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

Abstract

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.  

Keywords

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

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