scholarly journals Unraveling the Core–Shell Structure of Ligand-Capped Sn/SnOxNanoparticles by Surface-Enhanced Nuclear Magnetic Resonance, Mössbauer, and X-ray Absorption Spectroscopies

ACS Nano ◽  
2014 ◽  
Vol 8 (3) ◽  
pp. 2639-2648 ◽  
Author(s):  
Loredana Protesescu ◽  
Aaron J. Rossini ◽  
Dominik Kriegner ◽  
Maxence Valla ◽  
Antoine de Kergommeaux ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Shell Structure ◽  
Core Shell ◽  
X Ray ◽  
The Core ◽  
Surface Enhanced ◽  
Core Shell Structure ◽  
X Ray Absorption ◽  
Nuclear Magnetic

scholarly journals The Core/Shell Structure of CdSe/ZnS Quantum Dots Characterized by X-Ray Absorption Fine Spectroscopy

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Huijing Wei ◽  
Jing Zhou ◽  
Linjuan Zhang ◽  
Fang Wang ◽  
Jianqiang Wang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Shell Structure ◽  
Single Step ◽  
Organic Sulfur ◽  
Core Shell ◽  
X Ray ◽  
The Core ◽  
Absorption Fine ◽  
Core Shell Structure ◽  
X Ray Absorption

Understanding the chemical and physical properties of core/shell nanocrystal quantum dots (QDs) is key for their use in light-emission applications. In this paper, a single-step injection-free scalable synthetic method is applied to prepare high-quality core/shell QDs with emission wavelengths of 544 nm, 601 nm, and 634 nm. X-ray absorption fine structure spectra are used to determine the core/shell structure of CdSe/ZnS quantum dots. Moreover, theoretical XANES spectra calculated by FEFF.8.20 are used to determine the structure of Se and S compounds. The QD samples displayed nearly spherical shapes with diameters of approximately 3.4 ± 0.5 nm (634 nm), 4.5 ± 0.4 nm (601 nm), and 5.5 ± 0.5 nm (544 nm). With XANES results and MS calculations, it is indicated that sphalerite ZnS capped with organic sulfur ligands should be the shell structure. Wurtzite CdSe is the main core structure with a Cd-Se bond length of 2.3 Å without phase shift. This means that different emission wavelengths are only due to the crystal size with single-step injection-free synthesis. Therefore, single-step injection-free synthesis could generate a nearly ideal core/shell structure of CdSe/ZnS QDs capped with an organic sulfur ligand.

Controlled Synthesis of Core-Shell Structure SiO2 /NaGdF4:Eu3+ Magnetic and Optical Bifunctional Composite

2014 ◽  
Vol 936 ◽  
pp. 359-363
Author(s):  
Yan Li Wu ◽  
Min Liao ◽  
Hai Xin Ding ◽  
Ru Chun Yang ◽  
Dan Dan Xiong ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Shell Structure ◽  
Photo Luminescence ◽  
Core Shell ◽  
Controlled Synthesis ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Core ◽  
Core Shell Structure ◽  
Shell Composite

The SiO2/NaGdF4:Eu3+ core/shell composite was prepared by a template-mediated method, making monodispersed SiO2 as core and NaGdF4:Eu colloids as shell, the morphology and the core-shell structure of the resulting particles were analyzed by SEM,X-ray diffraction, and the photo-luminescence and magnetic properties of the microspheres were investigated too. The results shows the composite have great potential to be used as homogeneous magnetic/optical bifunctional material.

Microstructure and electronic behavior of PtPd@Pt core-shell nanowires

2010 ◽  
Vol 25 (4) ◽  
pp. 711-717 ◽  
Author(s):  
Wei-Qiang Han ◽  
Dong Su ◽  
Michael Murphy ◽  
Matthew Ward ◽  
Tsun-Kong Sham ◽  
...  
Keyword(s):  
Shell Structure ◽  
Phase Transfer ◽  
Core Shell ◽  
Face Centered Cubic ◽  
Edge Structure ◽  
X Ray ◽  
One Step ◽  
Core Shell Structure ◽  
Face Centered ◽  
X Ray Absorption

PtPd@Pt core-shell ultrathin nanowires were prepared using a one-step phase-transfer approach. The diameters of the nanowires range from 2 to 3 nm, and their lengths are up to hundreds of nanometers. Line scanning electron energy loss spectra showed that PtPd bimetallic nanowires have a core-shell structure, with a PtPd alloy core and a Pt monolayer shell. X-ray absorption near edge structure (XANES) spectra reveal that a strong Pt-Pd interaction exists in this nanowire system in that there is PtPd alloying and/or interfacial interaction. Extended x-ray absorption fine structures (EXAFS) further confirms the PtPd@Pt core-shell structure. The bimetallic nanowires were determined to be face-centered cubic structures. The long-chain organic molecules of n-dodecyl trimethylammonium bromide and octadecylamine, used as surfactants during synthesis, were clearly observed using aberration-corrected TEM operated at 80 KV. The interaction of Pt and surfactants was also revealed by EXAFS.

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