Effect of Rubidium Substitution on the Physical and Superconducting Properties of Textured High-Tc BSCCO Samples

In this research, the effects of rubidium (Rb) substitution on the microstructural, physical, and superconducting properties of Bi₂Sr₂Ca_1-xRb_xCu₂O_{8 + y} with x = 0.0, 0.025, 0.05, 0.075, 0.10, and 0.125 superconductor have, in detail, been studied. For this purpose, samples were prepared through the classical solid state reaction route, followed by directional grown using the laser floating zone technique and annealing. XRD measurements showed that all samples are composed of Bi-2212 phase as the dominant one, together with less amount of secondary phases. The crystal symmetries of samples were determined as pseudo tetragonal. SEM-EDX confirmed that Bi-2212 phase is the major one, with minor amounts of Bi_{2 + x}(Sr,Ca)₂O_{6 + d}, (Sr,Ca)CuO₂, CuO₂, and CaO secondary phases. In magnetization versus temperature measurements, very sharp diamagnetic transition is observed. The critical onset temperatures, T_C, for all samples are obtained around 90 K. From M-H measurement, it has been found that all samples have very large loop areas. By using the data from M-H measurements in the Bean model, the intragranular critical field, J_C, has been determined. It has been found that the x = 0.05Rb sample shows the highest superconducting properties and the largest J_C values (2.2 10⁵ A/cm² at 10 K). Moreover, the maximum pinning force, F_Pmax, at this temperature has also been obtained in x = 0.05Rb sample (8.5 10⁸ Oe A/cm²).