Publications

Superconducting samples of type Y3Ba5Cu8O18−δY3Ba5Cu8O18−δ substituted by both Nd3+Nd3+ and Ca2+Ca2+ ions were prepared by a solid-state reaction technique. These substitutions affect the phase formation, lattice parameters, grains formations and superconducting transition temperature TcTc. The change in these parameters is mainly due to the partial substitution of Ba2+Ba2+ by Ca2+Ca2+ ions rather than the partial substitution of Y3+Y3+ by Nd3+Nd3+ ions. The analysis of the electrical resistivity ρ(T)ρ(T) versus temperature above TcTc was carried out using Aslamazov–Larkin (AL) and Lawrence–Doniach (LD) models. Different fluctuation regions starting from high temperature up to TcTc were estimated, and denoted by short-wave (sw), two-dimensional (2D), three-dimensional (3D) and critical (cr) fluctuations. A distinct crossover temperature (T2D−3D=TLDT2D−3D=TLD) from 2D to 3D, in the Mean Field Region (MFR), is shifted to lower temperature by increasing substitutions content. The superconducting parameters such as zero temperature coherence length along the cc-axis ξc(0)ξc(0), inter-layer coupling strength νν, Fermi Velocity VFVF of the carriers and Fermi Energy EFEF were calculated as a function of substitution content.