Superconductivity in the system [Y_0.8Ca_0.2](SrBa) Cu_3-x(BO₃)_xO_7-δ with 0.1≤x≤0.5

We present X-ray diffraction and magnetization measurements of the compound [Y_0.8Ca_0.2]SrBaCu_3-x(BO₃) _xO_7-δ with 0.1≤x≤0.5. Samples were prepared by the solid state reaction method under normal conditions of pressure and temperature, and replacing amounts of borate (BO₃)^3- in the Cu(1) site of [Y_0.8Ca_0.2]SrBaCu₃O _7-δ. The X-ray diffraction patterns reveal a monophasic compound. Rietveld refinements were done with the consideration of an orthorhombic crystalline model, belonging to Pmmm spatial group for most the samples; nevertheless there are significant variations in the cell's parameters. We propose the crystalline structure for the [Y_0.8Ca _0.2]SrBaCu_3-x(BO₃)_xO _7-δ with the indication of the borate occupying the Cu(1) site. The T_C were determinate by the measurements of magnetization versus temperature using a SQUID detection system, which indicates the T_C vary according with the concentration of borate. For instance to x=0.10; 0.30 and 0.50, the T_C's are 35, 38 and 28 K, respectively.