Quantifying thermal disorder in metal-organic frameworks: lattice dynamics and molecular dynamics simulations of hybrid formate perovskites
File(s)
Published version
Author(s)
Svane, KL
Walsh, A
Type
Journal Article
Abstract
Hybrid organic–inorganic materials are mechanically soft, leading to large thermoelastic effects which can affect properties such as electronic structure and ferroelectric ordering. Here we use a combination of ab initio lattice dynamics and molecular dynamics to study the finite temperature behavior of the hydrazinium and guanidinium formate perovskites, [NH2NH3][Zn(CHO2)3] and [C(NH2)3][Zn(CHO2)3]. Thermal displacement parameters and ellipsoids computed from the phonons and from molecular dynamics trajectories are found to be in good agreement. The hydrazinium compound is ferroelectric at low temperatures, with a calculated spontaneous polarization of 2.6 μC cm–2, but the thermal movement of the cation leads to variations in the instantaneous polarization and eventually breakdown of the ferroelectric order. Contrary to this the guanidinium cation is found to be stationary at all temperatures; however, the movement of the cage atoms leads to variations in the electronic structure and a renormalization in the bandgap from 6.29 eV at 0 K to an average of 5.96 eV at 300 K. We conclude that accounting for temperature is necessary for quantitative modeling of the physical properties of metal–organic frameworks.
Date Issued
2016-12-12
Date Acceptance
2016-12-12
Citation
Journal of Physical Chemistry C, 2016, 121 (1), pp.421-429
ISSN
1932-7455
Publisher
American Chemical Society
Start Page
421
End Page
429
Journal / Book Title
Journal of Physical Chemistry C
Volume
121
Issue
1
Copyright Statement
© 2016 American Chemical Society. This is an open access article published under a Creative Commons Attribution (CC-BY) License (http://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html) , which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.
Sponsor
The Royal Society
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000392035500046&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Grant Number
UF150657
Subjects
Science & Technology
Physical Sciences
Technology
Chemistry, Physical
Nanoscience & Nanotechnology
Materials Science, Multidisciplinary
Chemistry
Science & Technology - Other Topics
Materials Science
WEAK FERROMAGNETISM
PHASE-TRANSITION
HIGH-TEMPERATURE
FERROELECTRICITY
ARCHITECTURE
STATE
SOLIDS
ORDER
Physical Chemistry
09 Engineering
03 Chemical Sciences
10 Technology
Publication Status
Published