Electrical study of an unusual phase transformation in a Bi₂Sr₂Ca₂Cu₃O_10+xwhisker at room temperature

Abstract

We report the observation of a phase transformation which can occur in a microscopic double phase BSCCO whisker at room temperature. We performed electrical resistivity measurements by thermally cycling the whisker in the range 78-300 K in a helium atmosphere and observed a decrease of the Bi-2223 phase amount in favour of the Bi-2212 phase, accompanied by an increase in the T c of the Bi-2212 phase. A longer ageing of the whisker increased its resistance by about a factor of four at room temperature and caused a semiconducting behaviour at low temperature. We demonstrate that a simple electrical model can account for the experimental data and disentangle the contributions of the two phases.

Doping Change in the Bi-2212 Superconductor Directly Induced by a Hard X-ray Nanobeam

“…Moreover, the approximation sin 2 θ ≈ tg 2 θ used to predict the peak positions according to eq S.2 is likely responsible for our small systematic underestimation of the c-axis. Of course, this does not invalidate the general trend of our results, all the more so because the electric measurements do not show any trace of filamentary intergrowths of the Bi 2 Sr 2 Ca 2 Cu 3 O 10+δ (Bi-2223) phase, 24 which could affect the c-axis determination.…”

Photoconductivity experiments on superconducting Bi2Sr2CaCu2O8+xwhiskers

“…However, since the importance of the ageing process increases non-linearly in time [24,26,27], its possible effect on PPC measurements should be carefully considered in the data analysis.…”

“…On the other hand, it has already been clarified in the past that oxygen depletion is induced at the Ag/Bi-2212 interface by the presence of the metal contacts [34] and that such a phenomenon adds to or promotes the natural instability of the BSCCO whiskers [24,26]. However, only a temperature-independent increase of the ab-plane resistance can be expected from the reduction in the carrier density resulting from such processes.…”

Mapping of Structural Changes Induced by X-ray Nanopatterning via Nano-X-ray Diffraction and Corresponding Electrical Effects

“…This sample has undergone a single damage procedure consisting of an irradiation according a two-line raster scan with Δ y = 250 nm and Δ z = 250 nm, so that a square mesh was obtained for the impinging points of the beam on the crystal, with an irradiation time per point Δt = 500 s. Because of this geometrical arrangement, the irradiated portion of the crystal can be considered as a single block of homogeneous material with modified electrical properties that is electrically equivalent to a resistor placed in series with another one representing the nonirradiated regions of the crystal with their pristine electrical properties. Analogous electrical models have already been formulated in the past to interpret the photoconductivity effects and the phase instability of Bi-2212 microcrystals. , …”

“…Analogous electrical models have already been formulated in the past to interpret the photoconductivity effects and the phase instability of Bi-2212 microcrystals. 31,32 Figure 8 shows the electrical resistance R versus temperature T behavior measured for the sample before and after the irradiation. It is clear that the irradiation has increased the total resistance of the sample, which means that the resistivity of the irradiated part ρ irr is greater than the one of the pristine material ρ.…”