Papers by Keyword: Ruthenocuprates

Abstract: We have synthesized Ru₁Sr₂Gd_2-xCe_xCu₂O₁₀ (Ru-1222) materials using several concentrations of Ce. All ruthenocuprate compounds have been characterised by using standard X-ray diffraction (XRD) and Scanning Electron Micrographs (SEM). The concentration of Ce affects transport properties drastically. Compounds with x=0.5 remain nonsuperconducting with moderate resistivity even after annealing in different conditions. Enormous change in the normal state resistivity has been observed in different annealing conditions of Ru-1222 with x=0.5. Superconducting properties have been observed in compounds with x=0.65. The highest critical temperature obtained is 27.5K for x=0.65. In addition, the duration of annealing in flowing oxygen is found to be effective in changing the normal state resistivity for x=0.65.

Abstract: The ruthenocuprates family is a very interesting class of materials, because of the coexistence of superconductivity and magnetic ordering. Ruthenocuprates include RuSr2RECu2O8 and RuSr2(RE,Ce)2Cu2O10- (RE = rare earth elements or Y). It is possible to synthesize samples of these phases with Gd, Eu or Sm with normal synthesis conditions. For the others high-pressure high-temperature (HPHT) synthesis is required. We had successfully synthesized the RuSr2Tb1.5Ce0.5Cu2O10 by HPHT technique, starting from RuO2, SrO2, Tb4O7, CeO2, CuO and Cu. Around 300 mg of the mixture was allowed to react in a flat-belt-typehigh- pressure apparatus at 6GPa and 1200 °C – 1550 °C. The optimised temperature of synthesis was found to be in the range between 1350 °C – 1450 °C. The as-synthesized compound crystallized with a structure belonging to the space group I4/mmm. DC magnetic susceptibility versus temperature plot for RuSr2Tb1.5Ce0.5Cu2O10 in an applied field of 10 Oe demonstrated magnetic transition at 150 K but the superconducting transition was not clearly observed. To our knowledge this is the first successful synthesis of the Tb based Ru-1222 phase.