scholarly journals Состав, электронное и атомное строение наночастиц палладия при различных концентрациях металла в матрице полиэтилена

2020 ◽  
Vol 46 (7) ◽  
pp. 20
Author(s):  
С.С. Подсухина ◽  
А.В. Козинкин ◽  
В.Г. Власенко ◽  
Г.Ю. Юрков ◽  
О.В. Попков
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Palladium Nanoparticles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coordination Numbers ◽  
Transmission Electron ◽  
High Pressure Polyethylene ◽  
Average Size ◽  
X Ray Absorption

The composition, electronic and atomic structure of palladium nanoparticles stabilized in high pressure polyethylene (with palladium concentrations of 10 and 20 mass%) were studied by transmission electron microscopy, X-ray diffraction, and X-ray absorption spectroscopy. It was found that nanoparticles consist of metal (Pd) and oxide (Pd2O3) components, and their average size and coordination numbers for first Pd coordination sphere decrease(from 7 to 6 nm and from 7 to 5.7, respectively) with a decrease in metal concentration.

Structural, morphological, and magnetic study of nanocrystalline cobalt-copper powders synthesized by the polyol process

1995 ◽  
Vol 10 (6) ◽  
pp. 1546-1554 ◽  
Author(s):  
G.M. Chow ◽  
L.K. Kurihara ◽  
K.M. Kemner ◽  
P.E. Schoen ◽  
W.T. Elam ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Copper Powders ◽  
Face Centered ◽  
Increasing Temperature ◽  
X Ray Absorption

Nanocrystalline CoxCu100−x (4 ⋚ x ⋚ 49 at. %) powders were prepared by the reduction of metal acetates in a polyol. The structure of powders was characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), extended x-ray absorption fine structure (EXAFS) spectroscopy, solid-state nuclear magnetic resonance (NMR) spectroscopy, and vibrating sample magnetometry (VSM). As-synthesized powders were composites consisting of nanoscale crystallites of face-centered cubic (fcc) Cu and metastable face-centered cubic (fcc) Co. Complementary results of XRD, HRTEM, EXAFS, NMR, and VSM confirmed that there was no metastable alloying between Co and Cu. The NMR data also revealed that there was some hexagonal-closed-packed (hcp) Co in the samples. The powders were agglomerated, and consisted of aggregates of nanoscale crystallites of Co and Cu. Upon annealing, the powders with low Co contents showed an increase in both saturation magnetization and coercivity with increasing temperature. The results suggested that during preparation the nucleation of Cu occurred first, and the Cu crystallites served as nuclei for the formation of Co.

Receiving Copper Nanoparticles: Experiment and Modelling

2019 ◽  
Vol 288 ◽  
pp. 140-147 ◽  
Author(s):  
Andrey V. Nomoev ◽  
Erzhena C. Khartaeva ◽  
Natalia V. Yumozhapova ◽  
Tumen G. Darmaev ◽  
S.P. Bardakhanov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Copper Nanoparticles ◽  
Pure Copper ◽  
Current Strength ◽  
X Ray Diffraction ◽  
X Ray ◽  
Embedded Atom ◽  
Transmission Electron ◽  
Average Size

The copper nanoparticles were obtained by evaporating the metal by the relativistic electron beam. The average size of synthesized particles was about 120 nm. They were characterized by X-ray diffraction, transmission electron microscopy. The results of the X-ray diffraction showed high content of the pure copper for closed setup with an inert gas. Transmission electron microscopy cleared some particles to have an icosahedral structure. These nanoparticles were obtained when the target was exposed by the beam with the highest current strength used in the experiment and the highest cooling of the copper vapor. The process of copper nanoparticle formation by the molecular dynamic method using EAM – potentials (potentials in the Embedded Atom Method form) was studied.

scholarly journals Effect of metal precursors on polyol synthesis of palladium nanoparticles towards C-N bond formation

2020 ◽  
Vol 9 (4) ◽  
pp. 88-92
Author(s):  
Trung Dang Bao ◽  
Phuong Phan Hong ◽  
Mai Tran Thuy Tuyet
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Palladium Nanoparticles ◽  
Bond Formation ◽  
Polyol Synthesis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Catalytic Activities ◽  
Transmission Electron ◽  
Metal Precursors

In the present work, palladium nanoparticles were synthesized in glycerol following the bottom-up methodology, using Pd(II) and Pd(0) precursors. The as-prepared materials were characterized by transmission electron microscopy (TEM) and powder X-ray diffraction (XRD), evidencing the formation of zero-valent palladium spheres in the nanosize ranges. The effects of metal precursors on the size of nanoparticles and their dispersion in medium reaction were illuminated, accompanying with the different catalytic activities towards C-N bond formation between acrylonitrile and morpholine. In particular, the recycling of catalytic phase was also desired thanks to immobilization of PdNPs in glycerol.

scholarly journals Comparative study on catalytic reactivity of colloidal Ni(0)NPs and Pd(0)NPs towards semi-hydrogenation of alkynes

2021 ◽  
Vol 10 (2) ◽  
pp. 84-89
Author(s):  
Phuong Phan Hong ◽  
Phuong Nguyen Thi Hong ◽  
Hung Lam Hoa ◽  
Trung Dang Bao
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Palladium Nanoparticles ◽  
Hydrogen Pressure ◽  
Nickel Nanoparticles ◽  
Terminal Alkynes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Catalytic Reactivity

In this study, nickel nanoparticles (Ni(0)NPs) and palladium nanoparticles (Pd(0)NPs) were prepared in neat glycerol under hydrogen pressure by the bottom-up approach. The formation of zero-valent metal nanospheres was evidenced by transmission electron microscopy (TEM) and powder X-ray diffraction (XRD) analyses. Regarding their catalytic behaviors, Ni(0)NPs permitted to obtain the corresponding (Z)-alkenes in the semi-hydrogenation of both internal and terminal alkynes. In contrast, over-hydrogenations of such alkynes towards the alkanes were observed over Pd(0)NPs after only 2 hours of reaction. Interestingly, the catalytic phase of Ni(0)NPs in glycerol could be recycled up to 5 times, preserving their catalytic activity and selectivity.      

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

1982 ◽  
Vol 40 ◽  
pp. 722-723 ◽  
Author(s):  
R. Gronsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

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