Bi2(Sr, Ln)2CuOz (Ln = Nd, Sm) phases: stability, crystal growth and superconducting properties

Bi₂(Sr,Ln)₂CuO_z (Ln = Nd, Sm) single crystals were successfully grown by a self-flux method from stoichiometric and (Bi, Cu)-rich melts. Thermal analysis and thermogravimetry were used to determine stability and the melting sequence of Bi₂(Sr,Ln)₂CuO_z phases in air. As-grown crystals of the ideal Bi₂(Sr,Ln)₂CuO_z phase, of dimensions 1×0.5×0.03 mm³, exhibit superconducting behaviour with critical temperature T_c = 21 K for the Bi_1.9Sr_1.6Nd_0.6CuO_z crystal and T_c = 14 K for the Bi_1.8Sr_1.6Sm_0.6CuO_z crystal. The compositions of these crystals were homogeneous and close to the stoichiometric composition. We report on the growth of Bi₂Sr_2-xSm_xCuO_z single crystals of large dimensions 9×3×0.03 mm³ using Bi₂Sr_1.5Sm_0.5CuO_z as precursor and Bi₂CuO₄ as flux.