Design of metastable oxychalcogenide phases by topochemical (de)intercalation of sulfur in La2O2S2

Shunsuke Sasaki,Catherine Guillot-Deudon,Lukáš Palatinus,Gwladys Steciuk,Maria Teresa Caldes,Etienne Janod,Benoît Corraze,Gilles Frapper,Isabelle Braems,Eric Gautron,Stéphane Jobic,Laurent Cario

doi:10.1038/s41467-021-23677-w

Abstract

Designing and synthesising new metastable compounds is a major challenge of today’s material science. While exploration of metastable oxides has seen decades-long advancement thanks to the topochemical deintercalation of oxygen as recently spotlighted with the discovery of nickelate superconductor, such unique synthetic pathway has not yet been found for chalcogenide compounds. Here we combine an original soft chemistry approach, structure prediction calculations and advanced electron microscopy techniques to demonstrate the topochemical deintercalation/reintercalation of sulfur in a layered oxychalcogenide leading to the design of novel metastable phases. We demonstrate that La2O2S2 may react with monovalent metals to produce sulfur-deintercalated metastable phases La2O2S1.5 and oA-La2O2S whose lamellar structures were predicted thanks to an evolutionary structure-prediction algorithm. This study paves the way to unexplored topochemistry of mobile chalcogen anions.

Highlights

Designing and synthesising new metastable compounds is a major challenge of today’s material science
In that respect the stunning discovery of the superconducting nickelate, Nd0.8Sr0.2NiO2, has recently spotlighted the benefit of this topochemical approach[12]. Such reactions were mainly limited to oxides and no topochemical deintercalation of sulfur at low temperature leading to metastable phases was reported
Its structure consists of fluorite-type 2/∞[La2O2]2+ infinite layers separated from each other by discrete (S2)2- sulfur dimers aligned in parallel to these 2D blocks[18]

Summary

Introduction

Designing and synthesising new metastable compounds is a major challenge of today’s material science. Such reactions were mainly limited to oxides and no topochemical deintercalation of sulfur at low temperature leading to metastable phases was reported.

Results

Conclusion