Synthesis and Characterization of (CaxLa1-x)(Ba1.75-xLa0.25+x)Cu3O7+δ Tetragonal Superconductor by an Aqueous Solution Technique Using Citric Acid

Polycrystalline samples of (CaxLa1-x)(Ba1.75-xLa0.25+x)Cu3O7+δ tetragonal superconductor for Ca content(x)from 0.0 to 0.6 were synthesized by a simple aqueous solution technique using citric acid. The combined results of X-ray diffraction and Raman scattering analysis indicated that the polycrystalline samples for the entire Ca content (x) were of single-phase character. The Tc onset values for (x) from 0.0 to 0.6, determined precisely from the complex magnetic susceptibility measurements, increased from 45.0 K for x=0.0 to 78.7 K for x = 0.4, remained almost constant at 80 K between x=0.5 and x=0.6. It was also found that sintering condition affected rather dramatically superconducting properties in this system.