Crystal Structure and Characterization of Pure and Ag‐Doped (La_1−xY_x)₂Ba₂CaCu₅O_z (0≤x≤0.5) Superconductors

Abstract

Pure and 5 wt% of Ag‐doped (La1−xYx)2Ba2CaCu5Oz superconducting compounds for x=0–0.5 have been prepared. Analysis of X‐ray diffraction patterns shows that the samples are essentially in the single‐phase form and they could be refined using the P4/mmm space group in a tetragonal cell. The typical lattice parameters are found to be a=b=3.879 Å, c=11.646 Å for x=0 and a=b=3.856 Å, c=11.576 Å for x=0.5 samples. The detailed crystal structure parameters are presented. The average grain size values from scanning electron microscope images are found to be in the order of 1–3 μm. Temperature variations of ac susceptibility and electrical resistivity have been measured. Superconducting transitions with diamagnetic Tc ranging from 60 to 75 K have been observed, with the maximum Tc for the x=0.25 sample. Ag‐doped samples exhibit improved inter‐granular coupling and homogeneous oxygenation.