Synthesis protocol and superconducting properties of (Hg,Cr)Sr₂CuO_4+δ

Abstract

In this paper, we report the study of our results on the synthesis protocol and the superconducting properties of (Hg, Cr)Sr 2 CuO 4+δ . We have used several distinct approaches for the synthesis of good quality (Hg, Cr)/Sr-1201 samples by varying the processing parameters such as starting materials, precursor and annealing treatments as well as the sample container. The (Hg, Cr)/Sr-1201 samples were synthesized in partial vacuum, and systematically characterized by powder XRD, χ -T , dc-electrical-resistance and dc-magnetization measurements. XRD data confirm that they are of tetragonal Hg/Ba-1201 type structure. Good quality (Hg, Cr)/Sr-1201 samples were obtained from the sample prepared using a strontium nitrate source with a maximum T onset c ∼ 60 K, which is higher than the samples prepared using a carbonate source (T onset c ∼ 56 K). It is found that T c is not affected by the subsequent Ar or O 2 annealing treatment. Remarkably, the annealed samples show significant improvement in the diamagnetic transition.