Etude des effets du dopage par du Ca sur les propriétés de la céramique supraconductrice YBa2Cu3O7-δ

Abstract

In this work, we have elaborated superconductor compound Y1-xCaxBa2Cu3O7-δ with x= 0.00, 0.01, 0.02, from the oxides (Y2O3, CuO,) and the carbonate BaCO3. The specimens were prepared by the conventional solid state reaction. In order to characterize these specimens, the following experimental techniques were used: X ray diffraction (DRX) scanning electron microscopy (SEM) and measurements of resistivity ρ(T). The spectras of XRD show, after calcination, the presence of Y123 phase with a majority fraction, accompanied by the parasite phase BaCuO2 (Y011). After the sintering treatment, the spectras of pellets witch elaborated under pressure of 1 tonn/cm2 at 940°C during 24h, give also Y123 with Y011 phase. The fraction of Y011 phase decrease with the increasing of ca concentration until its disappearance at ca. The indexing of spectra, using CELREF software, show that the structure of samples is orthorhombic, and the cell parameters a and c decrease with the increasing of the ca concentration, when the b parameter increase. The SEM micrographics show the zinc influence on the structure of the phase, decreasing of the pores with the increasing of the concentration of Zn, and also the change of size and form of grains. Finally, the measurements of resistivity confirm the superconductive character of the prepared samples.and show the effect of Zn and ca on Tc.