Chemical interactions between Bi2Sr3CaO7(Bi-2310) and Bi2Sr2Ca0.8Dy0.2Cu2O8 (Bi-2212(Dy))

in Superconductor Science & Technology (2006), 19(1), 39-43

The chemical interactions between Bi2Sr3CaO7 (Bi-2310) and Bi2Sr2Ca0.8Dy0.2Cu2O8 (Bi-2212(Dy)) at 965 degrees C were investigated by means of: (i) an interdiffusion couple and (ii) layers deposited by dip ... [more ▼]

The chemical interactions between Bi2Sr3CaO7 (Bi-2310) and Bi2Sr2Ca0.8Dy0.2Cu2O8 (Bi-2212(Dy)) at 965 degrees C were investigated by means of: (i) an interdiffusion couple and (ii) layers deposited by dip coating on oxidized nickel Substrates. The samples were characterized by optical and electron microscopies, energy-dispersive x-ray (EDX) analysis and x-ray diffraction. It turns out that at the peritectic temperature Of Bi-2212(Dy), the Bi-2310 phase reacts with the liquid phase resulting from the peritectic decomposition of the Bi-2212(Dy) phase. Dissolution of Bi-2310 leads to an enrichment in Sr and an impoverishment in Cu of the liquid phase, resulting in a shift of the composition of the insoluble phase towards the Ca-rich end of the (Ca, Sr)O Solid Solution. [less ▲]

Transport properties of HgBaCaCuO(1223) polycrystalline superconductors

in Superconductor Science & Technology (1998), 11(1), 128-132

We report on the temperature (20-300 K) dependence of the resistivity, thermopower and thermal conductivity measurements of HgBaCaCuO(1223) polycrystalline superconductors with nominal composition Hg1 ... [more ▼]

We report on the temperature (20-300 K) dependence of the resistivity, thermopower and thermal conductivity measurements of HgBaCaCuO(1223) polycrystalline superconductors with nominal composition Hg1.4Ba2Ca2CU3O8+delta. We present some discussion of the precision and the originality of the measurement methods which are especially used to measure the electrical resistivity and simultaneously the thermopower and the thermal conductivity as a function of temperature. The superconductivity fluctuation contributions to the transport properties of the materials are calculated and compared. The results are related to the 2D anisotropy of the crystallographic structure. [less ▲]

ANISOTROPY OF THE MIXED-STATE IN TEXTURED PB-FREE BI-2223 SUPERCONDUCTOR - ELECTRICAL-RESISTIVITY, SEEBECK AND NERNST EFFECTS

in Superconductor Science & Technology (1995), 8(9), 726-739

Anisotropy of transport entropy and of Hall angle are reported for the first time through various electrical and thermal transport properties, such as the electric resistivity and the Seebeck and the ... [more ▼]

Anisotropy of transport entropy and of Hall angle are reported for the first time through various electrical and thermal transport properties, such as the electric resistivity and the Seebeck and the Nernst effects (in the presence of a magnetic field ranging between 0 and 4 T), measured for a Pb-free textured Bi-2223 system. The field and temperature influence in the mixed state region is reported only for the H parallel to a and H parallel to c cases and the temperature gradient applied along the b direction. A much stronger influence of magnetic field along the c than the a axis is demonstrated. The relative evolution of the so-called 'excess transport effects' is discussed. We show the laws relating the respective losses to the applied magnetic field. This leads us to the understanding that anisotropic vortex kinetics exist in these systems. We consequently propose two original routes of theoretical investigations to be considered for the calculation of Nernst and TEP effects in a field, in particular to consider a vortex-carrier drag phenomenon. [less ▲]

STUDY OF THE CRYSTALLIZATION PROCESS IN BI2-XPBXSR2CA2CU3O10-Y GLASS SYSTEMS - OPTICAL POLARIZED-LIGHT MICROSCOPY, ELECTRICAL AND MAGNETIC-PROPERTIES

in Superconductor Science & Technology (1993), 6(12), 850-857

Synthesis of Bi2-xPbxSr2Ca2Cu3O10-y (x = 0 and x = 0.3) has been performed using the glass recrystallization route technique. After splat quenching, the samples were annealed at 820, 850 or 870-degrees-C ... [more ▼]

Synthesis of Bi2-xPbxSr2Ca2Cu3O10-y (x = 0 and x = 0.3) has been performed using the glass recrystallization route technique. After splat quenching, the samples were annealed at 820, 850 or 870-degrees-C for 96 or 144 h (with one intermediary grinding). High-resolution polarization micrographs and electrical (and magnetic susceptibility) measurements have been taken. Various growth mechanisms can thus be checked, and the physical properties are studied in relation to the microstructure. It is found that the 2223 phase does not crystallize directly from the amorphous one but results from a dissolution-reprecipitation process. The stability of the 2212 phase is emphasized. The 2201 phase precipitates at high temperature and rapidly reacts with the melt to form the 2223 phase. The kinetics of the lead-substituted sample seems to be controlled by the Ca2PbO4 phase. which acts as a flux. [less ▲]