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Title: Core–Shell to Doped Quantum Dots: Evolution of the Local Environment Using XAFS

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 Fe 3O 4 core with CdS using X-ray absorption spectroscopy. The data reveals that Fe 3O 4 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.

Authors:
; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1324809
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry. C; Journal Volume: 120; Journal Issue: 33
Country of Publication:
United States
Language:
ENGLISH
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Saha, Avijit, Chattopadhyay, Soma, Shibata, Tomohiro, and Viswanatha, Ranjani. Core–Shell to Doped Quantum Dots: Evolution of the Local Environment Using XAFS. United States: N. p., 2016. Web. doi:10.1021/acs.jpcc.6b06803.
Saha, Avijit, Chattopadhyay, Soma, Shibata, Tomohiro, & Viswanatha, Ranjani. Core–Shell to Doped Quantum Dots: Evolution of the Local Environment Using XAFS. United States. doi:10.1021/acs.jpcc.6b06803.
Saha, Avijit, Chattopadhyay, Soma, Shibata, Tomohiro, and Viswanatha, Ranjani. Fri . "Core–Shell to Doped Quantum Dots: Evolution of the Local Environment Using XAFS". United States. doi:10.1021/acs.jpcc.6b06803.
@article{osti_1324809,
title = {Core–Shell to Doped Quantum Dots: Evolution of the Local Environment Using XAFS},
author = {Saha, Avijit and Chattopadhyay, Soma and Shibata, Tomohiro and Viswanatha, Ranjani},
abstractNote = {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.},
doi = {10.1021/acs.jpcc.6b06803},
journal = {Journal of Physical Chemistry. C},
number = 33,
volume = 120,
place = {United States},
year = {Fri Sep 30 00:00:00 EDT 2016},
month = {Fri Sep 30 00:00:00 EDT 2016}
}