Ghazala Y. Hermiz
Samples of Mg-doped bismuth 2223 superconducting materials with nominal composition Bi1.6Pb0.4Sr2Ca2- xMgxCu3O10+δ (0≤ x ≤0.5) were synthesized by solid-state reaction method .The effect of magnesium on structural ,electrical resistivity and dielectric properties [dielectric constants (real and imaginary part ), dielectric loss factor (tan δ) and ac-conductivity (ζ ac) as a function of frequency ] has been investigated . XRD analysis showed the system has an orthorhombic structure with c/a ratio for Bi1.6Pb0.4 Sr2Ca1.8Mg0.2Cu3O10+δ system more than the other samples. A sharp drop of resistivity was observed for the same sample with a transition temperature equal to 104 K. The negative value of capacitance at lower frequencies for samples with x=0, 0.2, 0.5 has been observed in the dielectric measurements of these samples. This may attributed to difference in the Fermi levels of the contact electrodes with the superconductor ceramic sample.
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