X-ray powder diffraction, scanning electron microscopy （SEM）, energy dispersive X-ray, electrical resistivity and AC-magnetic susceptibility measurements have been performed for polycrystalline superconducting sampl...X-ray powder diffraction, scanning electron microscopy （SEM）, energy dispersive X-ray, electrical resistivity and AC-magnetic susceptibility measurements have been performed for polycrystalline superconducting samples of type TIBa2Ca2_xSCxCU309_δ （0.0 ≤ x 〈 0.6）. The powder X-ray diffractograms indicate that the tetragonal structure of T1-1223 is not affected by Sc-substitution whereas the lattice parameters are changed. The X-ray analysis indicates that the low-contents of scandium （x） enhance the formation of T1-1223 and reduce the secondary phases. The grain-size determined by SEM decreases as x increases. The electrical resistivity measurements show suppression in the superconducting transition temperature, Tc, and an increase in both the residual resistivity and the superconducting transition width as x increases. The suppression in Tc is attributed to the hole-filling mechanism.展开更多
The thermomechanical analysis （TMA） of Cu0.5T10.5Ba2Ca2-xRxCu30110-δ, where R=Pr and La, with 0.0〈x〈0.15, was carried out in temperature range from 450 to 1145 K. The samples were prepared by singlestep solid sta...The thermomechanical analysis （TMA） of Cu0.5T10.5Ba2Ca2-xRxCu30110-δ, where R=Pr and La, with 0.0〈x〈0.15, was carried out in temperature range from 450 to 1145 K. The samples were prepared by singlestep solid state reaction technique. The prepared samples were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The superconductivity of the prepared samples was investigated by electrical resistivity measurement. The results showed that low substitution content enhanced the （Cu0.5Tlo.5）- 1223 phase formation, while the higher substitution content degraded this phase. The higher superconducting transition temperatures Tc were found to be 114 K and 109 K at x= 0.025 for Pr- and La-substitutions, respectively. The average linear thermal expansion coefficient increased as x increased, while the shrinkage temperature decreased as x increased. Those results were emphasized by porosity and Vickers microhardness calculations. Debye temperature 0D was calculated from the linear thermal expansion coefficient data and correlated to Tc to estimate the electron-phonon coupling λep.展开更多
文摘X-ray powder diffraction, scanning electron microscopy （SEM）, energy dispersive X-ray, electrical resistivity and AC-magnetic susceptibility measurements have been performed for polycrystalline superconducting samples of type TIBa2Ca2_xSCxCU309_δ （0.0 ≤ x 〈 0.6）. The powder X-ray diffractograms indicate that the tetragonal structure of T1-1223 is not affected by Sc-substitution whereas the lattice parameters are changed. The X-ray analysis indicates that the low-contents of scandium （x） enhance the formation of T1-1223 and reduce the secondary phases. The grain-size determined by SEM decreases as x increases. The electrical resistivity measurements show suppression in the superconducting transition temperature, Tc, and an increase in both the residual resistivity and the superconducting transition width as x increases. The suppression in Tc is attributed to the hole-filling mechanism.
文摘The thermomechanical analysis （TMA） of Cu0.5T10.5Ba2Ca2-xRxCu30110-δ, where R=Pr and La, with 0.0〈x〈0.15, was carried out in temperature range from 450 to 1145 K. The samples were prepared by singlestep solid state reaction technique. The prepared samples were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The superconductivity of the prepared samples was investigated by electrical resistivity measurement. The results showed that low substitution content enhanced the （Cu0.5Tlo.5）- 1223 phase formation, while the higher substitution content degraded this phase. The higher superconducting transition temperatures Tc were found to be 114 K and 109 K at x= 0.025 for Pr- and La-substitutions, respectively. The average linear thermal expansion coefficient increased as x increased, while the shrinkage temperature decreased as x increased. Those results were emphasized by porosity and Vickers microhardness calculations. Debye temperature 0D was calculated from the linear thermal expansion coefficient data and correlated to Tc to estimate the electron-phonon coupling λep.
