Effect of oxygen redistribution in Bi-based high-Tc superconductors on their normal and superconducting properties

Electrical transport effects due to oxygen content modifications in a Bi2Sr2CaCu2O8+δsuperconducting whisker

“…For instance, Gurvitch and Fiory [30,31] showed that the resistivity curve of YBa 2 Cu 3 O 7 (YBCO) bulk samples deviated from linearity for T > 600 K, ascribing this effect to the oxygen loss from the material. Moreover, in a more recent paper Romanenko et al [32] reported the same upturn for Bi-2212 superconductor at T ≈ 400-500 K. In this case this behaviour was interpreted as being due to both an oxygen reordering and an oxygen partial removal from the samples, which were induced by the very slow heating rate (2 K h −1 ) of the experiment.…”

Electrical study of an unusual phase transformation in a Bi2Sr2Ca2Cu3O10+xwhisker at room temperature

“…On the other hand, Kumar et al [10] emphasized in a recent paper that annealing a single crystal at 200 • C for 5 min in high-purity gas atmospheres could induce significant changes in the transition temperatures and in the oxygen content. Moreover, Romanenko et al [54] showed how a slow (∼2 K h −1 ) heating of Bi-2212 samples led to a redistribution of oxygen atoms already at temperatures below 400 K and could be accompanied by a partial removal of oxygen. The importance of these phenomena is probably enhanced in samples of microscopic sizes, where the diffusion of the Cu ions along the b-axis is very likely associated with the oxygen diffusion along the same direction [13].…”