Original Paper

Journal of Superconductivity and Novel Magnetism

, Volume 25, Issue 1, pp 45-53

First online:

Effect of MgO Nano-oxide Additions on the Superconductivity and Dielectric Properties of Cu0.25Tl0.75Ba2Ca3Cu4O12−δ Superconducting Phase

  • N. H. MohammedAffiliated withPhysics Department, Faculty of Science, Alexandria University Email author 

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The effect of MgO nano-oxide on both superconducting and dielectric properties of polycrystalline (Cu0.25Tl0.75)-1234 was studied. The MgO-content varied from x=0.0 up to 1.0 wt% of the sample’s total mass. The volume fraction of the prepared samples (x=0.0, 0.2, 0.6 and 1.0 wt%) was estimated from the room-temperature X-ray powder diffraction patterns. The superconducting transition temperature T c, calculated from resistivity data, increased from 122 to 136 K as x increased from 0.0 to 0.8 wt% and then it decreased to 117 K for x=1.0 wt%. Also, the dielectric properties of all samples were measured in the frequency range from 100 Hz to 4 MHz at different temperatures from 113 to 300 K. The real part of dielectric constant ε′ was strongly dependent on both temperature and frequency for all x values. The imaginary part of dielectric constant ε″ and loss factor tan δ showed dispersion which shift toward lower frequencies with decreasing temperature. The ac conductivity σ ac was derived from the admittance and sample dimensions in the same frequency range. It followed the power law σ ac(ω)∼ω γ with γ≈0.8.


(Cu,Tl)-1234 MgO nano-particles Dielectric constants Loss factor