Synthesis of ruthenium-based layered cuprates in ammonium nitrate melt and their characterisation

Synthesis in the ammonium nitrate melt was used to obtain polycrystalline samples of complex copper-ruthenium oxides RuSr(2)Ln(1+x)Ce(1-x)Cu(2)O(10-y) (Ru-1222) and RuSr(2)LnCu(2)O(8) (Ru-1212) (Ln = Sm, Gd and Eu), as well as Ru(1-x)A(x)Sr(2)GdCu(2)O(8) (A = Pd, Os, Rh; x = 0.2, 0.4). Magnetic and superconducting properties of these samples were studied. The superconducting transition temperature in the RuSr(2)Ln(1.5)Ce(0.5)Cu(2)O(10-y) compound was found to be higher compared with the samples obtained using the solid state synthesis. At the same time, the new synthesis process has a much shorter duration. RuSr2GdCu2O8 compound is also produced faster in the ammonium nitrate melt. Doping with Os, Rh, Pd expedites the development of superconductivity in these samples. (C) 2002 Elsevier Science B.V. All rights reserved.