Flux Growth and Superconducting Properties of (Ce,Pr)OBiS₂ Single Crystals

Ce_1- Pr OBiS₂ (0. 1 ≤ x ≤ 0.9) single crystals were grown using a CsCl flux method. Their structural and physical properties were examined by X-ray diffraction, X-ray absorption, transmission electron microscopy, and electrical resistivity. All of the Ce_1- Pr OBiS₂ single crystals with 0.1 ≤ x ≤ 0.9 exhibited tetragonal phase. With increasing Pr content, the a-axis and c-axis lattice parameters decreased and increased, respectively. Transmission electron microscope analysis of Ce_0.1Pr_0.9OBiS₂ (x = 0.9) single crystal showed no stacking faults. Atomic-resolution energy dispersive X-ray spectrometry mapping revealed that Bi, Ce/Pr, O, and S occupied different crystallographic sites, while Ce and Pr randomly occupied the same sites. X-ray absorption spectra showed that an increase of the Pr ratio increased the ratio of Ce⁴⁺/Ce³⁺. All of the Ce_1- Pr OBiS₂ crystals showed superconducting transition, with a maximum transition temperature of ~4 K at x = 0.9.