scholarly journals Dominant Polar Surfaces of Colloidal II–VI Wurtzite Semiconductor Nanocrystals Enabled by Cation Exchange

2020 ◽  
Vol 11 (13) ◽  
pp. 4990-4997
Author(s):  
Aixiang Wang ◽  
Wenjie Wang ◽  
Jiayi Chen ◽  
Rundong Mao ◽  
Yingping Pang ◽  
...  
Keyword(s):  
Cation Exchange ◽  
Semiconductor Nanocrystals ◽  
Polar Surfaces

Controllable conversion of plasmonic Cu2−xS nanoparticles to Au2S by cation exchange and electron beam induced transformation of Cu2−xS–Au2S core/shell nanostructures

Nanoscale ◽  
2014 ◽  
Vol 6 (15) ◽  
pp. 8852-8857 ◽  
Author(s):  
Xianliang Wang ◽  
Xin Liu ◽  
Dewei Zhu ◽  
Mark T. Swihart
Keyword(s):  
Electron Beam ◽  
Cation Exchange ◽  
Semiconductor Nanocrystals ◽  
Core Shell ◽  
Shell Nanostructures

Self-doped Cu2−xS plasmonic semiconductor nanocrystals were converted into monodisperse Cu2−xS–Au2S nanocrystals of tunable composition, including pure Au2S, by cation exchange.

scholarly journals Mechanistic insight into copper cation exchange in cadmium selenide semiconductor nanocrystals using X-ray absorption spectroscopy

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Alex Khammang ◽  
Joshua T. Wright ◽  
Robert W. Meulenberg
Keyword(s):  
Cation Exchange ◽  
Absorption Spectroscopy ◽  
Cooperative Behavior ◽  
Semiconductor Nanocrystals ◽  
Copper Cation ◽  
Energy Materials ◽  
X Ray ◽  
Data Points ◽  
X Ray Absorption

AbstractIn terms of producing new advances in sustainable nanomaterials, cation exchange (CE) of post-processed colloidal nanocrystals (NCs) has opened new avenues towards producing non-toxic energy materials via simple chemical techniques. The main processes governing CE can be explained by considering hard/soft acid/base theory, but the detailed mechanism of CE, however, has been debated and has been attributed to both diffusion and vacancy processes. In this work, we have performed in situ x-ray absorption spectroscopy to further understand the mechanism of the CE of copper in solution phase CdSe NCs. The x-ray data indicates clear isosbestic points, suggestive of cooperative behavior as previously observed via optical spectroscopy. Examination of the extended x-ray absorption fine structure data points to the observation of interstitial impurities during the initial stages of CE, suggesting the diffusion process is the fundamental mechanism of CE in this system.

scholarly journals Explaining the Unusual Photoluminescence of Semiconductor Nanocrystals Doped via Cation Exchange

Nano Letters ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 4797-4803 ◽  
Author(s):  
Abigail R. Freyer ◽  
Peter C. Sercel ◽  
Zhentao Hou ◽  
Benjamin H. Savitzky ◽  
Lena F. Kourkoutis ◽  
...  
Keyword(s):  
Cation Exchange ◽  
Semiconductor Nanocrystals

Modulating Ferroelectric Response in Colloidal Semiconductor Nanocrystals through Cation Exchange

2019 ◽  
Vol 31 (11) ◽  
pp. 4275-4281 ◽  
Author(s):  
Cara E. Bradsher ◽  
James R. McBride ◽  
Janet E. Macdonald ◽  
Sandra J. Rosenthal
Keyword(s):  
Cation Exchange ◽  
Semiconductor Nanocrystals ◽  
Colloidal Semiconductor Nanocrystals ◽  
Colloidal Semiconductor

On the Faceting of Polar Ceramic Surfaces: Microscopy and Holography Studies of MGO(111) Surfaces

1996 ◽  
Vol 54 ◽  
pp. 366-367
Author(s):  
M. Gajdardziska-Josifovska ◽  
B. G. Frost ◽  
E. Völkl ◽  
L. F. Allard
Keyword(s):  
Electron Microscopy ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Electron Holography ◽  
Flat Surfaces ◽  
Transmission Electron ◽  
Excess Surface ◽  
Polar Surfaces ◽  
Salt Structure ◽  
Crystallographic Planes

Polar surfaces are those crystallographic faces of ionically bonded solids which, when bulk terminated, have excess surface charge and a non-zero dipole moment perpendicular to the surface. In the case of crystals with a rock salt structure, {111} faces are the exemplary polar surfaces. It is commonly believed that such polar surfaces facet into neutral crystallographic planes to minimize their surface energy. This assumption is based on the seminal work of Henrich which has shown faceting of the MgO(111) surface into {100} planes giving rise to three sided pyramids that have been observed by scanning electron microscopy. These surfaces had been prepared by mechanical polishing and phosphoric acid etching, followed by Ar+ sputtering and 1400 K annealing in ultra-high vacuum (UHV). More recent reflection electron microscopy studies of MgO(111) surfaces, annealed in the presence of oxygen at higher temperatures, have revealed relatively flat surfaces stabilized by an oxygen rich reconstruction. In this work we employ a combination of optical microscopy, transmission electron microscopy, and electron holography to further study the issue of surface faceting.

The Effect of Calcium and Magnesium on Rabbit Blood Platelet Aggregation in Vitro

1964 ◽  
Vol 12 (01) ◽  
pp. 179-200 ◽  
Author(s):  
Torstein Hovig
Keyword(s):  
Platelet Aggregation ◽  
Cation Exchange ◽  
Calcium Concentration ◽  
Blood Platelets ◽  
Blood Platelet ◽  
Rabbit Blood ◽  
Calcium And Magnesium ◽  
Induced Aggregation ◽  
Blood Platelet Aggregation

SummaryThe effect of calcium and magnesium on the aggregation of rabbit blood platelets in vitro was studied, with the following results:1. Platelet aggregation induced by ADP or collagen could be prevented by EGTA or EDTA. The aggregating effect was restored by recalcification. The effect was also restored by addition of magnesium in EDTA-PRP, but not in EGTA-PRP unless a surplus of calcium was present.2. Calcium remained in concentrations of the order of 0.15–0.25 mM after dialysis or cation exchange of plasma. Aggregation of washed platelets resuspended in such plasma could not be produced with ADP or collagen, unless the calcium concentration was increased or that magnesium was added.3. The adhesiveness of blood platelets to collagen was reduced in EGTA-PRP and EDTA-PRP. Release of ADP from platelets influenced by collagen could not be demonstrated either in EGTA-PRP (presence of magnesium) or in EDTA-PRP.4. It is concluded that calcium is a necessary factor both for the reaction leading to release of ADP and for the the aggregation produced by ADP.5. Thrombin induced aggregation of washed platelets suspended in tris-buffered saline in the presence of calcium. No effect of magnesium could be observed unless small quantities of calcium were present.

Hydrous oxides and their cation-exchange properties

1965 ◽  
Vol 15 (10) ◽  
pp. 445-448 ◽  
Author(s):  
C. Heitner-Wirguin ◽  
A. Albu-Yaron
Keyword(s):  
Cation Exchange ◽  
Hydrous Oxides ◽  
Exchange Properties
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