Above Room-Temperature Ferromagnetism in GaN Powders by Calcinations with CuO

2006 ◽  
Vol 941 ◽  
Author(s):  
Lori Noice ◽  
Bjoern Seipel ◽  
Rolf Erni ◽  
Amita Gupta ◽  
Chunfei Li ◽  
...  
Keyword(s):  
Copper Oxide ◽  
Room Temperature Ferromagnetism ◽  
Scanning Probe ◽  
Electronic Effects ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Oxide Phases ◽  
Probe Transmission ◽  
Electron Energy Loss

ABSTRACTGallium nitride powders were calcined with copper oxide in either air or N2 and analyzed by means of powder X-ray diffraction (XRD), high-resolution parallel illumination (HRTEM) and scanning probe transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDXS), and electron energy loss spectroscopy (EELS) in order to address the structural and electronic effects of Cu-incorporation into GaN. Gallium oxide and multiple copper oxide phases corresponding to the calcination environment were detected. Significant changes in the lattice parameters and electronic structure of the N2-processed GaN indicate incorporation of both copper and oxygen into the GaN lattice as well as changes in the chemical bonding due to the calcinations process. SQUID magnetometer measurements at 300 K demonstrated ferromagnetism in selected samples.

High-Pressure, High-Temperature Synthesis of Superhard Boron Suboxide

1995 ◽  
Vol 410 ◽  
Author(s):  
H. Hubert ◽  
L. A. J. Garvie ◽  
K. Leinenweber ◽  
P. R. Buseck ◽  
W. T. Petuskeyt ◽  
...  
Keyword(s):  
Pressure Range ◽  
X Ray Diffraction ◽  
Temperature Synthesis ◽  
X Ray ◽  
High Temperature Synthesis ◽  
Transmission Electron ◽  
High Pressure High Temperature ◽  
Boron Suboxide ◽  
Electron Energy Loss ◽  
Rhombohedral Boron

ABSTRACTA multianvil device was used to investigate the formation of BxO phases produced in the 2 to 10 GPa pressure range with temperatures between 1000 and 1800 °C.Amorphous and crystalline B and BP were oxidized using B2O3 and CrO3. Using powder X-ray diffraction and parallel electron energy-loss spectroscopy (PEELS), we were unable to detect graphitic or diamondstructured B2O, reported in previous studies. The refractory boride B6O, which has the α-rhombohedral boron structure, is the dominant suboxide in the P and T range of our investigation. PEELS with a transmission electron microscope was used to characterize the boron oxides.

Fabrication of boron carbonitride (BCN) nanotubes and giant fullerene cages

2010 ◽  
Vol 88 (12) ◽  
pp. 1256-1261 ◽  
Author(s):  
Guifang Sun ◽  
Faming Gao ◽  
Li Hou
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
The Novel ◽  
X Ray Diffraction ◽  
Boron Carbonitride ◽  
X Ray ◽  
Transmission Electron ◽  
New Form ◽  
First Time ◽  
Electron Energy Loss

Boron carbonitride (BCN) nanotubes have been successfully prepared using NH4Cl, KBH4, and ZnBr2 as the reactants at 480 °C for 12 h by a new benzene-thermal approach in a N2 atmosphere. As its by-product, a new form of carbon regular hexagonal nanocages are observed. The samples are characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), transmission electron diffraction (TED), electron energy loss spectroscopy (EELS), and high-resolution transmission electron microscopy (HRTEM). The prepared nanotubes have uniform outer diameters in the range of 150 to 500 nm and a length of up to several micrometerss. The novel carbon hexagonal nanocages have a typical size ranging from 100 nm to 1.5 µm, which could be the giant fullerene cages of [Formula: see text] (N = 17∼148). So, high fullerenes are observed for the first time. The influences of reaction temperature and ZnBr2 on products and the formation mechanism of BCN nanotubes are discussed.

scholarly journals Preparation and characterization of cobalt and copper oxide nanocrystals

2019 ◽  
Vol 37 (3) ◽  
pp. 347-352
Author(s):  
A. H. Moharram
Keyword(s):  
Microwave Irradiation ◽  
Copper Oxide ◽  
Chemical Precipitation ◽  
High Dispersion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Direct Band ◽  
Cuo Nanocrystals

AbstractCopper oxide and cobalt oxide (Co3O4, CuO) nanocrystals (NCs) have been successfully prepared using microwave irradiation. The obtained powders of the nanocrystals (NCs) were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric (TGA) analysis and Fourier-transform infrared spectroscopy. The obtained results confirm the presence of both nanooxides which have been produced during chemical precipitation using microwave irradiation. TEM micrographs have shown that the obtained nanocrystals are characterized by high dispersion and narrow size distribution. The results of X-ray diffraction confirmed those obtained from the transmission electron microscope. Optical absorption analysis indicated the direct band gap for both kinds of the nanocrystals.

Oxide Structures formed on Silver Single Crystals due to Hyperthermal Atomic Oxygen Exposure

2002 ◽  
Vol 751 ◽  
Author(s):  
Long Li ◽  
Judith C. Yang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Crystals ◽  
Atomic Oxygen ◽  
X Ray Diffraction ◽  
X Ray ◽  
Optical Scanning ◽  
Transmission Electron ◽  
Oxide Phases ◽  
Ag Substrate

ABSTRACTSilver (100) and (111) single crystals were exposed to a unique laser detonation atomic oxygen source, which produces a high flux of 5 eV atomic oxygen, for seven hours at 220°C. The resultant oxide and oxide-metal interfaces were characterized by optical, scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HREM). The oxide scale was more than 10-micron thick and very weakly attached to the Ag substrate. The silver oxides were complex and surprising, differ in their thickness and the oxide phases due to the orientation of the Ag single crystals. The cross-section TEM studies revealed complex microstructures with many defects, such as micro-twins, porosity and irregular shaped grains.

A study on the growth and structure of titania nanotubes

2004 ◽  
Vol 19 (2) ◽  
pp. 417-422 ◽  
Author(s):  
Wenzhong Wang ◽  
Oomman K. Varghese ◽  
Maggie Paulose ◽  
Craig A. Grimes ◽  
Qinglei Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chemical Process ◽  
Alkali Treatment ◽  
Titania Nanotubes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Spectroscopy Studies ◽  
Electron Energy Loss

Titania nanotubes synthesized by a soft chemical process are described, having diameters of 8 nm to 10 nm and lengths ranging from approximately 0.1 μm to 1 μm. X-ray diffraction studies show the structure of the as-prepared nanotubes is the same as that of the starting anatase TiO2nanoparticles. Energy-dispersive x-ray analysis and electron energy loss spectroscopy studies further indicate that the as-prepared nanotubes are composed of titania. Studies using transmission electron microscopy verified that the nanotubes are formed during alkali treatment, with subsequent acidic treatments having no effect on nanotube structure and shape.

Nanostructure of a Glass-Like Carbon Characterized by X-Ray Diffraction and Electron Energy Loss Spectroscopy

2010 ◽  
Vol 177 ◽  
pp. 58-61 ◽  
Author(s):  
Zhi Li Zhang ◽  
Rik Brydson ◽  
Aidan Westwood ◽  
B. Rand
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Treatment Temperature ◽  
X Ray Diffraction ◽  
Phenolic Resins ◽  
X Ray ◽  
Transmission Electron ◽  
Different Temperatures ◽  
Electron Energy Loss ◽  
Crystalline Graphite

In our present study, phenolic resins heated at different temperatures from 600 oC to 3000 oC were analysised in terms of phase structure and chemical structure using X-ray diffraction and high resolution transmission electron microscopy equipped with an electron energy loss spectrometer (EELS). It is shown that materials appear to be amorphous with many micro-pores surrounded by crystalline graphite layers; the formation of the pore is due to the gas evolution reaction. Using the intensities of peaks in EELS CK-ionization edge which arise from transition of an atomic 1s electron to the π* and σ* antibonding band-like states, the percentage of sp2-bonded carbon have been analyzed and the results reveal notable differences with heat treatment temperature.

Effect of Calcinations on Morphology of Electrospun Copper and Copper Oxide Nanofibers

2011 ◽  
Vol 52-54 ◽  
pp. 1884-1889 ◽  
Author(s):  
Dariush Jafar Khadem ◽  
Zahira Yaakob ◽  
Samaneh Shahgaldi ◽  
Wan Ramli Wan Daud ◽  
Edy Herianto Majlan
Keyword(s):  
Electron Microscopy ◽  
Copper Oxide ◽  
Sol Gel ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxide Nanostructures ◽  
Transmission Electron ◽  
Electrospinning Method ◽  
Potential Applications

Metal and Metal oxide nanofibers have different potential to play an essential role in a series of application, among them copper and copper oxide nanostructures is a promising semiconductor material with potential applications in many field. In this paper, electrospinning method via sol-gel was used to fabricate copper and copper oxide nanofibers. Synthesize of copper and copper oxide nanofibers and also effect of calcinations temperature on morphology investigated by thermal gravimetric analysis, scanning electron microscopy (SEM), Transmission electron microscopy, x-ray diffraction(XRD), Fourier transform infrared spectroscopy (FTIR) and Brunauer Emmett and Teller (BET).

scholarly journals A role for iron and oxygen chemistry in preserving soft tissues, cells and molecules from deep time

2014 ◽  
Vol 281 (1775) ◽  
pp. 20132741 ◽  
Author(s):  
Mary H. Schweitzer ◽  
Wenxia Zheng ◽  
Timothy P. Cleland ◽  
Mark B. Goodwin ◽  
Elizabeth Boatman ◽  
...  
Keyword(s):  
Soft Tissues ◽  
Iron Chelation ◽  
Chemical Degradation ◽  
X Ray Diffraction ◽  
Deep Time ◽  
Edge Structure ◽  
X Ray ◽  
Transmission Electron ◽  
Degradation Models ◽  
Electron Energy Loss

The persistence of original soft tissues in Mesozoic fossil bone is not explained by current chemical degradation models. We identified iron particles (goethite-αFeO(OH)) associated with soft tissues recovered from two Mesozoic dinosaurs, using transmission electron microscopy, electron energy loss spectroscopy, micro-X-ray diffraction and Fe micro-X-ray absorption near-edge structure. Iron chelators increased fossil tissue immunoreactivity to multiple antibodies dramatically, suggesting a role for iron in both preserving and masking proteins in fossil tissues. Haemoglobin (HB) increased tissue stability more than 200-fold, from approximately 3 days to more than two years at room temperature (25°C) in an ostrich blood vessel model developed to test post-mortem ‘tissue fixation’ by cross-linking or peroxidation. HB-induced solution hypoxia coupled with iron chelation enhances preservation as follows: HB + O 2 > HB − O 2 > −O 2 ≫ +O 2 . The well-known O 2 /haeme interactions in the chemistry of life, such as respiration and bioenergetics, are complemented by O 2 /haeme interactions in the preservation of fossil soft tissues.

scholarly journals Sodium-Vanadium Bronze Na9V14O35: An Electrode Material for Na-Ion Batteries

Molecules ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 86
Author(s):  
Maria A. Kirsanova ◽  
Alexey S. Akmaev ◽  
Mikhail V. Gorbunov ◽  
Daria Mikhailova ◽  
Artem M. Abakumov
Keyword(s):  
Negative Electrode ◽  
X Ray Diffraction ◽  
Conversion Reaction ◽  
X Ray ◽  
Electroactive Material ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Electrochemical Capacity ◽  
Silica Ampoule ◽  
Electron Energy Loss

Na9V14O35 (η-NaxV2O5) has been synthesized via solid-state reaction in an evacuated sealed silica ampoule and tested as electroactive material for Na-ion batteries. According to powder X-ray diffraction, electron diffraction and atomic resolution scanning transmission electron microscopy, Na9V14O35 adopts a monoclinic structure consisting of layers of corner- and edge-sharing VO5 tetragonal pyramids and VO4 tetrahedra with Na cations positioned between the layers, and can be considered as sodium vanadium(IV,V) oxovanadate Na9V104.1+O19(V5+O4)4. Behavior of Na9V14O35 as a positive and negative electrode in Na half-cells was investigated by galvanostatic cycling against metallic Na, synchrotron powder X-ray diffraction and electron energy loss spectroscopy. Being charged to 4.6 V vs. Na+/Na, almost 3 Na can be extracted per Na9V14O35 formula, resulting in electrochemical capacity of ~60 mAh g−1. Upon discharge below 1 V, Na9V14O35 uptakes sodium up to Na:V = 1:1 ratio that is accompanied by drastic elongation of the separation between the layers of the VO4 tetrahedra and VO5 tetragonal pyramids and volume increase of about 31%. Below 0.25 V, the ordered layered Na9V14O35 structure transforms into a rock-salt type disordered structure and ultimately into amorphous products of a conversion reaction at 0.1 V. The discharge capacity of 490 mAh g−1 delivered at first cycle due to the conversion reaction fades with the number of charge-discharge cycles.

Superhard B–C–N materials synthesized in nanostructured bulks

2002 ◽  
Vol 17 (12) ◽  
pp. 3139-3145 ◽  
Author(s):  
Y. Zhao ◽  
D. W. He ◽  
L. L. Daemen ◽  
T. D. Shen ◽  
R. B. Schwarz ◽  
...  
Keyword(s):  
High Pressure ◽  
Indentation Hardness ◽  
X Ray Diffraction ◽  
X Ray ◽  
Amorphous Phases ◽  
Transmission Electron ◽  
Pressure Synthesis ◽  
Nanocrystalline Composite ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

We report here the high-pressure synthesis of well-sintered millimeter-sized bulks of superhard BC2N and BC4N materials in the form of a nanocrystalline composite with diamond-like amorphous carbon grain boundaries. The nanostructured superhard B–C–N material bulks were synthesized under high P–T conditions from amorphous phases of the ball-milled molar mixtures. The synthetic B–C–N samples were characterized by synchrotron x-ray diffraction, high-resolution transmission electron microscope, electron energy-loss spectra, and indentation hardness measurements. These new high-pressure phases of B–C–N compound have extreme hardnesses, second only to diamond. Comparative studies of the high P–T synthetic products of BC2N, BC4N, and segregated phases of diamond + cBN composite confirm the existence of the single B–C–N ternary phases.

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