Supervisors info:
Δημοσθένης Σταμόπουλος, Αναπληρωτής Καθηγητής, τμήμα Φυσικής, ΕΚΠΑ
Μαρία Καλαμιώτου, Καθηγήτρια, τμήμα Φυσικής, ΕΚΠΑ
Εμμανουήλ Συσκάκης, Επίκουρος Καθηγητής, τμήμα Φυσικής, ΕΚΠΑ
Summary:
We examined the most suitable conditions for the preparation of a hybrid material composed of the superconductor YBCO, YBa2Cu3O7-δ, where 0.07≤δ≤0.1 to achieve maximum critical temperature Tc, in a piezoelectric matrix of PZT, Pb [ZrxTi1-x]O3, x=0.52. The purpose for the final product is (a) the piezoelectric material to acquire the best properties (e.g. maximum piezoelectric coefficients, dij), (b) the superconductor to maintain optimum properties (e.g. maximum critical temperature, TC) and (c) the piezo-superconducting hybrid system to be sufficiently compact as to allow manipulation while taking the necessary measurements (e.g. magnetic susceptibility measurements, measurements on the optical microscope under the application of voltage etc). In this direction we studied in detail (a) the sintering protocol (temperature and duration) and possible successive stages of (pre)preparation, both the piezoelectric and the superconductor and (b) their proportion in the final hybrid system and the sintering protocol (temperature and duration). Ιn this study, various sets of samples were prepared in order to control, as much as possible, all parameters before determining the precise way of synthesis of the desired hybrid material. The experimental techniques that were used are solid state chemistry, SQUID magnetometry, x-ray diffraction and optical microscopy. From the study we conducted, we assume, concerning the independent preparatory piece the piezoelectric, PZT, and the superconductor, YBCO, that (a) the PZT to be used should be pretreated, ie pro-sintering at 1180oC for 24h and (b) the YBCO, should be synthesized at 920oC (as is known from the literature). About the composition of the hybrid material (c) the ratio of YBCO on the PZT needs not to exceed from 15/85 and (d) the final system should be sintered at Tsinfin = 860oC. Τhe ultimate ανδ future objective of this study is that with the suggested hybrid material there is a way to control superconductivity, not by applying an external magnetic field, as it is already possible, but with the application of an external electric field to the piezoelectric matrix.
Keywords:
Hybrid, Piezoelectricity, PZT, Superconductivity, YBCO, Diamagnetism