In the fully oxygenated single phase (La1−x−uPrxCau)(Ba1.5Sr0.5)Cu3Oy (0≤x≤1.00, 0≤u≤0.20) system, if u=0, the z-coordinate of the Ba site, z(Ba), and dBa–bp (distance between the Ba site and the basal plane) are lowered by increasing the amount of Pr in the (La1−xPrx)(Ba1.5Sr0.5)Cu3Oy series. On the contrary, if u≠0, z(Ba) and dBa–bp are raised by increasing the amount of Ca ion in the (La1−x−uPrxCau)(Ba1.5Sr0.5)Cu3Oy (0≤x≤0.30, 0≤u≤0.20) series. Linear relationships are found between z(Ba), dBa–bp and the oxygen stoichiometry (y). Tc and psh (the hole concentration in CuO2 layers) increase with increasing the angle of Cu(2)-Ba-Cu(2). Relative positions of the Cu(2) and Ba sites are important in determining the Tc of these 123 compounds.
Journal of low temperature physics 131(3-4), pp.719-724