SYNTHESIS AND CHARACTERIZATION OF CUPRATE SUPERCONDUCTORS

Abstract

In the first chapter we have discussed the history of the superconductors. In 1911 first superconductor was invented but the Cuprate based superconductors were invented in 1986, which comes under the high temperature super conductors' category. In 1988 high temperature superconductor using thallium invented. Although thallium is toxic in nature but due to its high critical temperature Tc (>20 K) scientist shows their interest in this compound. Properties of superconductors also discussed in this chapter. In the second chapter we discuss the various synthesis and characterization techniques that are used in the dissertation. In the Synthesis techniques part we have discussed solid state reaction method, pulse laser deposition method and spray pyrolysis method. The single phase nature and crystallinity is determined by X-ray diffraction technique. X-Ray diffraction data was obtained with the help of X - Ray diffractomter (BRUKER AXS D - 8). XRD data can be analyzed to determine the lattice parameters, particle size and strain. Field emission scanning electron microscopy (FESEM) Model FEI Quanta 200F is used to determine the surface morphology of the samples. It uses the electric field effect in order to produce the electrons. These electrons eject the secondary electrons from the object which are used in the image formation of the samples. Energy dispersive X - ray analyzer (EDX) technique confirms the stoichiometry of the sample. Four probe method because of its advantage of rectifying contact resistance is used for the measurement of electrical resistance. Four probe method uses the procedure in which the current is provided from the outer probes and voltage is measured from the inner two probes. SQUID magnetometer (MPMS XL Quantum) is used for plotting the M - H loop at 50 K and 70K. SQUID comprises superconductors separated by the insulating layer which creates the Josephson junction. ff In the third chapter we have discussed the behavior of YiCaBa2Cu307 (x0.0. 0.1, 0.2, 0.3) superconductor by magnetic measurements and plotted the M-H loop at 50 K and 70 K. With the help of this M-I-1 loop we obtained critical current density (Jc). In the fourth chapter we have made T12Ba2Ca2Cu3O10 film on the MgO substrate by PLD method and on ZrO2 substrate by spray pyrolysis method. Film synthesis and characterization have been discussed in this chapter. Characterization of samples has been carried out by XRD, FE-SEM, EDX, R-T and AFM. In the fifth chapter synthesis and characterization of YBa2PrCu307 (x0, 0.1) superconductors have been discussed. Synthesis has been done by solid state reaction method and characterization has been carried out by XRD, FE-SEM, EDX, R-T.