scholarly journals Crystal Structure, Microstructure and Electronic Properties of a Newly Discovered Ternary Phase in the Al-Cr-Sc System

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1535
Author(s):  
Monika Kušter ◽  
Anton Meden ◽  
Boštjan Markoli ◽  
Zoran Samardžija ◽  
Maja Vončina ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Density Functional ◽  
Ternary Phase ◽  
Total Density ◽  
X Ray Diffraction ◽  
Laves Phases ◽  
X Ray ◽  
Transmission Electron

This study focused on the crystal and electronic structures of a newly discovered phase in the Al-Cr-Sc system. The latter two species do not mix in a binary alloy, but can be alloyed with aluminium in the vicinity of the Al2−xCrxSc composition, where 0.3 < x < 0.5. After preparation of the pure constituents via arc melting, high-temperature annealing at 990 °C for 240 h was required to achieve full mixing of the elements. A detailed characterisation of the crystal structure, alloy microstructure and stability was obtained using single-crystal X-ray diffraction (SCXRD) and powder X-ray diffraction (PXRD), in addition to transmission electron microscopy (TEM), especially in high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) mode, scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDXS) and differential scanning calorimetry (DSC) measurements. The crystal structure was refined to a hexagonal unit cell of the MgZn2 type, space group no. 194, P63/mmc, which belongs to the Laves phases family. Special attention was paid to the occupancy of the crystallographic sites that were filled by both Cr and Al atoms. First-principles calculations based on the density functional theory (DFT) were performed to investigate the electronic structure of this ternary phase. The total density of states (DOS) exhibited a pronounced sp character, where a shallow pseudo-gap was visible 0.5 eV below the Fermi energy that brought a small but definite contribution to the thermodynamic stability of the compound.

Preparation and Luminescence Properties of ZnS: Cu/Fe Nanocrystalline

2014 ◽  
Vol 1033-1034 ◽  
pp. 1054-1057
Author(s):  
Xiang Zhang ◽  
Jin Liang Huang ◽  
Li Hua Li
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Thioglycolic Acid ◽  
Luminescent Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Zinc Blende ◽  
Transmission Electron ◽  
Fe Nanoparticles

ZnS: Cu/Fe nanocrystals were synthesized by hydrothermal method with thioglycolic acid as a stabilizer. The phases, grain size and luminescent properties of the nanocrystals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and fluorescence photometer respectively. The results showed that ZnS: Cu/Fe nanoparticles have a particle size about 7nm and possess a cubic zinc blende crystal structure. The luminous intensity of ZnS: Cu/Fe nanocrystals was strongly when they were reacted at 140°C for 12 hours.

FABRICATION AND CHARACTERISTICS OF ALN NANOWIRES

2001 ◽  
Vol 15 (30) ◽  
pp. 1455-1458 ◽  
Author(s):  
H. CHEN ◽  
X. K. LU ◽  
S. Q. ZHOU ◽  
X. H. HAO ◽  
Z. X. WANG
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Sublimation Method ◽  
Scanning Electron

Single phase AlN nanowires are fabricated by a sublimation method. They were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), typical selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The SEM and TEM images show that most of the nanowires have diameters of about 10–60 nm. The crystal structure of AlN nanowires revealed by XRD, SAED and HRTEM shows the AlN nanowires have a wurtzite structure.

Prepare of the New Structure PbTiO3 Nanowires and the Study of the Reversible Bending

2013 ◽  
Vol 331 ◽  
pp. 522-526
Author(s):  
Jiang Wang ◽  
Jian Li ◽  
You Wen Wang
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Stainless Steel ◽  
Hydrothermal Reaction ◽  
The Self ◽  
X Ray Diffraction ◽  
Electron Backscattered Diffraction ◽  
X Ray ◽  
Transmission Electron

When the self-made with Teflon lined with stainless steel reaction kettle is used to produce PbTiO3 nanowires with the adoption of hydrothermal reaction , PbTiO3 nanowires with new structure can be made when Pb/Ti equals 2.2. Observed through the Transmission Electron Microscopy (TEM), the bending feature of the PbTiO3 nanowires can be observed for several times when X-ray diffraction (XRD) and Electron Backscattered Diffraction (EBSD) are used to analyse and test the crystal structure of the nanowires. The result of the study shows that the degree of the bending of the PbTiO3 nanowires varies with the intensity of the electron beam from the Transmission Electron Microscopy, and its process can be reversible.

scholarly journals SPICA: stereographic projection for interactive crystallographic analysis

2016 ◽  
Vol 49 (5) ◽  
pp. 1818-1826 ◽  
Author(s):  
X.-Z. Li
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Stereographic Projection ◽  
Crystallographic Analysis ◽  
X Ray Diffraction ◽  
Orientation Relationships ◽  
X Ray ◽  
Research Fields ◽  
Transmission Electron

In numerous research fields, especially the applications of electron and X-ray diffraction, stereographic projection represents a powerful tool for researchers. SPICA is a new computer program for stereographic projection in interactive crystallographic analysis, which inherits features from the previous JECP/SP and includes more functions for extensive crystallographic analysis. SPICA provides fully interactive options for users to plot stereograms of crystal directions and crystal planes, traces, and Kikuchi maps for an arbitrary crystal structure; it can be used to explore the orientation relationships between two crystalline phases with a composite stereogram; it is also used to predict the tilt angles of transmission electron microscopy double-tilt and rotation holders in electron diffraction experiments. In addition, various modules are provided for essential crystallographic calculations.

The Influence of Catalyst Nature on the Morphology of Multi-Directionally Grown Carbon Nanofibers

2007 ◽  
Vol 26-28 ◽  
pp. 735-738
Author(s):  
Fei Li ◽  
Xiao Ping Zou ◽  
Jin Cheng
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Carbon Nanofibers ◽  
Catalytic Combustion ◽  
Close Relation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Combustion Technique

The multi-directional grown carbon nanofibers have been synthesized by catalytic combustion technique. Transmission electron microscopy and selected area electron X-ray diffraction were combined to characterize the carbon products and their catalyst, which promoted the formation of carbon nanofibers. The crystal structures of the catalyst were investigated. The present results indicate that the morphologies of the carbon nanofibers have a close relation with the crystal structure of the catalysts.

Structure of UMoO5 studied by single-crystal X-ray diffraction and high-resolution transmission electron microscopy

1996 ◽  
Vol 52 (6) ◽  
pp. 961-965 ◽  
Author(s):  
O. G. D'yachenko ◽  
V. V. Tabachenko ◽  
R. Tali ◽  
L. M. Kovba ◽  
B.-O. Marinder ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Slight Excess ◽  
Transmission Electron ◽  
Different Types

A combination of X-ray diffraction and high-resolution transmission electron microscopy (HRTEM) has been used to study the crystal structure of molybdenum uranium pentoxide, UMoO5, obtained by hydrothermal and ceramic methods. Crystal data: Mr = 414.0, orthorhombic, Pbaa (number 54), a = 12.746 (1), b = 7.3494 (7), c = 4.1252 (2) Å, V = 386.4 (1) Å3, Z = 4, Dx = 7.116 Mg m−3, R = 0.037 for 723 reflections. The structure of UMoO5 is related to that of UVO5. Both are built up by slabs of pentagonal UO7 bipyramids with slabs of MO6 octahedra in-between. They differ in symmetry due to different types of displacement of the M atoms from the ab plane. The HRTEM study revealed a few defect regions in the UMoO5 crystals prepared by ceramic methods. Energy-dispersive spectroscopy (EDS) analyses indicate a slight excess of uranium in such crystals. Hypothetical models of defect regions are given.

Structure of Oxides Grown on Zr-20Nb Alloy

1994 ◽  
Vol 357 ◽  
Author(s):  
O.T. Woo ◽  
D.J. Lockwood ◽  
Y.P. Lin ◽  
V.F. Urbanic
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Raman Spectra ◽  
High Symmetry ◽  
X Ray Diffraction ◽  
Short Term ◽  
X Ray ◽  
Transmission Electron

AbstractOxides grown on Zr-20Nb were characterized by Raman Spectroscopy (RS), X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). These oxides were steamformed at 400°C, water-formed at 360 °C and at 300 °C, and air-grown at 400°C. For the oxides grown after relatively short exposures at 360°C and at 400°C, Raman spectra revealed broad peaks at 260 and 660 cm− indicating a crystal structure with high symmetry. Comparison with reference Raman spectra of cubic (c), tetragonal (t), and monoclinic (m) ZrO2 suggested that the oxide was predominantly nearly-cubic (tetragonal with c/a ratio ≈ 1), with minor amounts of moxide. The tetragonality is found to be consistent with TEM analyses and XRD results which showed the presence of a doublet near 2θ ° 74°. The crystal structure in the short-term exposed oxides is interpreted in terms of a tetragonal distortion arising from the displacement of oxygen atoms within the cubic ZrO2 crystal structure. For oxides grown after longer periods of exposure at 300°C and at 400°C, RS and XRD indicate increased amounts of m-oxide.

scholarly journals THE FABRICATION OF Ag NANOPARTICLES LOADED TiO2 NANOTUBES BY PHOTOREDUCTION METHOD AND THEIR PHOTOCATALYTIC ACTIVITY

2018 ◽  
Vol 54 (1A) ◽  
pp. 199
Author(s):  
Pham Van Viet
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ag Nanoparticles ◽  
Tio2 Nanotubes ◽  
Annealing Temperature ◽  
X Ray Diffraction ◽  
Illumination Time ◽  
X Ray ◽  
Transmission Electron

In this paper, we survey the effect of the photoreduction (illumination) time and the annealing temperature on the formation of Ag nanoparticles supported on TiO2 nanotubes (Ag/TNTs). The morphology, crystal structure and compositions were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS), respectively. The results showed that Ag nanoparticles are supported on TNTs and the amount of Ag nanoparticles could be controlled. The morphology of TNTs can be changed by the photoreduction time and the annealing temperature.

Sign in / Sign up

Export Citation Format

Share Document