In Situ Atomic-Scale Observation of Surface-Tension-Induced Structural Transformation of Ag-NiPx Core–Shell Nanocrystals

ACS Nano ◽  
2018 ◽  
Vol 12 (7) ◽  
pp. 7197-7205 ◽  
Author(s):  
Xing Huang ◽  
Zhongqiang Liu ◽  
Marie-Mathilde Millet ◽  
Jichen Dong ◽  
Milivoj Plodine ◽  
...  
Keyword(s):  
Surface Tension ◽  
Structural Transformation ◽  
Atomic Scale ◽  
Core Shell

scholarly journals In-situ observation of Cu-Pt core-shell nanoparticles in the atomic scale by XAFS

2013 ◽  
Vol 430 ◽  
pp. 012038 ◽  
Author(s):  
Xusheng Zheng ◽  
Shoujie Liu ◽  
Xing Chen ◽  
Jie Cheng ◽  
Qing Ye ◽  
...  
Keyword(s):  
Atomic Scale ◽  
Core Shell ◽  
In Situ Observation ◽  
Shell Nanoparticles ◽  
Core Shell Nanoparticles

scholarly journals In situ atomic-scale observation of oxygen-driven core-shell formation in Pt3Co nanoparticles

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Sheng Dai ◽  
Yuan You ◽  
Shuyi Zhang ◽  
Wei Cai ◽  
Mingjie Xu ◽  
...  
Keyword(s):  
Atomic Scale ◽  
Core Shell ◽  
Shell Formation

High-Temperature Synthesis of CdSe-Based Core/Shell, Core/Shell/Shell, and Core/Graded-Shell Nanoplatelets for Stable and Efficient Narrowband Emitters

2019 ◽  
Author(s):  
Aurelio A. Rossinelli ◽  
Henar Rojo ◽  
Aniket S. Mule ◽  
Marianne Aellen ◽  
Ario Cocina ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Temperature ◽  
Equilibrium Shape ◽  
Size Variation ◽  
Crystal Defects ◽  
Atomic Scale ◽  
Quantum Yields ◽  
Core Shell ◽  
Compositional Gradient ◽  
High Quality

<div>Colloidal semiconductor nanoplatelets exhibit exceptionally narrow photoluminescence spectra. This occurs because samples can be synthesized in which all nanoplatelets share the same atomic-scale thickness. As this dimension sets the emission wavelength, inhomogeneous linewidth broadening due to size variation, which is always present in samples of quasi-spherical nanocrystals (quantum dots), is essentially eliminated. Nanoplatelets thus offer improved, spectrally pure emitters for various applications. Unfortunately, due to their non-equilibrium shape, nanoplatelets also suffer from low photo-, chemical, and thermal stability, which limits their use. Moreover, their poor stability hampers the development of efficient synthesis protocols for adding high-quality protective inorganic shells, which are well known to improve the performance of quantum dots. <br></div><div>Herein, we report a general synthesis approach to highly emissive and stable core/shell nanoplatelets with various shell compositions, including CdSe/ZnS, CdSe/CdS/ZnS, CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S, and CdSe/ZnSe. Motivated by previous work on quantum dots, we find that slow, high-temperature growth of shells containing a compositional gradient reduces strain-induced crystal defects and minimizes the emission linewidth while maintaining good surface passivation and nanocrystal uniformity. Indeed, our best core/shell nanoplatelets (CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S) show photoluminescence quantum yields of 90% with linewidths as low as 56 meV (19.5 nm at 655 nm). To confirm the high quality of our different core/shell nanoplatelets for a specific application, we demonstrate their use as gain media in low-threshold ring lasers. More generally, the ability of our synthesis protocol to engineer high-quality shells can help further improve nanoplatelets for optoelectronic devices.</div>

scholarly journals In-situ Electrochemical Synthesis of Core-shell Structural NbC@Nb5Si3/Nb Composites in Molten Salt

2021 ◽  
Vol 714 (3) ◽  
pp. 032008
Author(s):  
Hongmei Li ◽  
Zhisheng Nong ◽  
Qian Xu ◽  
Qiushi Song ◽  
Ying Chen ◽  
...  
Keyword(s):  
Molten Salt ◽  
Electrochemical Synthesis ◽  
Core Shell

scholarly journals In Situ Observation of Electron-Beam-Induced Formation of Nano-Structures in PbTe

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 163
Author(s):  
Iryna Zelenina ◽  
Igor Veremchuk ◽  
Yuri Grin ◽  
Paul Simon
Keyword(s):  
Electron Beam ◽  
Gas Phase ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Atomic Scale ◽  
In Situ Observation ◽  
Nano Structures ◽  
Transmission Electron ◽  
Initial Crystal

Nano-scaled thermoelectric materials attract significant interest due to their improved physical properties as compared to bulk materials. Well-shaped nanoparticles such as nano-bars and nano-cubes were observed in the known thermoelectric material PbTe. Their extended two-dimensional nano-layer arrangements form directly in situ through electron-beam treatment in the transmission electron microscope. The experiments show the atomistic depletion mechanism of the initial crystal and the recrystallization of PbTe nanoparticles out of the microparticles due to the local atomic-scale transport via the gas phase beyond a threshold current density of the beam.

scholarly journals Morphology Controlled Synthesis of γ-Al2O3 Nano-Crystallites in Al@Al2O3 Core–Shell Micro-Architectures by Interfacial Hydrothermal Reactions of Al Metal Substrates

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 310
Author(s):  
Dohyeon Han ◽  
Doohwan Lee
Keyword(s):  
Electrostatic Interactions ◽  
Heterogeneous Catalysts ◽  
Metal Substrate ◽  
Inorganic Anions ◽  
Core Shell ◽  
Hydroxyl Groups ◽  
Hydrothermal Reactions ◽  
Fine Control ◽  
Reaction Processes

Fine control of morphology and exposed crystal facets of porous γ-Al2O3 is of significant importance in many application areas such as functional nanomaterials and heterogeneous catalysts. Herein, a morphology controlled in situ synthesis of Al@Al2O3 core–shell architecture consisting of an Al metal core and a porous γ-Al2O3 shell is explored based on interfacial hydrothermal reactions of an Al metal substrate in aqueous solutions of inorganic anions. It was found that the morphology and structure of boehmite (γ-AlOOH) nano-crystallites grown at the Al-metal/solution interface exhibit significant dependence on temperature, type of inorganic anions (Cl−, NO3−, and SO42−), and acid–base environment of the synthesis solution. Different extents of the electrostatic interactions between the protonated hydroxyl groups on (010) and (001) facets of γ-AlOOH and the inorganic anions (Cl−, NO3−, SO42−) appear to result in the preferential growth of γ-AlOOH toward specific crystallographic directions due to the selective capping of the facets by adsorption of the anions. It is hypothesized that the unique Al@Al2O3 core–shell architecture with controlled morphology and exposed crystal-facets of the γ-Al2O3 shell can provide significant intrinsic catalytic properties with enhanced heat and mass transport to heterogeneous catalysts for applications in many thermochemical reaction processes. The direct fabrication of γ-Al2O3 nano-crystallites from Al metal substrate with in-situ modulation of their morphologies and structures into 1D, 2D, and 3D nano-architectures explored in this work is unique and can offer significant opportunities over the conventional methods.

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