Experimental studies of yttrium barium(2)(copper(1-x)iron(x))(3)oxygen(7+delta) and bismuth(2)strontium(2)calcium(n-1)copper(n)oxygen(2n+4) high T(c) superconductors

Fe-substituted Y123 and Bi-based high Tc superconducting samples were prepared and studied. Magnetic susceptibility measurements, x-ray diffraction and Scanning Electron Microscopy were used to study the transition temperature Tc, preferential grain orientation and phase formation of the compounds. Tc was found to decrease more rapidly with Fe concentrations above 2.5%. Thermally reducing the oxygen content shows that Fe clusters form at high Fe concentrations. Magnetic susceptibility and x-ray diffraction measurements show that only the 80 K phase is present in Bi4Sr3Ca3Cu6Ox samples. For Bi0.7Pb0.3SrCaCu1.8Ox and Bi1.8Pb0.2Sr2Ca2Cu3Ox samples, the 110 K phase becomes dominant after sintering for 126 hours and 48 hours respectively. Preferential grain orientation was also observed in these materials.