Enhanced Critical Temperature Up to 87.5 K in the Single Crystals of the Incommensurate Spin-Ladder Cuprate Bi-Doped Sr\(_{10-x}\)Ca\(_x\)Cu\(_{17}\)O\(_{29+\delta }\)

Abstract

We report the growth of high-quality single crystals of the incommensurate spin-ladder system Bi-doped Sr\(_{10-x}\)Ca\(_x\)Cu\(_{17}\)O\(_{29+\delta }\) using an optimized self-flux pressure technique, exhibiting an enhanced superconducting transition temperature of T\(_c\) = 87.5 K compared to previous reports [1–5]. The as-grown crystals were systematically characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction (SCXRD) confirming their morphology and chemical homogeneity. Structural refinements confirm the incorporation of a small amount of Bi into the SCCO lattice through partial substitution of Bi\(^{3+}\) at the Sr\(^{2+}\)/Ca\(^{2+}\) sites while preserving the orthorhombic crystal structure. Magnetization and resistivity measurements revealed an improvement in the superconducting transition temperature of Bi-doped Sr\(_{10-x}\)Ca\(_x\)Cu\(_{17}\)O\(_{29}\) single crystals. The enhanced superconducting T\(_c\) is likely brought about by the optimized self-flux pressure technique process as well as Bi\(^{3+}\) substitution at the Sr\(^{2+}\)/Ca\(^{2+}\) sites resulting in a possible enhanced ladder-hole concentration in Bi-doped Sr\(_{10-x}\)Ca\(_x\)Cu\(_{17}\)O\(_{29}\) crystals.