We report the phase formation and superconductivity in [Y1-xCax]SrBaCu2.80(BO3) 0.20Oy with 0.10≤ x ≤ 0.50 prepared at normal pressure and temperature. The X-ray diffraction pattern shows that all samples have a tetragonal P4/mmm structure, indicating that the BO3 groups were incorporated in the structure. The ZFC magnetization versus temperature measurements under an applied field of 10 Oe using a SQUID magnetometer, show that the materials are superconductors, with Tc ≈ 77K, almost independently of the Ca content. The observed differences are related to the volume fraction of Meissner effect. In the temperature range 100-300K all samples show a typical Curie - Weiss behavior, under an applied high field of 20 KOe.
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* This work was supported by the Superior Council of Research (SCR) of the UNMSM under contract # 91301031