Complex Metallic Alloys – Microstructure Characterization

2013 ◽  
Vol 592-593 ◽  
pp. 483-488
Author(s):  
Jozef Janovec ◽  
Ivona Černičková ◽  
Pavol Priputen
Keyword(s):  
Electron Microscopy ◽  
Dark Field ◽  
Metallic Alloys ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Annular Dark Field ◽  
Points Of View ◽  
Complex Metallic Alloys

The recent findings related to binary and ternary structurally complex phases in selected complex metallic alloys coming under Al-Pd-Co, Al-Cu-Co, and Al-Mn-Fe systems are presented. The phases were characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, high-angle annular dark-field imaging, X-ray diffraction, and differential thermal analysis. There are highlighted some unusual features of phases D, U, T, and ε-family from both structural and compositional points of view.

scholarly journals Synthesis of nickel/gallium nanoalloys using a dual-source approach in 1-alkyl-3-methylimidazole ionic liquids

2019 ◽  
Vol 10 ◽  
pp. 1754-1767
Author(s):  
Ilka Simon ◽  
Julius Hornung ◽  
Juri Barthel ◽  
Jörg Thomas ◽  
Maik Finze ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Dark Field ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Annular Dark Field ◽  
Dual Source ◽  
Induced Decomposition

NiGa is a catalyst for the semihydrogenation of alkynes. Here we show the influence of different dispersion times before microwave-induced decomposition of the precursors on the phase purity, as well as the influence of the time of microwave-induced decomposition on the crystallinity of the NiGa nanoparticles. Microwave-induced co-decomposition of all-hydrocarbon precursors [Ni(COD)2] (COD = 1,5-cyclooctadiene) and GaCp* (Cp* = pentamethylcyclopentadienyl) in the ionic liquid [BMIm][NTf2] selectively yields small intermetallic Ni/Ga nanocrystals of 5 ± 1 nm as derived from transmission electron microscopy (TEM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and supported by energy-dispersive X-ray spectrometry (EDX), selected-area energy diffraction (SAED) and X-ray photoelectron spectroscopy (XPS). NiGa@[BMIm][NTf2] catalyze the semihydrogenation of 4-octyne to 4-octene with 100% selectivity towards (E)-4-octene over five runs, but with poor conversion values. IL-free, precipitated NiGa nanoparticles achieve conversion values of over 90% and selectivity of 100% towards alkene over three runs.

scholarly journals Annular Dark Field Imaging of Catalyst Nanoparticles in Single Shot Dynamic Transmission Electron Microscopy

2009 ◽  
Vol 15 (S2) ◽  
pp. 1082-1083
Author(s):  
D Masiel ◽  
B Reed ◽  
T LaGrange ◽  
ND Browning
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dark Field ◽  
Single Shot ◽  
Catalyst Nanoparticles ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Annular Dark Field ◽  
Field Imaging

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

Structure and Chemistry across Interfaces at Nanoscale of a Ge Quantum Well Embedded within Rare Earth Oxide Layers

2011 ◽  
Vol 17 (5) ◽  
pp. 759-765 ◽  
Author(s):  
Tanmay Das ◽  
Somnath Bhattacharyya
Keyword(s):  
Rare Earth ◽  
Solid Phase ◽  
Rare Earth Oxide ◽  
Dark Field ◽  
X Ray ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Annular Dark Field ◽  
Electron Energy Loss ◽  
Field Imaging

AbstractStructure and chemistry across the rare earth oxide-Ge interfaces of a Gd2O3-Ge-Gd2O3 heterostructure grown on p-Si (111) substrate using encapsulated solid phase epitaxy method have been studied at nanoscale using various transmission electron microscopy methods. The structure across both the interfaces was investigated using reconstructed phase and amplitude at exit plane. Chemistry across the interfaces was explored using elemental mapping, high-angle annular dark-field imaging, electron energy loss spectroscopy, and energy dispersive X-ray spectrometry. Results demonstrate the structural and chemical abruptness of both the interfaces, which is most essential to maintain the desired quantum barrier structure.

The quasiperiodic average structure of highly disordered decagonal Zn–Mg–Dy and its temperature dependence

2014 ◽  
Vol 70 (2) ◽  
pp. 315-330 ◽  
Author(s):  
Taylan Ors ◽  
Hiroyuki Takakura ◽  
Eiji Abe ◽  
Walter Steurer
Keyword(s):  
Single Crystal ◽  
Decomposition Temperature ◽  
Dark Field ◽  
Penrose Tiling ◽  
X Ray Diffraction ◽  
Decagonal Quasicrystal ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Annular Dark Field

A single-crystal X-ray diffraction structure analysis of decagonal Zn–Mg–Dy, a Frank–Kasper-type quasicrystal, was performed using the higher-dimensional approach. For this first Frank–Kasper (F–K) decagonal quasicrystal studied so far, significant differences to the decagonal Al–TM-based (TM: transition metal) phases were found. A new type of twofold occupation domain is located on certain edge centers of the five-dimensional unit cell. The structure can be described in terms of a two-cluster model based on a decagonal cluster (∼ 23 Å diameter) arranged on the vertices of a pentagon-Penrose tiling (PPT) and a star-like cluster covering the remaining space. This model is used for the five-dimensional refinements, which converged to anRvalue of 0.126. The arrangement of clusters is significantly disordered as indicated by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). In order to check the structure and stability at higher temperatures,in-situhigh-temperature (HT) single-crystal X-ray diffraction experiments were conducted at 598 and 648 K (i.e.slightly below the decomposition temperature). The structure does not change significantly, however, the best quasiperiodic order is found at 598 K. The implication of these results on the stabilization mechanism of quasicrystals is discussed.

scholarly journals (Al,Mg)3La: a new phase in the Mg–Al–La system

2018 ◽  
Vol 74 (4) ◽  
pp. 370-375 ◽  
Author(s):  
Charlotte Wong ◽  
Mark J. Styles ◽  
Suming Zhu ◽  
Dong Qiu ◽  
Stuart D. McDonald ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Powder Diffraction ◽  
Dark Field ◽  
Transmission Electron Microscopy Analysis ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Annular Dark Field ◽  
Electron Microscopy Analysis

During an investigation of the Mg-rich end of the Mg–Al–La system, a new ternary phase with the composition of (Al,Mg)3La was identified. The crystal structure of this phase was determined by conventional X-ray powder diffraction and transmission electron microscopy analysis and refined using high-resolution X-ray powder diffraction. The (Al,Mg)3La phase is found to have an orthorhombic structure with a space group of C2221 and lattice parameters of a = 4.3365 (1) Å, b = 18.8674 (4) Å and c = 4.4242 (1) Å, which is distinctly different from the binary Al3La phase (P63/mmc). The resolved structure of the (Al,Mg)3La phase is further verified by high-angle annular dark-field scanning transmission electron microscopy.

Effect of using polyimide capillaries during thermal experiments on the particle size distribution of supported Pt nanoparticles

2015 ◽  
Vol 48 (5) ◽  
pp. 1599-1603 ◽  
Author(s):  
Liliana Gámez-Mendoza ◽  
Oscar Resto ◽  
María Martínez-Iñesta
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Transmission Electron Microscopy ◽  
Low Cost ◽  
Pt Nanoparticles ◽  
Dark Field ◽  
High Angle ◽  
X Ray ◽  
Transmission Electron ◽  
Annular Dark Field

Kapton HN-type polyimide capillaries are commonly used as sample holders for transmission X-ray experiments at temperatures below 673 K because of their thermal stability, high X-ray transmittance and low cost. Using high-angle annular dark field scanning high-resolution transmission electron microscopy and thermogravimetric analysis, this work shows that using polyimide capillaries leads to the overgrowth of supported Pt nanoparticles during reduction at temperatures below the glass transition temperature (Tg= 658 K) owing to an outgassing of water from the polyimide. Quartz capillaries were also studied and this overgrowth was not observed.

Green Zn3Al2Ge2O10: Mn2+ Phosphors: Solid-Phase Synthesis, Structure, and Luminescent Properties

2019 ◽  
Vol 74 (12) ◽  
pp. 1109-1113
Author(s):  
Wenlin Feng ◽  
Xiaozhan Yang ◽  
Jin Peng ◽  
Yike Zhang ◽  
Weiqiang Chen
Keyword(s):  
Solid Phase ◽  
Green Emission ◽  
Luminescent Properties ◽  
Energy Dispersive Spectrum ◽  
Dark Field ◽  
Spectroscopic Techniques ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Annular Dark Field

AbstractNovel green phosphors Zn3Al2Ge2O10: Mn2+ were successfully synthesised at high temperature under weak reducing atmosphere. X-ray diffraction results indicate that the samples have like-spinel structure. The morphology, chemical states, and the composition of the dopants in the host were analysed with high-resolution transmission electron microscopy, energy dispersive spectrum, high-angle annular dark-field, and X-ray photoelectron spectroscopic techniques. The photoluminescence spectra show that the emission peak is at 537 nm (under excitation at λex = 334 nm), which is the strong green emission resulting from the 4T1 (4G)-6A1 (6S) transition of Mn2+ ion. The full width at half maximum broadband of the strongest broad emission is about 50 nm. The Zn3Al2Ge2O10 doped with 4 mol% Mn2+ appears to have the highest emission intensity after thermal treatment at 1250 °C for 5 h. The CIE coordinates are x = 0.279, y = 0.625, corresponding to green region, and the decay time is 4.88 μs. The results indicate that the phosphors may be used as a trichromatic fluorescent material.

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