Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/31617
Title: Cu AND Mn EMBEDDED-ZnO NANOCLUSTER ASSEMBLED FILMS AND NANOCOMPOSITES: FABRICATION, CHARACTERIZATION AND PROPERTIES
Authors: TOH CHEN CHIN
Keywords: Cu,Mn,ZnO,Nanoclusters,Nanocluster Assembled Films,Nanocomposites
Issue Date: 28-Sep-2011
Source: TOH CHEN CHIN (2011-09-28). Cu AND Mn EMBEDDED-ZnO NANOCLUSTER ASSEMBLED FILMS AND NANOCOMPOSITES: FABRICATION, CHARACTERIZATION AND PROPERTIES. ScholarBank@NUS Repository.
Abstract: In this Master Thesis, Cu and Mn nanoclusters were embedded in ZnO in the form of nanocluster assembled films (without matrix) and nanocomposites (with SiO2 matrix) in order to investigate magnetism of non-ferromagnetic nanoclusters in the environment of insulating diluted magnetic semiconductor oxide system. Transition metals nanoclusters such as Cu and Mn do not contribute to the ferromagnetism of samples were embedded in ZnO thin films. Both transition metals and their secondary phases are non-ferromagnetic phases due to fully-occupied d-orbitals or fully-filled majority-spin states. Detailed analysis of microstructural,chemical, magnetism and optical properties of nanoclusters assembled films and nanocomposites have been conducted. Room temperature ferromagnetism can be induced in Cu embedded-ZnO thin films as suggested by small coercivities of their M-H curves. From XRD and TEM results, no substitution of Cu and Mn nanoclusters over Zn cation site was detected, instead they were surrounded by Zn and O atoms to form nanocluster-matrix interface. XRD and high resolution TEM and SADP analysis excluded the possibility of presence of ferromagnetic phases in the samples. The XPS result suggests Cu in the +1 valence state is the most favorable condition for the occurrence of ferromagnetism. Through comparison of Cu and Cu-oxides embedded SiO2 system with Cu and Cu-oxides embedded ZnO system, the interaction of nanoclusters with their environment was proved to be important for the enhanced ferromagnetism. However, PL (photoluminescence) analysis indicated the presence of oxygen vacancies greatly enhanced the Ms value of samples.On the other hand, Raman spectra of ZnO:Mn nanoclusters system shows contribution of Mn3+-Mn4+ double exchange interactions in enhancing the ferromagnetism of nanocomposites.In conclusion, the defect-mediated room temperature ferromagnetism was thought responsible for the enhanced ferromagnetic behavior in the Zn0.94Cu0.06O nanocluster assembled films, ZnO:Cu-SiO2 nanocomposite, Zn0.94Mn0.06O nanocluster assembled films and ZnO:Mn-SiO2 nanocomposite.
URI: http://scholarbank.nus.edu.sg/handle/10635/31617
Appears in Collections:Master's Theses (Open)

Show full item record
Files in This Item:
File Description SizeFormatAccess SettingsVersion 
TohChenChin.pdf5 MBAdobe PDF

OPEN

NoneView/Download

Page view(s)

296
checked on Dec 11, 2017

Download(s)

461
checked on Dec 11, 2017

Google ScholarTM

Check


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.