Synthesis, characterization and pore size control of mesoporous li4ti5o12, cotio3 and mntio3 thin films

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buir.advisorDağ, Ömer
dc.contributor.authorAvcı, Civan
dc.date.accessioned2016-04-18T08:14:51Z
dc.date.available2016-04-18T08:14:51Z
dc.date.copyright2014-07
dc.date.issued2014-07
dc.date.submitted07-08-2014
dc.departmentDepartment of Chemistryen_US
dc.descriptionCataloged from PDF version of thesis.en_US
dc.descriptionIncludes bibliographical references (leaves 106-113).en_US
dc.descriptionThesis (M.S.): Bilkent University, The Department of Chemistry and the Graduate School of Engineering and Science, 2014.en_US
dc.description.abstractSalt-surfactant lyotropic liquid crystalline mesophases can be used to produce mesoporous highly transparent thin films of metal titanates. In this study, the salt-surfactant assembly is described as molten salt assisted self-assembly (MASA) process that was optimized for the synthesis of mesoporous CoTiO3, MnTiO3 and Li4Ti5O12 thin films with high specific surface area and narrow pore size distribution.The materials have been characterized using x-ray diffraction (XRD), Raman and UV-Visible absorption spectroscopy, Transmission Electron Microscopy (TEM), and nitrogen adsorption/desorption techniques. An initial clear solution containing two different surfactants (C12H25(OCH2CH2)10OH, C12EO10, and C16H33N(CH3)3Br, CTAB), nitrate salt ([Co(H2O)6](NO3)2 or [Mn(H2O)6](NO3)2 or LiNO3) of the convenient metal, titanium(IV)butoxide (Ti(OC4H9)4, TTB) as titania source and ethanol as solvent is prepared at an appropriate pH. Spin or spray coating methods was employed to coat the substrates using above solutions. During the coating process, a liquid crystalline mesophase is formed instantaneously upon the evaporation of the solvent. The hydrophilic surfactant domains guide the molten salt and hydrolysis products of TTB to form a three dimensional porous network throughout the film. The synthesis is completed with a fast calcination step (10-20 min) at temperatures ranging between 350 oC to 550 oC. Mesoporous CoTiO3, MnTiO3 and Li4Ti5O12 display uniform pores with a pore size of 25 to 55 Å, surface area of 193 to 445 m2/g and pore volume of 0.17 to 0.43 cm3/g depending on the composition and synthesis conditions. The surface area, pore-size, pore-wall thickness, pore volume and crystallinity of the pore-walls can be controlled by simply controlling the calcination or annealing steps of the process without damaging the mesoporous network. The films, produced by employing the MASA approach, are optically transparent and exhibit good adhesion on commonly used substrates (glass, silicon, aluminum… etc.). Both CoTiO3 and MnTiO3 are semi crystalline at low temperatures and undergo segregation into metal oxide and titania above 500 oC. However, Li4Ti5O12 is nanocrystalline even at 350 oC and stable up to 550 oC. The initial calcination temperature and duration are two important parameters to further control the pore and crystallinity related properties in all three titanates. The counter anion of the salt also plays an important role to adjust the porosity and to further modify. In this investigation, we also used the bromide salt of cobalt(II) and found out that one can incorporate graphitic carbon into mesoporous network. The MASA process, that is further expanded in this work, is not limited to metal titanates, investigated in this work and previous works; it is a general and new synthetic route to produce many other mesoporous metal oxides as powders, as well as thin films, such as LiCoO2, LiMn2O4, etc…en_US
dc.description.degreeM.S.en_US
dc.description.statementofresponsibilityby Civan Avcı.en_US
dc.format.extent113 leaves : illustrations, graphics.en_US
dc.identifier.itemidB147899
dc.identifier.urihttp://hdl.handle.net/11693/28920
dc.language.isoEnglishen_US
dc.publisherBilkent Universityen_US
dc.rightsinfo:eu-repo/semantics/openAccessen_US
dc.subjectCoTiO3en_US
dc.subjectMnTiO3en_US
dc.subjectLi4Ti5O12en_US
dc.subjectMesoporous thin filmsen_US
dc.subjectMASA synthesisen_US
dc.titleSynthesis, characterization and pore size control of mesoporous li4ti5o12, cotio3 and mntio3 thin filmsen_US
dc.title.alternativeMezogözenekli Li4Ti5O12, CoTiO3 ve MnTiO3 ince filmlerin sentezi, karakterizasyonu ve gözenek boyutu kontrolüen_US
dc.typeThesisen_US

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