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dc.contributor.advisorBaykara, Mehmet Zeyyaden_US
dc.contributor.authorÖzoğul, Alperen_US
dc.date.accessioned2017-05-24T10:57:02Z
dc.date.available2017-05-24T10:57:02Z
dc.date.copyright2017-05
dc.date.issued2017-05
dc.date.submitted2017-05-17
dc.identifier.urihttp://hdl.handle.net/11693/32992
dc.descriptionCataloged from PDF version of article.en_US
dc.descriptionThesis (M.S.): Bilkent University, Department of Mechanical Engineering, İhsan Doğramacı Bilkent University, 2017.en_US
dc.descriptionIncludes bibliographical references (leaves 54-58).en_US
dc.description.abstractStructural lubricity describes a state of ultra-low friction involving relative motion between atomically flat and molecularly clean surfaces with incommensurate structures. While the occurrence of structural lubricity was quantitatively confirmed under ultrahigh vacuum (UHV) conditions first, recently reported experiments have demonstrated that structurally lubric sliding is achievable under ambient conditions as well, specifically at mesoscopic interfaces formed between thermally deposited gold nanoparticles and graphite. The question that is covered in this thesis is whether the observation of structural lubricity under ambient conditions is limited solely to gold nanoparticles. To answer this question, an investigation of the frictional behavior of platinum nanoparticles laterally manipulated on graphite has been conducted. In particular, platinum nanoparticles have been prepared by e-beam evaporation of a thin film of platinum on graphite, followed by post-deposition annealing. Morphological characterization of the particles was performed via scanning electron microscopy (SEM) and transmission electron microscopy (TEM), revealing a crystalline structure. X-Ray photoelectron spectroscopy (XPS) revealed no significant change in the electronic structure of platinum upon exposure to air, ruling out the oxidation of platinum nanoparticles under ambient conditions. This finding was supported by cross-sectional TEM measurements demonstrating the absence of an oxide layer on the particle surfaces. Lateral manipulation experiments have been performed on platinum nanoparticles of mesoscopic dimensions (4000 − 75,000 nm2) under ambient conditions via atomic force microscopy (AFM), whereby results indicated the occurrence of structural lubricity, although with a higher magnitude of friction forces when compared with gold nanoparticles. Thus, it is confirmed that the occurrence of structural lubricity between incommensurate, atomically flat surfaces should be independent of material choice, as stated in the theory. Lastly, an attempt has been made to alter the structure and chemistry of the sliding surface of platinum nanoparticles. For this purpose, platinum nanoparticles have been oxidised in a reactive oxygen plasma atmosphere. XPS results confirmed the existence of oxidised platinum, and structural characterization performed by SEM showed that there was no significant change in morphology. Lateral manipulation experiments performed on oxidised platinum nanoparticles showed that these nanoparticles experience approximately two times as much friction as platinum nanoparticles. The potential reasons behind this observation are discussed.en_US
dc.description.statementofresponsibilityby Alper Özoğul.en_US
dc.format.extentxv, 58 leaves : charts (some color) ; 29 cmen_US
dc.language.isoEnglishen_US
dc.rightsinfo:eu-repo/semantics/openAccessen_US
dc.subjectStructural Lubricityen_US
dc.subjectSuperlubricityen_US
dc.subjectNanotribologyen_US
dc.subjectNanoparticlesen_US
dc.subjectAtomic Force Microscopyen_US
dc.subjectFriction Force Microscopyen_US
dc.titleInvestigation of structural lubricity on platinum nanoparticles under ambient conditionsen_US
dc.title.alternativePlatin nanoparçacıkların ortam koşullarında yapısal kayganlığının araştırılmasıen_US
dc.typeThesisen_US
dc.departmentDepartment of Mechanical Engineeringen_US
dc.publisherBilkent Universityen_US
dc.description.degreeM.S.en_US
dc.identifier.itemidB155529


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