Structural and Electric Properties of the Ru0.9M0.1Sr2GdCu2O8 System with M = Zr, Mo, and Mn

The superconducting properties of the RuSr2GdCu2O8 ceramic system depend strongly on the synthesis conditions and the ionic substitutions. In this work, we studied the structural and electrical properties of the Ru0.9M0.1Sr2GdCu2O8 system, with M = Zr, Mo, and Mn. The samples were prepared by solid-state reaction at ambient pressure in air, using temperatures between 980 °C and 1020 °C. X-ray powder diffraction patterns indicate that all samples crystallize in a tetragonal symmetry (S.G. P4/mmm, No. 123). The structural data of each sample was refined by the Rietveld method, showing that the Cu-O (1) and Ru-O (1) bond lengths vary with the substituted ionic radii of Zr, Mo, and Mn ions. Electrical resistance measurements indicate that the samples annealed in flowing oxygen at 1050 °C and 1055 °C for 5 days exhibit a semiconductor like behavior for M = Mo and Mn, whereas the samples with M = Zr and Ru show superconducting behavior.