Crystallographic analysis and conductivity fluctuations of the Y2Ba5Cu8O17 superconductor

Abstract

Synthesis of the Y 2 Ba 5 Cu 8 O 17 superconducting material by the standard solid state reaction is reported. DC resistivity measurements reveal a bulk Tc = 104.95 K which was determined by the criterion of the maximum in the numerical temperature derivative of electrical resistivity. Structure characterization was performed by means of the X-ray diffraction (XRD) technique. A Rietveld refinement of XRD patterns shows that the material crystallizes in an orthorhombic structure, space group Pmm2 with cell parameters a = 3.8712(0) Å, b = 3.8481(4) Å and c = 27.1601(4) Å. In order to study the pairing mechanism close to Tc, conductivity fluctuation analysis was performed by the method of logarithmic temperature derivative of the conductivity excess. Close and above Tc, the conductivity fluctuation analysis reveal the occurrence of two fluctuation regimes characterized by the critical exponents λ 3D = 0.52 and λ 1D = 1.51, corresponding to 3D and 1D Gaussian regimes, respectively. The correlations of the critical exponents with the dimensionality of the fluctuation system for each Gaussian regime were performed by using the Aslamazov–Larkin theory.