Structural refinement of [Y1-xCax]SrBaCu2.80(PO4)0.20Oy

Abstract [Y 1− x Ca x ]SrBaCu 2.80 (PO 4 ) 0.20 O y samples with 0.10⩽ x ⩽0.40 were synthesized using the solid state reaction technique. X-ray diffraction patterns show that all the compounds crystallized into a 123 tetragonal structure. The analyses of the structure with Rietveld refinement were made using a model that contain one Cu(2) in a four coordination and not in five coordination as the other 123 tetragonal structures. This fact permits that the T c increases with Ca concentration. All samples are superconductors as reported previously.