Banca de DEFESA: AMANDA INGRID DOS SANTOS BARBOSA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : AMANDA INGRID DOS SANTOS BARBOSA
DATE: 03/03/2022
TIME: 14:00
LOCAL: Instituto de Física (remoto)
TITLE:

Theoretical-Experimental StudyofOptical and Structural Properties of Pure and Doped Titanium Dioxide Nanocrystals with Manganese Ions

KEY WORDS:

Nanocrystals, TitaniumDioxide, TransitionMetals, Manganese, ConcentrationEffect, Doping, X-Ray Diffraction, Raman Spectroscopy, Scanning Electron Microscopy, Optical Absorption, Crystal Field Theory

PAGES: 90
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUMMARY:

Titaniumdioxide (TiO₂) is a semiconductorthatpresentsabsorptionandemission in the ultravioletregion, photostability, catalyticandosseointegratingpropertiesthatallow its use in varioustechnologicaland medical applications, such as catalysts, photovoltaic devices andosseointegratingagents. The incorporationoftransition metal ions (MT) in semiconductorsgenerates magneto-opticalpropertiesthatcanbetuned as a functionof the dopantconcentration. Fewworks in the literaturestudy the structural, opticalandmorphologicalpropertiesof MT-doped TiO₂. Therefore, in ordertounderstandhow the physicalandchemicalpropertiescanbeinfluenced as a functionof the dopantconcentration, in thisworkwesynthesizedandcharacterizednanocrystals (NCs) of TiO₂dopedwithincreasingconcentrationsofmanganeseions (Mn⁺²) by the methodofchemicalprecipitation. Structuralpropertieswereinvestigatedusing X-Ray Diffraction (XRD) and Raman Spectroscopy. OpticalpropertieswereinvestigatedusingOpticalAbsorptionSpectroscopy (AO) andapplicationof the Crystal Field Theory (CCT) model. The morphologicalpropertieswereinvestigatedusingScanningElectronMicroscopy (SEM). In the XRD and Raman spectradiffractionpatterns, the XRD diffractionpatternsand the bands correspondingto the characteristicvibrationalmodesof TiO₂NCs in the anatasephasewereobserved, respectively, notbeingalteredwith the doping concentration. In the AO spectra, the absorption band characteristicof TiO₂NCswasobservedandthatwithincreasing doping therewas a red shift, whichisrelatedto the strongsp-d exchangeinteraction, confirming the incorporationof Mn2+ ions in the NCs. of TiO₂. In the applicationof TCC andwith the aidofTanabe-Suganodiagrams, it wasshownthat Mn²⁺ionsweresubstituted for thoseof Ti⁴⁺ in tetrahedralandoctahedral sites of TiO₂nanocrystals, dependingon the doping concentration. Therefore, basedontheseresults, the successfulgrowthofpureand Mn²⁺-doped TiO₂NCs in the anatasephasewasconfirmedandthat, dependingon the concentration, it ispossibleto tune the site where the Mn²⁺ions are, stronglyaltering the opticalproperties.

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