Solid solutions (Ru,Nb)Sr2(Sm1.4Ce0.6)Cu2O10−δ: Synthesis, structure, and properties

Solid solutions of as-batch composition (Ru1−xNbx)Sr2(Sm1.4Ce0.6)Cu2O10−δ (the Ru,Nb)-1222 phase), where x = 0.0, 0.25, 0.50, 0.75, or 1.00, have been synthesized and characterized by X-ray diffraction. A correlation is proposed between the refined composition of the Ru-1222 and Nb-1222 phases and their structural features. With increasing oxygen concentration in the Ru-1222 phase, the superconducting transition temperature increases from Tc = 28 to Tc = 34 K. The composition and magnetic properties of the Ru-1222 phase are affected by the batch composition: unlike in Ru + RuO2 mixtures, the presence of ruthenium in the batch decreases the oxygen proportion and increases the magnetic ordering temperature Tm; the phase of as-batch composition NbSr2(Sm1.4Ce0.6)Cu2O10−δ is paramagnetic.