Influence of the starting composition on the structural and superconducting properties of MgB2 phase

الأصل · EN

We report the preparation of Mg₁₋ₓB₂ (0≤0.5) compounds with the nominal compositions. Single phase MgB₂ was obtained for x=0 sample. For 0<x≤0.5, MgB₄ coexists with "MgB₂" and the amount of MgB₄ increases with x. With the increase of x, the lattice parameter c of "MgB₂" increases and the lattice parameter a decreases, correspondingly Tc of Mg₁₋ₓB₂ decreases. The results were discussed in terms of the presence of Mg vacancies or B interstitials in the MgB₂ structure. This work is helpful to the understanding of the MgB₂ films with different Tc, as well as the Mg site doping effect for MgB₂.