CONDUCTIVITY AND PHOTOCONDUCTIVITY EXPERIMENTS IN AGED BSCCO WHISKERS.

One of the most famous high¿Tc superconductors is the Bi2Sr2Ca1Cu2O8+? compound, discovered in 1987 and characterized by a typical critical temperature of about 80 K. The BSCCO whisker is a single crystal distinguished by perfect crystallography, peculiar crystal size with extremely small cross section of about 1 mm2 and excellent superconducting properties, therefore a study of the light effect on these structures could be interesting. All the previous works about the photoconductivity experiments on the BSCCO whiskers had negative results. Nevertheless, photoconductivity presence in very defective BSCCO samples, like the Grain Boundary Junction (GBJ) in the polycrystalline structures, was observed by some research groups. In particular, one of these, which belongs to the University of Nice¿Sophia Antipolis, collaborates with the Turin high¿Tc superconductors group, because of their experience about the photodoping effects in thin films of another well¿known high¿Tc superconductor, the YBCO compound, for which photoconductivity phenomena were widely observed. Based on these facts, the aim of this thesis work is to produce very defective samples and to verify whether these are suitable for the photoconductivity phenomena observation in the BSCCO whisker structure. The work was divided into two parts: the whisker assembling and the electrical characterization, respectively carried out at the General Chemistry and Experimental Physics Departments of the University of Turin, and the photoconductivity measurements, which were performed at the Laboratoire de Physique de la Matière Condensée (LPMC), under the Nice Sophia Antipolis University.