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Title: Core-Shell to Doped Quantum Dots: Evolution of the Local Environment Using XAFS
Authors: Saha, Avijit
Chattopadhyay, Soma
Shibata, Tomohiro
Viswanatha, Ranjani
Keywords: Chemistry
Materials Science
Doping Semiconductor Nanocrystals
Magnetic Semiconductor
Issue Date: 2016
Publisher: American Chemical Society
Citation: Saha, A.; Chattopadhyay, S.; Shibata, T.; Viswanatha, R., Core-Shell to Doped Quantum Dots: Evolution of the Local Environment Using XAFS. Journal of Physical Chemistry C 2016, 120 (33), 18945-18951
Journal of Physical Chemistry C
Abstract: Internal structure study at an atomic level is a challenging task with far reaching consequences to its material properties, specifically in the field of transition metal doping in quantum dots. Diffusion of transition metal ions in and out of quantum dots forming magnetic clusters has been a major bottleneck in this class of materials. Diffusion of the magnetic ions from the core into the nonmagnetic shell in a core/shell heterostructure architecture to attain uniform doping has been recently introduced and yet to be understood. In this work, we have studied the local structure variation of Fe as a function of CdS matrix thickness and annealing time during the overcoating of Fe3O4 core with CdS using X-ray absorption spectroscopy. The data reveals that Fe3O4 core initially forms a core/shell structure with CdS followed by alloying at the interface eventually completely diffusing all the way through the CdS matrix to form homogeneously Fe-doped CdS QDs with excellent control over size and size distribution. Study of Fe K-edge shows a complete change of Fe local environment from Fe-O to FeS.
Description: Restricted Access
ISSN: 1932-7447
Appears in Collections:Research Papers (Ranjani Viswanatha)

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