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Title: Pressure-driven mechanical anisotropy and destabilization in zeolitic imidazolate frameworks

Here, the anisotropic mechanical response of ZIF-8 and ZIF-67 is investigated as a function of pressure and its main features (including shear-destabilization eventually leading to amorphization) discussed in terms of specific lattice vibrations and structural changes occurring in the framework. At zero pressure, the two ZIFs are characterized by an elastic anisotropy with directions of maximum and minimum stiffness along < 111 > and < 100 >, respectively. At P = 0.2 GPa, the framework exhibits a perfectly isotropic mechanical response, while at P > 0.2 GPa a different (complementary) anisotropic response is observed with directions of maximum and minimum stiffness along < 100 > and < 111 >, respectively. The bulk modulus of the two ZIFs initially slightly increases up to 0.1 GPa of pressure and then decreases at higher pressures. Amorphization in both ZIF-8 and ZIF-67 is confirmed to be due to the pressure-driven mechanical instability of their frameworks to shear deformations. The directional elastic moduli of the two ZIFs are partitioned into contributions from specific normal modes of vibration. The elastic constants C 11, and C 12 [and thus the bulk modulus K = 1/3(C 11+2C 12)] are mostly affected by symmetric “gate-opening” vibrations of the imidazolatemore » linkers in the four-membered rings. The C 44 shear elastic constant (and thus the mechanical instability and amorphization of the framework) are instead related to asymmetric “gate-opening” vibrations of the four-membered rings.« less
Authors:
 [1] ; ORCiD logo [2] ;  [3] ;  [1]
  1. Univ. di Torino, Torino (Italy)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Univ. of Vermont, Burlington, VT (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 99; Journal Issue: 1; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1502590
Alternate Identifier(s):
OSTI ID: 1489844

Maul, Jefferson, Ryder, Matthew R., Ruggiero, Michael T., and Erba, Alessandro. Pressure-driven mechanical anisotropy and destabilization in zeolitic imidazolate frameworks. United States: N. p., Web. doi:10.1103/PhysRevB.99.014102.
Maul, Jefferson, Ryder, Matthew R., Ruggiero, Michael T., & Erba, Alessandro. Pressure-driven mechanical anisotropy and destabilization in zeolitic imidazolate frameworks. United States. doi:10.1103/PhysRevB.99.014102.
Maul, Jefferson, Ryder, Matthew R., Ruggiero, Michael T., and Erba, Alessandro. 2019. "Pressure-driven mechanical anisotropy and destabilization in zeolitic imidazolate frameworks". United States. doi:10.1103/PhysRevB.99.014102.
@article{osti_1502590,
title = {Pressure-driven mechanical anisotropy and destabilization in zeolitic imidazolate frameworks},
author = {Maul, Jefferson and Ryder, Matthew R. and Ruggiero, Michael T. and Erba, Alessandro},
abstractNote = {Here, the anisotropic mechanical response of ZIF-8 and ZIF-67 is investigated as a function of pressure and its main features (including shear-destabilization eventually leading to amorphization) discussed in terms of specific lattice vibrations and structural changes occurring in the framework. At zero pressure, the two ZIFs are characterized by an elastic anisotropy with directions of maximum and minimum stiffness along < 111 > and < 100 >, respectively. At P = 0.2 GPa, the framework exhibits a perfectly isotropic mechanical response, while at P > 0.2 GPa a different (complementary) anisotropic response is observed with directions of maximum and minimum stiffness along < 100 > and < 111 >, respectively. The bulk modulus of the two ZIFs initially slightly increases up to 0.1 GPa of pressure and then decreases at higher pressures. Amorphization in both ZIF-8 and ZIF-67 is confirmed to be due to the pressure-driven mechanical instability of their frameworks to shear deformations. The directional elastic moduli of the two ZIFs are partitioned into contributions from specific normal modes of vibration. The elastic constants C11, and C12 [and thus the bulk modulus K = 1/3(C11+2C12)] are mostly affected by symmetric “gate-opening” vibrations of the imidazolate linkers in the four-membered rings. The C44 shear elastic constant (and thus the mechanical instability and amorphization of the framework) are instead related to asymmetric “gate-opening” vibrations of the four-membered rings.},
doi = {10.1103/PhysRevB.99.014102},
journal = {Physical Review B},
number = 1,
volume = 99,
place = {United States},
year = {2019},
month = {1}
}

Works referenced in this record:

Symmetric and Asymmetric Zeolitic Imidazolate Frameworks (ZIFs)/Polybenzimidazole (PBI) Nanocomposite Membranes for Hydrogen Purification at High Temperatures
journal, June 2012
  • Yang, Tingxu; Shi, Gui Min; Chung, Tai-Shung
  • Advanced Energy Materials, Vol. 2, Issue 11, p. 1358-1367
  • DOI: 10.1002/aenm.201200200