On the Chemical Bonding of Amorphous Sb2Te3

• Published in: Physica status solidi. PSS-RRL. Rapid research letters 2021-03, Vol.15 (3), p.n/a
• Main Authors: Mocanu, Felix C., Konstantinou, Konstantinos, Mavračić, Juraj, Elliott, Stephen R.
• Format: Article
• Language: English
• Subjects: chemical bondings; density-functional theory; molecular dynamics; phase-change memories
• ISSN: 1862-6254; 1862-6270
• DOI: 10.1002/pssr.202000485

An analysis of the electronic structure and chemical bonding in glassy Sb2Te3 is carried out by means of density functional theory calculations, on a computer model generated by ab initio molecular dynamics. A significant antibonding character of electronic states below the Fermi level is observed, which is the characteristic feature of phase‐change memory materials. Near‐linear chains, with alternating long and short bonds, are found to be an important geometric structural pattern related to this antibonding signature. The electronic structure and chemical bonding analysis, herein, reveals an emergent character of hypervalent interactions in the amorphous phase of Sb2Te3. The intimate link between these near‐linear chains, hypervalent interactions, and the fast‐switching properties of this technologically important material provides valuable information for the future development of phase‐change memory materials. A computer model of amorphous Sb2Te3 contains a network of near‐linear chains that comprises nearly half of its atoms. Most of the chains consist of three atoms, with several longer chains observed as well. They show hypervalent‐bonding interactions which contribute to the antibonding character of electronic states below the Fermi level and the fast‐switching properties of this material.