2 and 0.3 and a 10wt% nano-SiC doped MgB2 samples. Co-substitution of B by Si and C counterbalanced the effects of…
Magnetic measurements carried out on MgB_2 superconducting round wires have shown that the critical current density J_c(B_a) in wires sheathed by iron can be significantly higher than that in the same bare (unsheathed) wires over a wide…
We have fabricated a series of ex situ copper sheathed powder-in-tube MgB2 wires with 20% by volume Ag, Pb, In, and Ga metal added to the MgB2 powder. We find the transport critical current of these wires increases significantly with the…
We report magnetic field dependent magnetization and microwave impedance measurements on a MgB2 superconductor prepared by high pressure synthesis. We find that the upper critical field is linearly dependent on temperature near Tc and the…
We investigated the effect of SiC nano-particle doping on the crystal lattice structure, critical temperature T_c, critical current density J_c, and flux pinning in MgB_2 superconductor. A series of MgB_{2-x}(SiC)_{x/2} samples with x = 0…
A comparative study of pure, SiC, and C doped MgB2 wires has revealed that the SiC doping allowed C substitution and MgB2 formation to take place simultaneously at low temperatures. C substitution enhances Hc2, while the defects, small…
Monofilamentary MgB2-wires with a 2- or 3-component sheath containing mechanical reinforcing stainless steel (SS) were prepared and characterized. In direct contact to the superconductor Nb, Ta or Fe was used. For a selection of samples…
We have studied the vortex-matter phase diagram of low C doped MgB$_2$ superconductor. The significant finding is the appearance of a peak effect, which, as both our global magnetization and local ac susceptibility measurements revealed, is…
Monofilamentary MgB2-wires with a mechanical tough Nb/Cu/steel or Fe/steel sheath were prepared and characterized. The steel content was varied to investigate the reinforcement effect and the consequences for the superconducting properties…
Superconducting MgB2 strands with nanometer-scale SiC additions have been investigated systematically using transport and magnetic measurements. A comparative study of MgB2 strands with different nano-SiC addition levels has shown…
We report on transport and magnetization measurements of the critical current density Jc in ErNi2B2C single crystals that show strongly enhanced vortex pinning at the Neel temperature TN and low applied fields. The height of the observed Jc…
An improvement of the transport critical current density, Jc, of MgB2 wires was obtained after addition of 10 wt.% B4C powders, after reaction at 800 C: Jc values of 1.10^4 A/cm2 at 4.2 K and 9T were obtained for wires of 1.11 mm diameter…
The upper critical field, $H_{c2}$, of Mg(B$_{1-x}$C$_x$)$_2$ has been measured in order to probe the maximum magnetic field range for superconductivity that can be attained by C doping. Carbon doped boron filaments are prepared by CVD…
We report the synthesis and characterization of graphite (C) doped MgB2-xCx (x = 0.0, 0.1, 0.2 and 0.3) samples. The crystal structure and microstructural characterization have been investigated by x-ray diffractometer and transmission…
The critical current density (Jc) of hot isostatic pressed (HIPed) MgB2 wires, measured by d.c. transport and magnetization, is compared with that of similar wires annealed at ambient pressure. The HIPed wires have a higher Jc than the…