The superconducting properties of single phase La1·5−xCax+yBa1·5−yCu3Oz, 0·0≤x≤0·60 (LC) and 0·0≤y≤0·70 (CB), compounds with tetragonal triple-perovskite structure are studied, using X-ray diffraction for their resistivity, a.c. susceptibility, and oxygen-content. La1·5−xCaxBa1·5Cu3Oz (LC) samples, 0·15≤x≤0·60, are superconducting withTcR=0 between 40 and 74 K. With the increase inx, the oxygen content, hole concentration in the CuO2 layers as well as theTc increase. It is interesting to find that although the hole concentration and oxygen stoichiometry of the LaCa0·5+yBa1·5−yCu3Oz (CB) compounds increase with the increase iny, theTcR=0 remains nearly constant around 74 K fory=0·0−0·70. A correlation exists between theTc and the hole concentration for LC and CB compounds.
Volume 43, 2020
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