Ca doped YBCO on the Ba site

The effect of partial, nominal replacement of Ba with Ca on the properties of the YBa₂Cu₃O_6+gd superconductor varies with the concentration of Ca. For nominal concentrations in Ca up to 50% a two phase system is formed: the known superconducting phase Y_1–yCa_yBa₂Cu₃O₆₊ and a new, non superconducting phase of composition Y_1.14Ca_1.58Cu_3.27O_6.45. The x-ray diffraction pattern of this new phase matches the Bragg peaks, as well as the commensurate and incommensurate peaks of a partially indexed pattern of the phase Y_2–xCa_2+xCu₅O₁₀. For nominal Ca concentrations 40 and 50%, microprobe analysis shows that the superconducting phase becomes a mixture of Y_1–yCa_yBa₂Cu₃O_6+° and YBa_1.8Ca_0.2Cu₃O_6.5, where Ca enters the structure in the Ba site. The microraman spectra indicate a small substitution of Ba by Ca, while the new phase shows novel characteristics.