MgB2 superconductors with addition of TaB2 and SiC

L. B. S. DA SILVA; D. RODRIGUES JR.; V. C. VELLOSO METZNER; G. SERRANO; M. T. MALACHEVSKY; A SERQUIS

Águas de Lindóia

Encuentro; XXXIII Encontro Nacional de Física da Matéria Condensada; 2010

Sociedade Brasileira de Física

After the discovery of superconductivity at 39 K in MgB2, many groups around the world work to improve the current transport properties of this compound at high ¯elds (above 10T) aiming the use in magnets for particle accelerators and systems for nuclear fusion tests. On the other hand, modern magnetic resonance imaging systems work in the range 0.5 to 2.0T. In this work were developed and analyzed MgB2 samples with addition of other diboride, TaB2, and simultaneous addition of silicon carbide (SiC). The objective of the additions is to optimize the critical current densities of the material, in low and high magnetic ¯elds. The method uses the mixture of the MgB2 superconductor with the TaB2 diboride as dopant, which has the same C32 hexagonal structure as the MgB2, and SiC, that may contribute with C to replace B in the crystalline structure of the matrix. As a result of the mechani- cal mixture of the powders, obtained by ball milling, we obtained a positive in°uence in the ¯nal crystalline structure, maintaining the hexagonal structure and a good intergrain connectivity. Microstructural characterizations, performed using SEM-EDS and XRD, were extremely important to determine the distribution and composition of the superconducting phase after the addition of the TaB2 and SiC in the MgB2 matrix. Magnetic superconducting characterization using a SQUID was performed to determine the best composition of the mixture and the best heat treatment pro¯le. It could be analyzed the behavior of each dopant on the transport capacity of these materials, including the analysis of magnetic °ux pinning mechanisms.