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

Abstract

In this research, the effects of rubidium (Rb) substitution on the microstructural, physical, and superconducting properties of Bi 2 Sr 2 Ca 1-x Rb x Cu 2 O 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) 2 O 6+d , (Sr,Ca)CuO 2 , CuO 2 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 Beanmodel, 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 10 5 A/cm 2 at 10 K).Moreover, the maximum pinning force, F Pmax , at this temperature has also been obtained in x = 0.05Rb sample (8.5 10 8 Oe A/cm 2 ).

Laser Floating Zone Growth: Overview, Singular Materials, Broad Applications, and Future Perspectives

“…Due to the higher stability of the Bi-2212 phase, an important amount of work reported was focused on this phase [132,135,164,168,[173][174][175][176][177][178][179][180][181][182][183]. During these works, the Nd:YAG radiation started to be used as an alternative to the CO 2 lasers [168,175], observing that, with similar focusing optics, 1.06-µm radiation is more adequate to process textured Bi-2212 superconductors because these oxides absorb the 10.6-µm radiation mostly in the surface, creating larger radial temperature gradients and larger radial inhomogeneities due to constitutional supercooling.…”

“…Also, the substitution of some cations has been explored. For instance, Ca substitution by Y ions [181] generates an increase in the critical temperature values but with a deterioration of the grain alignment, while substitution by Rb [182] or Cs [183] leads to an increase of the pinning force at 10 K by about 20%.…”

“…High-temperature superconducting ceramics have been among the most commonly studied materials with LFZ [29,122,125,133,[160][161][162][164][165][166][167][168][169][170][171][172][173][174][175][176][177][178][179][180][181][182], probably because their anisotropic structure is ideal for directional solidification processing. As reviewed above, LFZ has demonstrated excellent microstructural transformations that result in high critical current elements in rod and tube geometries.…”