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dc.contributor.authorERKARTAL, MUSTAFA
dc.date.accessioned2020-07-22T11:53:06Z
dc.date.available2020-07-22T11:53:06Z
dc.date.issued2019en_US
dc.identifier.otherTez No: 609394
dc.identifier.urihttps://hdl.handle.net/20.500.12573/338
dc.description.abstractThe aim of this PhD dissertation is to investigate the behavior of different MOFs under hydrostatic and uniaxial stresses by using ab-inito molecular dynamics simulations (AIMD). The results obtained from computations are reported in three main chapters. In the first part, ab initio simulations within a generalized gradient approximation (GGA) were carried out to investigate the response of MOF-5 to high pressure. Similar to the previous experimental findings, a pressure-induced amorphization (PIA) was observed at 2 GPa through the simulations. The phase transformation was an irreversible first order transition and accompanied by a volume collapse around 68%. Remarkably, the transition arose from local distortions and contrary to previous suggestions, did not involve any bond breaking or formation. Additionally, a drastic band gap closure was perceived for the amorphous state. For the second part of this project, AIMD simulations were performed to probe the high-pressure behavior of ZIF-8 over wide pressure-range. Under compression, the enormous distortions in the ZnN4 tetrahedral units led to a crystal-to-amorphous phase transition at around 3?GPa. During the amorphization process, the Zn-N coordination was retained. No other phase change but a possible fracture of the system was proposed above 10?GPa. When the applied pressure was released just before the amorphization, the rotations of imidazolate linkers (swing effect) caused an isostructural crystal-to-crystal phase transition. In the tensile regime, no phase transition was perceived up to -2.75?GPa?at which point the structural failure was observed. In the last part of this research project, the phase transitions of ZIF polymorphs (ZIF-1 to ZIF-3) under pressure were comprehensively simulated. ZIF-1 showed some consecutive crystal-crystal and crystal-amorphous phase transitions between -2 GPa (tension) and 10 GPa (compression). On the other hand, ZIF-2 and ZIF- 3 presented similar pressure-volume relation in both tension and compression regions. In compression region, a rapid crystal-amorphous at relatively lower compression regime and most likely an amorphous-amorphous transition were explored whereas the structural failure was observed at around -3 GPa for all ZIFs.en_US
dc.language.isoengen_US
dc.publisherAbdullah Gül Üniversitesien_US
dc.rightsinfo:eu-repo/semantics/openAccessen_US
dc.subjectMetal-Organic Frameworks (MOFs)en_US
dc.subjectPressure-Induced Amorphization (PIA)en_US
dc.subjectAb Initio Molecular Dynamics (AIMD)en_US
dc.subjectAmorphousen_US
dc.titleModelling and investigations of amorphous materialsen_US
dc.title.alternativeAmorf malzemelerin modellenmesi ve incelenmesien_US
dc.typedoctoralThesisen_US
dc.contributor.departmentAGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümüen_US
dc.contributor.institutionauthorERKARTAL, MUSTAFA
dc.relation.publicationcategoryTezen_US


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