INVESTIGADORES
SERQUIS Adriana Cristina
congresos y reuniones científicas
Título:
Effects of doping on the superconductivity of MgB2
Autor/es:
A SERQUIS
Lugar:
Rio de Janeiro
Reunión:
Conferencia; Avanços e Perspectivas da Ciência no Brasil, América Latina e Caribe; 2007
Institución organizadora:
Brazilian Academy of Sciences - TWAS
Resumen:
The strong potential for commercial applications of MgB2 is due to a unique combination of characteristics, such as a high transition temperature Tc~39K, chemical simplicity, lightweight and low cost of the raw materials. In addition, the absence of weak-link behavior at grain boundaries in polycrystalline samples allows the use of simple Powder In Tube (PIT) methods to fabricate wires and tapes. One of the most important issues for MgB2 magnet applications is the simultaneous enhancement of its critical current density (Jc) and the upper critical field (Hc2). Thus, on one hand, the pinning force may be improved by the incorporation of defects (nano particle doping, chemical substitutions, etc.). On the other hand, the doping level affects the intraband scattering coefficients and the diffusivity of the two bands of this peculiar superconductor, and these changes may cause a significant Hc2 variation…       Here I will first present a review of different kind of doping and substitutions in the superconducting properties of MgB2 bulk samples. In particular, we analyze the correlated enhancement of Hc2 and critical current densities Jc obtained by SiC, single (SW) or double (DW) wall carbon nanotubes (CNT) doping, to understand the role of C substitution and other defects in MgB2 superconducting properties… …In second place I will describe our recent progress in the processing, microstructures and superconducting properties of MgB2 conductors prepared by PIT. Several sheath materials (stainless steel, copper and titanium) are used to fabricate SiC and carbon nanotubes (CNT) doped MgB2 wires and tapes The microstructure and phase composition of the conductors are followed during the deformation and heat treatment processes by Scanning Electron Microscopy (SEM) and X-Ray Diffractometry (XRD). Critical temperatures (Tc), Jc and Hc2 are determined by magnetization and transport measurements. The correlation between the superconducting properties and the microstructural characteristics is discussed.