Faculté des sciences

The effect of carbon and rare earth oxide co-doping on the structural and superconducting properties of MgB₂

Ojha, N. ; Malik, Vivek Kumar ; Singla, Rashmi ; Bernhard, Christian ; Varma, G. D.

In: Superconductor Science and Technology, 2010, vol. 23, no. 4, p. 045005

Carbon (C) and rare earth oxide (REO) co-doped bulk polycrystalline MgB₂ samples with nominal compositions Mg1 − y(REO)y(B0.95C0.05)₂ (where y = 0.00, 0.01, 0.03, 0.05 and REO = Eu₂O₃ or Pr₆O₁₁) have been synthesized via a solid state reaction route. The XRD results reveal the presence of impurity phases EuB₆ in... Plus

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    Summary
    Carbon (C) and rare earth oxide (REO) co-doped bulk polycrystalline MgB₂ samples with nominal compositions Mg1 − y(REO)y(B0.95C0.05)₂ (where y = 0.00, 0.01, 0.03, 0.05 and REO = Eu₂O₃ or Pr₆O₁₁) have been synthesized via a solid state reaction route. The XRD results reveal the presence of impurity phases EuB₆ in Eu₂O₃ and PrB₄ and PrB₆ in Pr₆O₁₁ co-doped samples along with the main hexagonal phase of MgB₂ and a small amount of MgO. The values of upper critical field (Hc2) and irreversibility field (Hirr), except Hc2 of y = 0.05 for Eu₂O₃, have been found to increase at all temperatures (<Tc) with increasing doping concentration of REO. Improvements in the values of critical current density (Jc) at 10 K for y = 0.01 of Eu₂O₃ and y = 0.01, 0.03 of Pr₆O₁₁ co-doped samples have been observed in high fields (>6.5 T) region. At 20 K enhancement in the high field (>6 T)  Jc values for y = 0.01, 0.03 of Eu₂O₃ and y = 0.01 of Pr₆O₁₁ co-doped samples are also reported in the present work. The correlations between the structural characteristics and the observed superconducting properties of the co-doped samples are described and discussed in this paper.