Superconducting properties of Ce-substituted TaSr2(Gd,Ce)2 $${\rm Cu}_2{\rm O}_y$$

Abstract

A layered cuprate TaSr2\({\rm Gd}_{1+x}\)\({\rm Ce}_{1-x}\)Cu2\({\rm O}_y\) for x = 0.4–0.8 has been successfully synthesized by solid state reaction. X-ray powder diffraction analysis indicates that nearly all the peaks from the samples can be indexed to a single phase of Ta-1222. The sample with nominal composition TaSr2Gd1.6Ce0.4Cu2\({\rm O}_y\) showed a tetragonal structure with lattice parameters a = 3.858 A, c = 28.81 A with space group most likely I4/mmm. The TaSr2\({\rm Gd}_{1+x}\)\({\rm Ce}_{1-y}\)Cu2\({\rm O}_y\) compound exhibits a narrow superconducting region near x = 0.6 with Tc-onset = 30 and Tc-zero=10 K as determined by d.c. electrical resistance versus temperature measurements.