# Superconductivity in Bi3O2S2Cl with Bi-Cl Planar Layers

## TL;DR

This paper reports the discovery of superconductivity in a new layered bismuth compound, Bi3O2S2Cl, which features unique Bi-Cl planar layers and can be tuned from semiconductor to superconductor by adjusting sulfur content.

## Contribution

It introduces a novel layered structure with Bi-Cl planar layers and demonstrates superconductivity in this new compound, expanding the family of bismuth-based superconductors.

## Key findings

- Superconductivity observed at 2.6-3.5 K in Bi3O2S2Cl
- Superconductivity is enhanced with less sulfur or higher synthesis temperature
- The compound can be tuned from semiconductor to superconductor by sulfur content

## Abstract

A quaternary compound Bi3O2S2Cl, which consists of novel [BiS2Cl]2-layers, is reported. It adopts a layered structure of the space group I4/mmm (No. 139) with lattice parameters: a = 3.927(1) {\AA}, c = 21.720(5) {\AA}. In this compound, bismuth and chlorine atoms form an infinite planar layer, which is unique among the bismuth halides. Superconductivity is observed in both polycrystals and single crystals, and is significantly enhanced in the samples prepared with less sulfur or at higher temperatures. By tuning the content of sulfur, Bi3O2S2Cl can be converted from a semiconductor into a superconductor. The superconducting critical temperature ranges from 2.6 K to 3.5 K. Our discovery of the [BiS2Cl]2- layer opens another door in searching for the bismuth compounds with novel physical properties.

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Source: https://tomesphere.com/paper/1903.02698