title: Stacking Faults and Mechanical Behavior beyond the Elastic Limit of an Imidazole-Based Metal Organic Framework: ZIF-8.
abstract: We determine the nonlinear mechanical behavior of a prototypical zeolitic imidazolate framework (ZIF-8) along two modes of mechanical failure in response to tensile and shear forces using first-principles simulations. Our generalized stacking fault energy surface reveals an intrinsic stacking fault of surprisingly low energy comparable to that in copper, though the energy barrier associated with its formation is much higher. The lack of vibrational spectroscopic evidence for such faults in experiments can be explained with the structural instability of the barrier state to form a denser and disordered state of ZIF-8 seen in our analysis, that is, large shear leads to its amorphization rather than formation of faults.
authors.affiliation: Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 064, India.
authors.forename: Vinay I
authors.initials: VI
authors.lastname: Hegde
authors.affiliation: Department of Engineering Science, University of Oxford , Parks Road, Oxford OX1 3PJ, United Kingdom.
authors.forename: Jin-Chong
authors.initials: JC
authors.lastname: Tan
authors.affiliation: Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 064, India.
authors.forename: Umesh V
authors.initials: UV
authors.lastname: Waghmare
authors.affiliation: Department of Materials Science and Metallurgy, University of Cambridge , Pembroke Street, Cambridge CB2 3QZ, United Kingdom.
authors.forename: Anthony K
authors.initials: AK
authors.lastname: Cheetham
keywords: amorphization; mechanical behavior; phonons; surface energy; zeolitic imidazolate frameworks (ZIFs); γ-surface