Bulk MgxB2 superconductor production by excess Mg and hot press methods and their properties

Öz

Four different nominal compositions MgB₂, Mg_1.5B₂, Mg₂B₂ and Mg_2.5B₂ were produced by excess Mg method and hot press. These superconducting samples were compared in terms of structural, electric and magnetic properties. The superconducting phase was determined by XRD analysis, which indicated the formation of MgB₂ structure as a main matrix with some amount of non-superconducting phases, such as metallic Mg and minor amount of MgO. The electric properties of the samples were characterized by low temperature resistivity measurements under different magnetic fields 0.5, 1.0, 3.0 T. The results showed that the superconducting T_c,onset and T_c,offset transition temperatures moved to lower values. These results indicate that excess Mg method improves the superconducting and magnetic properties of MgB₂, as well as enhanced the rigidity and ductility of the samples.  Experimental results showed the advantages of the proposed methods, established the most suitable transition temperature of the samples, as well as the decline from the superconducting to normal state.  

Anahtar Kelimeler

• MgB2 superconductors,Excess Mg Method,Ring Shape,Disc Shape

Kaynakça

1. Xia Q., Yi J., Peng Y., Luo S., Li L., Microwave direct synthesis of MgB2 superconductor, Mater. Lett., 62 (24), 4006-4008, 2008.
2. Serquis A., Liao X. Z., Zhu Y. T., Coulter J. Y., Huang J. Y., Willis J. O., Peterson D. E., Mueller F. M., Moreno N. O., Thompson J. D., Nesterenko V. F., Indrakanti S. S., Influence of microstructures and crystalline defects on the superconductivity of MgB2, J. Appl. Phys., 92 (1), 351-356, 2002.
3. Yanmaz E., B. Şavaşkan B., Başoğlu M., Koparan E.T., Dilley N., Grovenor C., Complete flux jumping in nano-structured MgB2 superconductors prepared by mechanical alloying, J. Alloys Compd., 480 (2), 203-207, 2009.
4. Radev D., Marinov M., Tumbalev V., Radev I., Konstantinov L., Mechanically activated self-propagated high-temperature synthesis of nanometer-structured MgB2, Physica C, 418 (1), 53-58, 2005.
5. Schmidt J., Schnelle W., Grin Y., Kniep R., Pulse plasma synthesis and chemical bonding in magnesium diboride, Solid State Sci., 5 (4), 535-539, 2003.
6. Savaskan B., Ozturk K., Celik S., Yanmaz E., Improvement of superconducting properties of MgB2 by changing the argon ambient pressure and sintering conditions, J. Phys. Conf. Ser., 2009.
7. Babaoğlu M.G., Safran S., Çiçek Ö., Ağıl H., Ertekin E., Hossain M. S. A., Yanmaz E., Gencer A., Microstructural and superconducting properties of C 6H6 added bulk MgB2 superconductor, J. Magn. Magn. Mater., 324 (21), 3455-3459 2012.
8. Sinha B., Kadam M., Mudgel M., Awana V., Kishan H., Pawar S., Synthesis and characterization of excess magnesium MgB2 superconductor under inert carbon environment, Physica C, 470 (1), 25-30, 2010.

9. Giunchi G., Ceresara S., Ripamonti G., Di Zenobio A., Rossi S., Chiarelli S., Spadoni M., Wesche R., Bruzzone P., High performance new MgB2 superconducting hollow wires, Supercond. Sci. Technol., 16 (2), 285, 2003.
10. Yanmaz E., Ozturk K., Dancer C., Basoglu M., Celik S., Grovenor C., Levitation force at different temperatures and superconducting properties of nano-structured MgB2 superconductors, J. Alloys Compd., 492 (1), 48-51, 2010.