The LaCaBaCu2.80(X)0.20(O)7-δ compound with X=(P04)^(3-) and (BO3)^(3-) has been prepared by a solid state reaction method and we compare the resulting structures. phase formation and CriticaL Temperatures (Tc's) with the well known LaCaBaCu3(O)7-δ (La1113) superconductor. For both cases, the X-ray diffractogram revealed the BaCuO2 and CuO as extra phases; this is confirmed by SEM, EDX and HAEM. The Rietveld analysis suggested orthorhombic crystalline structures belonging to the Pmmm spatial group with a=3.849Å, b=3.880Å and c=11.630Å to the LaCaBaCu2.80(P04)0.20(O)7-δ, and a=3.884Å b=3.890Å and C=11.640Å to the LaCaBaCu2.80(BO3)0.20(O)7-δ. Tc's were calculated from the derivativa of magnetic susceptibility plots by using a SQUID detection system, these indicated the Tc's are 86K and 55K to the LaCaBaCu2.80(P04)0.20(O)7-δ and the LaCaBaCu2.80(BO3)0.20(O)7-δ respectively.

The LaCaBaCu2.80(X)0.20(O)7-δ compound with X=(P04)^(3-) and (BO3)^(3-) has been prepared by a solid state reaction method and we compare the resulting structures. phase formation and CriticaL Temperatures (Tc's) with the well known LaCaBaCu3(O)7-δ (La1113) superconductor. For both cases, the X-ray diffractogram revealed the BaCuO2 and CuO as extra phases; this is confirmed by SEM, EDX and HAEM. The Rietveld analysis suggested orthorhombic crystalline structures belonging to the Pmmm spatial group with a=3.849Å, b=3.880Å and c=11.630Å to the LaCaBaCu2.80(P04)0.20(O)7-δ, and a=3.884Å b=3.890Å and C=11.640Å to the LaCaBaCu2.80(BO3)0.20(O)7-δ. Tc's were calculated from the derivativa of magnetic susceptibility plots by using a SQUID detection system, these indicated the Tc's are 86K and 55K to the LaCaBaCu2.80(P04)0.20(O)7-δ and the LaCaBaCu2.80(BO3)0.20(O)7-δ respectively.

It is known the YBa2Cu30H (Yl23) prepared by the solid reaction method coexists with a green phase Y2BaCu05 (Y211). In this work we study the behavior of the Y211 (pure) overheated at 11 00°C and 1300°C respectively. The starting sample was prepared by the conventional solid reaction method using appropriate amounts of Y203, BaC03 and CuO; the initial sample was green in color. From the X ray diffractogram (XRD) and using the Rietveld refinement we found that the crystalline structure is orthorhombic and belong to the Pnma spatial group. This is the sorne structure as the one found by Michael and Raveau 1 • The starting sample was overheated at 11 00°C under oxygen pressure of 0.1 atm. According with the XRD, there are no significant variations on its structure. Nevertheless after an overheating of 1300°C in the same oxygen pressure, a new phase Y203 with a cubic symmetry together ...