Effect of chemical substitution and external strain on phase stability and ferroelectricity in two dimensional M2CT2 MXenes
Document Type
Article
Publication Date
4-20-2022
Abstract
Two dimensional ferroelectric materials are gaining increasing attention for use in ultrathin electronic devices owing to the presence of a spontaneous polarization down to one or two monolayers. However, such materials are difficult to identify, especially those with out-of-plane electric polarizations. Previous work predicted that a metastable ferroelectric phase exists in the 2D MXene Sc2CO2, while further studies have predicted that this phase exists in other MXene chemistries. However, questions remain about the origin of ferroelectricity, the stability of this phase relative to other competing phases, and the effect of external stimuli in these materials. In this work, we use density functional theory calculations to investigate 12 M2CT2 MXenes (M = transition metal, T = surface terminating group) and determine which have the ferroelectric phase as their ground state. We compute these materials’ polarizations, densities of states, phonon band structures, Bader charges, and Born effective charges in the ferroelectric phase to elucidate the reasons for its stabilization. We demonstrate that this ferroelectric phase can be preferentially stabilized in non-ferroelectric MXenes through full chemical substitution of Sc or O, alloying of the Sc sites, or application of epitaxial strain. Finally, we show that these materials have excellent piezoelectric properties as well. This work provides a detailed understanding of ferroelectric MXenes and show how the number of 2D ferroelectric materials can be increased through chemical substitution or application of external stimuli.
Identifier
85129968826 (Scopus)
Publication Title
Nanoscale
External Full Text Location
https://doi.org/10.1039/d2nr00514j
e-ISSN
20403372
ISSN
20403364
PubMed ID
35468178
First Page
6970
Last Page
6980
Issue
18
Volume
14
Grant
TG-DMR200002
Fund Ref
Argonne National Laboratory
Recommended Citation
Li, Mo; Omisakin, Olamide; and Young, Joshua, "Effect of chemical substitution and external strain on phase stability and ferroelectricity in two dimensional M2CT2 MXenes" (2022). Faculty Publications. 3004.
https://digitalcommons.njit.edu/fac_pubs/3004