Structural instability and superconductivity of the (Nd,Gd,Ce)(2)CuO4 system

摘要

The influence of partial substitution of Nd by Gd and Ce on the Nd2CuO4 n-type superconductor was studied by using X-ray diffraction measurements. For x = 0.15 Ce the maximum value of critical transition temperature Tc was obtained. The influence of Gd concentration on the lattice parameters and unit-cell volume was studied in the optimal doped sample (x = 0.15 Ce) and in the samples with 0 <= x <= 0.2 Ce.The relation between structural parameters and critical transition temperature was evidenced. The transition from the structural normal phase to the distortion phase was evidenced above y = 0.75 Gd in the optimal Ce-doped sample.