Crystal Structure of Colloidally Prepared Metastable Ag2Se Nanocrystals.
Nano Lett
; 21(13): 5881-5887, 2021 Jul 14.
Article
in En
| MEDLINE
| ID: mdl-34196567
ABSTRACT
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 Ag2Se nanocrystals has traditionally been referred to as the "tetragonal" phase. 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-PbCl2-like structure type (space group P21/n) more accurately describes the powder X-ray diffraction and X-ray total scattering patterns of colloidal Ag2Se nanocrystals prepared by several different methods. Density functional theory (DFT) calculations indicate that this anti-PbCl2-like Ag2Se polymorph is a dynamically stable, narrow-band-gap semiconductor. The anti-PbCl2-like structure of Ag2Se is a low-lying metastable polymorph at 5-25 meV/atom above the ground state, depending on the exchange-correlation functional used.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Nano Lett
Year:
2021
Document type:
Article
Affiliation country:
United States