Stacking Variants and Superconductivity in the Bi–O–S System

Abstract

High-temperature superconductivity has a range of applications from sensors to energy distribution. Recent reports of this phenomenon in compounds containing electronically active BiS₂ layers have the potential to open a new chapter in the field of superconductivity. Here we report the identification and basic properties of two new ternary Bi–O–S compounds, Bi₂OS₂ and Bi₃O₂S₃. The former is non-superconducting; the latter likely explains the superconductivity at <i>T</i>_c = 4.5 K previously reported in “Bi₄O₄S₃”. The superconductivity of Bi₃O₂S₃ is found to be sensitive to the number of Bi₂OS₂-like stacking faults; fewer faults correlate with increases in the Meissner shielding fractions and <i>T</i>_c. Elucidation of the electronic consequences of these stacking faults may be key to the understanding of electronic conductivity and superconductivity which occurs in a nominally valence-precise compound