Fig. 3: Incomplete intercalation and deintercalation of sulfur.

a Schematic representation of incomplete intercalation of sulfur into oA-La₂O₂S and deintercalation of sulfur from La₂O₂S₂ that leads to an intermediate compound La₂O₂S_1.5. b Intercalation experiments of sulfur into oA-La₂O₂S. Experimental XRD patterns of pure oA-La₂O₂S and of the products of its mixture with sulfur (0.5 or 1 equiv. of S) after thermal treatments at 150 or 200 °C. The new XRD peaks emerging after the thermal treatment with 0.5 S are marked by *. c Deintercalation of sulfur from La₂O₂S₂. Experimental XRD patterns of La₂O₂S₂ and of the product of its mixture with Rb⁰, Ag⁰, and Ni⁰ after the thermal treatments at 200 or 350 °C. The XRD peaks of minor by-products are marked as follows: ● = Ag₂S³⁷, ■ = α-NiS³⁸.