Physical Properties of Holmium Promoted Superconductivity in Nd-Doped YBCO HT_C-Superconductors

Authors: MORSY ABOU SEKKINA, ABDUL RAOUF TAWFIK, OSAMA HEMEDA, MOHAMAD AHMAD TAHER DAWOUD, SAMY EL-ATTAR

Abstract: Samples of the nominal composition (Y_{0.5}Nd_{0.5-x}Ho_x) Ba_2Cu_3O_{7- \delta} , 0 \le x \le 0.5, have been prepared using the conventional solid state reaction. The effect of holmium and neodymium substitution on electrical resistivity, transition temperature T_c, lattice parameters, size of crystallite and grain size has been investigated. X-ray diffraction, electron micro-probe, scanning electron microscope and IR spectra, have been used in our investigation. The results show that the transition temperature T_c, electron-hole jump rate and lattice parameters (a, b) have minimum values at x = 0.2, while c increases to maximum at x = 0.2. The size of crystallite, the electrical resistivity and grain size are also maximum at x = 0.2. The real composition, molecular state and electronic state of the prepared samples are discussed.

Keywords: Superconductors; X-ray; IR-spectra; YBCO; Ho; Nd.

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