On the Crystal Structure of Colloidally Prepared Metastable Ag2Se Nanocrystals
收藏资源简介：
Structural polymorphism is known for many bulk materials; however, on the nanoscale metastable polymorphs tend to form more readily than in the bulk, and with more structural variety. One such metastable polymorph observed for colloidal Ag<sub>2</sub>Se nanocrystals has traditionally been referred to as the “tetragonal” phase of Ag<sub>2</sub>Se. While there are reports on the chemistry and properties of this metastable polymorph, its crystal structure, and therefore electronic structure, has yet to be determined. We report that an anti-PbCl<sub>2</sub>-like structure type (space group <em>P</em>2<sub>1</sub>/<em>n</em>) accurately describes the powder X-ray diffraction and X-ray total scattering patterns of colloidal Ag<sub>2</sub>Se nanocrystals prepared by several different methods. Density functional theory (DFT) calculations indicate that the anti-PbCl<sub>2</sub>-like Ag<sub>2</sub>Se polymorph is a dynamically stable, narrow-band gap semiconductor. DFT results reveal a dense theoretical Ag<sub>2</sub>Se phase space with many low-energy polymorphs, which helps explain the large number of polymorphs reported in the literature. Analysis and calculation data are stored in the zip archive. The `ag2se-calcs.aiida.` contains the provenance of the calculations and can be imported into an AiiDA database instance. The antiPbCl2like_Ag2Se_laboratory.cif file is the Reitveld refined Ag2Se structure starting from the PbCl<sub>2</sub> structure.<br> Also hosted on GitHub with minor revisions. Published paper: https://doi.org/10.1021/acs.nanolett.1c02045
