scholarly journals Facile phase transfer of gold nanorods and nanospheres stabilized with block copolymers

2018 ◽  
Vol 9 ◽  
pp. 616-627 ◽  
Author(s):  
Yaroslav I Derikov ◽  
Georgiy A Shandryuk ◽  
Raisa V Talroze ◽  
Alexander A Ezhov ◽  
Yaroslav V Kudryavtsev
Keyword(s):  
Ligand Exchange ◽  
Au Nanoparticles ◽  
Phase Transfer ◽  
Hybrid Composites ◽  
Transmission Electron Microscopy Data ◽  
Optical Absorbance ◽  
Nanoparticle Surface ◽  
Transmission Electron ◽  
Fast Route ◽  
Microscopy Data

A fast route to transfer Au nanoparticles from aqueous to organic media is proposed based on the use of a high molecular mass diblock copolymer of styrene and 2-vinylpyridine for ligand exchange at the nanoparticle surface. The method enables the preparation of stable sols of Au nanorods with sizes of up to tens of nanometers or Au nanospheres in various organic solvents. By comparing the optical absorbance spectra of Au hydro- and organosols with the data of numerical simulations of the surface plasmon resonance, we find that nanoparticles do not aggregate and confirm the transmission electron microscopy data regarding their shape and size. The proposed approach can be effective in preparing hybrid composites without the use of strong thiol and amine surfactants.

Initial Dynamic Susceptibility of Maghemite Nanoparticles Dispersed in Surface-Treated Polymeric Template

2021 ◽  
Vol 21 (11) ◽  
pp. 5694-5697
Author(s):  
A. F. R. Rodriguez ◽  
R. F. Lacerda ◽  
L. E. Maggi ◽  
Hory Mohammadpour ◽  
Mohammad Niyaifar ◽  
...  
Keyword(s):  
Ex Situ ◽  
Transmission Electron Microscopy Data ◽  
Dynamic Susceptibility ◽  
Maghemite Nanoparticles ◽  
X Ray Diffraction ◽  
Chemical Treatments ◽  
Dynamical Susceptibility ◽  
Transmission Electron ◽  
Microscopy Data ◽  
Polymeric Template

Magnetic nanocomposites based on maghemite nanoparticles supported (ex situ route) on styrene- divinilbenzene (Sty-DVB) copolymer templates were produced and characterized for their structure and morphology. The as-produced nanocomposites were further chemically-treated with different oxidant agents and surface-coated with stearic acid. X-ray diffraction and transmission electron microscopy data show that the incorporated nanoparticles are preserved despite the aggressive chemical treatments employed. From the dynamical susceptibility measurements performed on the nanocomposites, the values of the saturation magnetization (76 emu/g) and the effective magnetic anisotropy (1.7 × 104 J/m3) were obtained, in excellent agreement with the values reported in the literature for maghemite. This finding strongly supports the preservation of the magnetic properties of the supported nanosized maghemite throughout the entire samples’ processing.

Effect of the Pulse Laser Radiation on the Stabilization of the ZrO2 and HFO2 High-Temperature Phases

2015 ◽  
Vol 245 ◽  
pp. 200-203 ◽  
Author(s):  
Maxim Alexandrovich Pugachevskii ◽  
Viktor Igorevich Panfilov
Keyword(s):  
High Temperature ◽  
Transmission Electron Microscopy Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Good Thermal Stability ◽  
Quantitative Content ◽  
Electron Microscopy Data ◽  
Cubic Phases ◽  
Transmission Electron ◽  
Microscopy Data

The conditions of formation of the ZrO2 and HfO2 high-temperature (tetragonal and cubic) phases in the ablated nanoparticles were investigated. X-ray diffraction and transmission electron microscopy data demonstrate that laser intensities above 109 W/m2 ensure the formation of the ZrO2 high-temperature phases, while intensities above 5·109 W/m2 do the formation of the HfO2 high-temperature phases. Quantitative content of the high-temperature phases in layers of the ablated nanoparticles increases with raising the intensity. The obtained nanoparticles exhibit good thermal stability.

A Critical Investigation on the Existence of Selective Microwave Absorption in the Synthesis of CdSe Quantum Dots

2014 ◽  
Vol 67 (9) ◽  
pp. 1180 ◽  
Author(s):  
Mojtaba Mirhosseini Moghaddam ◽  
C. Oliver Kappe
Keyword(s):  
Quantum Dots ◽  
Microwave Absorption ◽  
Transmission Electron Microscopy Data ◽  
Microwave Assisted Synthesis ◽  
Cdse Quantum Dots ◽  
X Ray Diffraction ◽  
Heating And Cooling ◽  
Transmission Electron ◽  
Microscopy Data ◽  
Heating Mode

The existence of selective microwave absorption phenomena in the synthesis of CdSe quantum dots has been investigated. These types of microwave effects involving selective microwave absorption by specific reagents have recently been proposed in the microwave-assisted synthesis of various nanoparticles. In the present study, the microwave synthesis of CdSe quantum dots was investigated according to a protocol published by Washington and Strouse to clarify the presence of selective microwave heating. Importantly, control experiments involving conventional conductive heating were executed under otherwise (except for the heating mode) identical conditions, ensuring the same heating and cooling profiles, stirring rates, and reactor geometries. Comparison of powder X-ray diffraction, UV-vis, photoluminescence, and transmission electron microscopy data of the obtained CdSe quantum dots reveals that identical types of nanoparticles are obtained independently of the heating mode. Therefore, no evidence for a selective microwave absorption phenomenon could be obtained.

Optimizing Contact Resistance at a Resistor/Conductor Interface via Thin Film Microanalysis and Process Design of Experiments

1999 ◽  
Author(s):  
J.H. Linn ◽  
T.K. Thompson ◽  
M.G. Shlepr
Keyword(s):  
Thin Film ◽  
Contact Resistance ◽  
Amorphous Layer ◽  
Transmission Electron Microscopy Data ◽  
Silicon Carbon ◽  
Transmission Electron ◽  
Two Factors ◽  
Designed Experiment ◽  
Thin Film Resistors ◽  
Microscopy Data

Abstract Electrical data from chromium-silicon-carbon (CrSiC) thin film resistors (tfr) consistently showed highly variable contact resistance (Rc) to the aluminum (Al) interconnect. Transmission electron microscopy data from CrSiC/Al interfaces exhibiting high Rc showed a conformal, amorphous layer sandwiched between the tfr and Al. Auger data from the tfr/Al interface showed this ‘crud’ layer to contain increased C, S, and SiOx. Auger data from CrSiC films on test wafers exposed to the process steps before Al deposition showed additional growth of the ‘crud’ layer after each photoresist (PR) operation. In addition, Rc variability was reduced on product wafers from split lots when 2x the normal PR strip time was used compared to the normal strip time. A Designed Experiment (DOE) to examine improving the removal of this ‘crud’ layer was run on product lots utilizing two factors: the standard strip and a two-step strip. Electrical results for both Rc and die yield were significantly improved using the two-step process. The variability of the Rc was also reduced.

scholarly journals Nanoscale evidence for temperature-induced transient rheology and postseismic fault healing

Geology ◽  
2019 ◽  
Vol 47 (12) ◽  
pp. 1203-1207 ◽  
Author(s):  
A.K. Ault ◽  
J.L. Jensen ◽  
R.G. McDermott ◽  
F.-A. Shen ◽  
B.R. Van Devener
Keyword(s):  
Thermal Evolution ◽  
Heating Temperature ◽  
Transmission Electron Microscopy Data ◽  
Silica Films ◽  
Crystallographic Preferred Orientation ◽  
Transmission Electron ◽  
Transient Rheology ◽  
Microscopy Data ◽  
Evolution Control ◽  
Fault Healing

Abstract Friction-generated heat and the subsequent thermal evolution control fault material properties and thus strength during the earthquake cycle. We document evidence for transient, nanoscale fault rheology on a high-gloss, light-reflective hematite fault mirror (FM). The FM cuts specularite with minor quartz from the Pleistocene El Laco Fe-ore deposit, northern Chile. Scanning and transmission electron microscopy data reveal that the FM volume comprises a <50-μm-thick zone of polygonal hematite nanocrystals with spherical silica inclusions, rhombohedral twins, no shape or crystallographic preferred orientation, decreasing grain size away from the FM surface, and FM surface magnetite nanoparticles and Fe2+ suboxides. Sub–5-nm-thick silica films encase hematite grains and connect to amorphous interstitial silica. Observations imply that coseismic shear heating (temperature >1000 °C) generated transiently amorphous, intermixed but immiscible, and rheologically weak Fe-oxide and silica. Hematite regrowth in a fault-perpendicular thermal gradient, sintering, twinning, and a topographic network of nanometer-scale ridges from crystals interlocking across the FM surface collectively restrengthened fault material. Results reveal how temperature-induced weakening preconditions fault healing. Nanoscale transformations may promote subsequent strain delocalization and development of off-fault damage.

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