SCOPF analysis of YBa2Cu3O7−δ+xCr2O3 superconductor composite

Abstract

A series of YBa2Cu3O7−δ+xCr2O3 (x=0.0, 2.3, 4.4, and 6.1wt%) samples were prepared using solid state reaction method. Microstructural analysis reveal the reduced grain size with the incorporation of magnetic Cr2O3 particles in the YBCO matrix. XRD graphs show the unchanged orthorhombic structure and improved oxygen ordering in the composite samples. With the increase of Cr2O3 wt%, it is found that the superconducting transition temperatures determined from standard four-probe method decreases gradually. Excess conductivity fluctuation analysis using Aslamazov–Larkin model fitting reveals transition of two dominant regions (2D and 3D) above Tc. 2D to 3D crossover temperature i.e. Lawerence–Doniach temperature that demarcates dimensional nature of fluctuation inside the grains is influenced by Cr2O3 incorporation in YBCO matrix. The decrease in Lawerence–Doniach temperature in the mean field region has been observed as a consequent dominance of 3D region with increase in wt% of Cr2O3 in the composite. The decrease in zero-resistance critical temperature and increase in transition width signifies the degradation of intergrain weak links.