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Atomic-Scale Study Of Complex Cobalt Oxide Using Scanning Transmission Electron Microscope

thesis
posted on 22.07.2017 by Ahmet Gulec
Cobalt oxides offer a rich field for the formation of novel phases, including superconductors and exotic magnetic phases, involving a mixed valence state for cobalt and/or the presence of oxygen vacancies. Having spin states, such as, low spin (LS), high spin (HS), and intermediate spin (IS), cobalt oxides differ from other 3d metal oxides The presence of such spin states make the physics of the cobalt oxides so complicated that it has not yet been completely understood. In order to improve our understanding of the various phase transitions observed in Cobalt oxides and to comprehend the relationship between crystal and electronic structure, both high energy resolution and high spatial resolution are essential. Fortunately, transmission electron microscopy (TEM) is a technique which is capable of fulfilling both of these requirements. In this thesis, I have utilized unique techniques in a scanning transmission electron microscope (STEM) to analyze the atomic-scale structure-property relationship, both at room temperature and through insitu cooling to liquid nitrogen (LN2) temperature. In particular, by using correlated Z-contrast imaging, electron energy loss spectrum (EELS) and electron energy loss magnetic circular dichroism (EMCD), the structure, composition, bonding and magnetic behavior are characterized directly on the atomic scale.

History

Advisor

Klie, Robert F.

Department

Physics

Degree Grantor

University of Illinois at Chicago

Degree Level

Doctoral

Committee Member

Öğüt, Serdar Schroeder, Andreas w. Nicholls, Alan W. Takoudis, Christos G.

Submitted date

2015-05

Language

en

Issue date

21/07/2015

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