Title: Ligand dynamics control structure, elasticity, and high-pressure behavior of nanoparticle superlattices

Abstract

Precise engineering of nanoparticle superlattices (NPSLs) for energy applications requires a molecular-level understanding of the physical factors governing their morphology, periodicity, mechanics, and response to external stimuli. Such knowledge, particularly the impact of ligand dynamics on physical behavior of NPSLs, is still in its infancy. Here in this paper, we combine coarse-grained molecular dynamics simulations, and small angle X-ray scattering experiments in a diamond anvil cell to demonstrate that coverage density of capping ligands (i.e., number of ligands per unit area of a nanoparticle's surface), strongly influences the structure, elasticity, and high-pressure behavior of NPSLs using face-centered cubic PbS-NPSLs as a representative example. We demonstrate that ligand coverage density dictates (a) the extent of diffusion of ligands over NP surfaces, (b) spatial distribution of the ligands in the interstitial spaces between neighboring NPs, and (c) the fraction of ligands that interdigitate across different nanoparticles. We find that below a critical coverage density (1.8 nm-2 for 7 nm PbS NPs capped with oleic acid), NPSLs collapse to form disordered aggregates via sintering, even under ambient conditions. Above the threshold ligand coverage density, NPSLs surprisingly preserve their crystalline order even under high applied pressures (~40–55 GPa), and show a completely reversible pressuremore » behavior. This opens the possibility of reversibly manipulating lattice spacing of NPSLs, and in turn, finely tuning their collective electronic, optical, thermo-mechanical, and magnetic properties.« less

Authors:

Patra, Tarak K.  ^[1];

• Search DOE PAGES for author "Patra, Tarak K."
• Search DOE PAGES for ORCID "0000-0002-6002-0922"

Chan, Henry  ^[1];

• Search DOE PAGES for author "Chan, Henry"
• Search DOE PAGES for ORCID "0000-0002-8198-7737"

Podsiadlo, Paul ^[1]; Shevchenko, Elena V.  ^[1];

• Search DOE PAGES for author "Shevchenko, Elena V."
• Search DOE PAGES for ORCID "0000-0002-5565-2060"

Sankaranarayanan, Subramanian K. R. S.  ^[1];

• Search DOE PAGES for author "Sankaranarayanan, Subramanian K. R. S."
• Search DOE PAGES for ORCID "0000-0002-9708-396X"

Narayanan, Badri  ^[2]

• Search DOE PAGES for author "Narayanan, Badri"
• Search DOE PAGES for ORCID "0000-0001-8147-1047"

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+ Show Author Affiliations

1. Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials
2. Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division; Univ. of Louisville, KY (United States). Dept. of Mechanical Engineering

Publication Date:

Fri Mar 01 00:00:00 EST 2019

Research Org.:

Argonne National Laboratory (ANL), Argonne, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1542131

Alternate Identifier(s):

OSTI ID: 1498172

Grant/Contract Number:  

AC02-06CH11357; LDRD-2017-012-N0

Resource Type:

Accepted Manuscript

Journal Name:

Nanoscale

Additional Journal Information:

Journal Volume: 11; Journal Issue: 22; Journal ID: ISSN 2040-3364

Publisher:

Royal Society of Chemistry

Country of Publication:

United States

Language:

English

Subject:

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 77 NANOSCIENCE AND NANOTECHNOLOGY