Granular superconductivity in polycrystalline Bi2Sr2CaCu2O8+δ by homovalent La substitution on Bi sites

Effect of Er/Y addition on the growth and superconductivity of Bi2212 films

“…As the external magnetic field increased, resulting in an increasing normal-state core region, a decreasing superconducting fraction, a decreasing T c,zero with increasing magnetic field and an increasing Δ T c value. 43 The irreversibility field ( H irr ) of the Er2 sample was fitted by eqn (3) and the results were shown in Fig. 6(c). H irr ∝ (1 − T / T c ) β where T was the critical temperature value under the external magnetic field and T c was the critical temperature value under the self-field.…”

Crystalline characteristics and superconducting properties of Bi2212 thin films prepared by the Pechini sol–gel method: the effect of different substrates on the film growth

“…The T c,onset and T c,zero valves of the optimal sample M1 are 91.26 and 60.12 K, respectively. The superconducting behaviour of sample M4 is due to the effect of a grain boundary with about 2 residual resistance (Li et al, 2010). Meanwhile, the excellent superconducting properties of group L are shown in Fig.…”

Detailed analysis on electrical conduction transition from 2D variable range hopping to phonon-assisted 3D VRH mechanism belonging to Bi-site La substituted Bi-2212 system

“…where ) (T ρ called as total resistivity shows the specimen resistivity at any temperature and ) (T i ρ denotes the ideal resistivity (temperature-dependent) when temperature-independent res ρ presents the residual resistivity (arising from the defect interfaces such as grain boundaries, stacking faults, voids, planar and micro defects) of the materials [30][31][32]. One can easily observe from Fig.1 that the temperature-independent resistivity tends to increase rapidly.…”

“…This phenomenon relies on the fact that partial substitutions of Bi 3+ ions with smaller ionic radius (1.03 Å< 1.18 Å) by La 3+ ions forming the local structural distortions make the offset c T values degrademonotonously[59]. On the other hand, no dramatic change in the onset c T values with the partial substitution of homovalent La on Bi sites points out stability of the oxygen concentration in the crystal planes[32]. As for the doping value of x=0.20, characteristic two different transition (low-T c phase and very low-T c phase)regions are obviously observed in the superconducting state due to not only the beginning of the major disorders (enhancement of the porosity and weak links between the grains) in the crystal structure but also the rapid decrement in the mobile hole concentration and average crystallite size[60,61].…”