A theoretical study of the Pnma and R3m phases of Sb2S3, Bi2S3, and Sb2Se3

We report a comparative theoretical study of the Pnma and R3m phases of Sb2S3, Bi2S3, and Sb2Se3 close to ambient pressure. Our enthalpy calculations at 0 K show that at ambient pressure the R3m (tetradymite-like) phase of Sb2Se3 is energetically more stable than the Pnma phase, contrary to what is...

Full description

Saved in:
Bibliographic Details
Published in:Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2022-10, Vol.10 (40), p.15061-15074
Main Authors: Lora da Silva, E, Skelton, J M, Rodríguez-Hernández, P, Muñoz, A, Santos, M C, Martínez-García, D, Vilaplana, R, Manjón, F J
Format: Article
Language:English
Subjects:
Antimony compounds
Bismuth sulfides
Crystal structure
Enthalpy
Free energy
Infrared spectra
Mathematical analysis
Phases
Pressure
Selenides
Temperature dependence
Tensors
Unit cell
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We report a comparative theoretical study of the Pnma and R3m phases of Sb2S3, Bi2S3, and Sb2Se3 close to ambient pressure. Our enthalpy calculations at 0 K show that at ambient pressure the R3m (tetradymite-like) phase of Sb2Se3 is energetically more stable than the Pnma phase, contrary to what is observed for Sb2S3 and Bi2S3, and irrespective of the exchange–correlation functional employed in the calculations. The result for Sb2Se3 is in contradiction to experiments in which all three compounds are usually grown in the Pnma phase. This result is further confirmed by free-energy calculations taking into account the temperature dependence of unit-cell volumes and phonon frequencies. Lattice dynamics and elastic tensor calculations further show that both the Pnma and R3m phases of Sb2Se3 are dynamically and mechanically stable at zero applied pressure. Since these results suggest that the formation of the R3m phase of Sb2Se3 should be feasible under close to ambient conditions, we provide a theoretical crystal structure and simulated Raman and infrared spectra to help in its identification. We also discuss the results of the two published works that have claimed to have synthesized tetradymite-like Sb2Se3. Finally, the stability of the R3m phase across the three group-15 A2X3 sesquichalcogenides is analysed based on their van der Waals gap and X–X in-plane geometry.
ISSN:2050-7526
2050-7534
DOI:10.1039/d2tc01484j