Partial cation-order and early-stage, phase separation in phase W, Li x Co 1− x O: 0.075≤ x ≤0.24−0.31

2009 ◽  
Vol 465 (2106) ◽  
pp. 1829-1841 ◽  
Author(s):  
Y. Wu ◽  
D. Pasero ◽  
E.E. McCabe ◽  
Y. Matsushima ◽  
A.R. West
Keyword(s):  
Phase Separation ◽  
Early Stage ◽  
Domain Size ◽  
Solid Solution Phase ◽  
X Ray ◽  
Cation Order ◽  
Transmission Electron ◽  
X Ray Absorption ◽  
Li Content ◽  
Disordered Regions

We report the characterization using X-ray and neutron powder diffraction, transmission electron microscopy and extended X-ray absorption fine structure of a new, partially ordered rock-salt-like solid solution phase Li x Co 1− x O: 0.075≤ x ≤0.24−0.31. The cation stacking sequence along [111] consists of alternating planes of Co and Co/Li. Nano-sized domains of this cation-ordered phase appear alongside disordered regions; domain size increases from 2 to 8 nm with increasing Li content. Compositions of ordered and disordered regions are Li- and Co-rich, respectively, and, therefore, the phase exhibits frozen-in, incipient phase separation. This microstructure could be considered as a precursor to precipitation of fully ordered, rhombohedral LiCoO 2 .

Ordering With Phase Separation in an Fe-Al-Si Alloy

1983 ◽  
Vol 21 ◽  
Author(s):  
S. Matsumura ◽  
A. Sonobe ◽  
K. Oki ◽  
T. Eguchi
Keyword(s):  
Phase Separation ◽  
Early Stage ◽  
X Ray Diffraction ◽  
Modulated Structure ◽  
X Ray ◽  
Prolonged Annealing ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Degree Of Order ◽  
Phase Proceeds

ABSTRACTTwo kinds of process of ordering with phase separation, B2 or DO3 → (A2 + DO3), on annealing at a temperature of 873 K in an alloy of Fe-6 at%Al-9 at%Si were investigated by means of transmission electron microscopy and X-ray diffraction. The decomposition of DO3 phase proceeds by the development of periodic fluctuations along <100> directions in both B2 and DO3 types of degree of order. Newly born DO3 domains take the form of rectangular prism and align along <100> directions. In the transition from B2, on the contrary, there is a marked difference between the morphologies of the fluctuations in the two types of degree of order at the early stage of annealing. The degree of B2 type order fluctuates along <100> directions, while the fluctuation in the degree of DO3 type order does not form the <100> modulated structure sat the early stage of annealing. The morphology after a prolonged annealing is similar to that in the case of DO3 → (A2 + DO3).

X-ray microanalysis of thin specimens in the transmission electron microscope at voltages up to 1000 Kv.

1978 ◽  
Vol 36 (1) ◽  
pp. 540-541
Author(s):  
G. Cliff ◽  
M.J. Nasir ◽  
G.W. Lorimer ◽  
N. Ridley
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Weight Fraction ◽  
Present Series ◽  
Constant Independent ◽  
X Ray ◽  
Transmission Electron ◽  
Series Of Experiments ◽  
Image Position ◽  
X Ray Absorption

In a specimen which is transmission thin to 100 kV electrons - a sample in which X-ray absorption is so insignificant that it can be neglected and where fluorescence effects can generally be ignored (1,2) - a ratio of characteristic X-ray intensities, I1/I2 can be converted into a weight fraction ratio, C1/C2, using the equationwhere k12 is, at a given voltage, a constant independent of composition or thickness, k12 values can be determined experimentally from thin standards (3) or calculated (4,6). Both experimental and calculated k12 values have been obtained for K(11<Z>19),kα(Z>19) and some Lα radiation (3,6) at 100 kV. The object of the present series of experiments was to experimentally determine k12 values at voltages between 200 and 1000 kV and to compare these with calculated values.The experiments were carried out on an AEI-EM7 HVEM fitted with an energy dispersive X-ray detector.

scholarly journals Structural Evolution in Wet Mechanically Alloyed Co-Fe-(Ta,W)-B Alloys

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 800
Author(s):  
Vladimír Girman ◽  
Maksym Lisnichuk ◽  
Daria Yudina ◽  
Miloš Matvija ◽  
Pavol Sovák ◽  
...  
Keyword(s):  
Structural Changes ◽  
Magnetic Measurements ◽  
Structural Evolution ◽  
High Energy ◽  
Control Agent ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray ◽  
Transmission Electron ◽  
X Ray Absorption

In the present study, the effect of wet mechanical alloying (MA) on the glass-forming ability (GFA) of Co43Fe20X5.5B31.5 (X = Ta, W) alloys was studied. The structural evolution during MA was investigated using high-energy X-ray diffraction, X-ray absorption spectroscopy, high-resolution transmission electron microscopy and magnetic measurements. Pair distribution function and extended X-ray absorption fine structure spectroscopy were used to characterize local atomic structure at various stages of MA. Besides structural changes, the magnetic properties of both compositions were investigated employing a vibrating sample magnetometer and thermomagnetic measurements. It was shown that using hexane as a process control agent during wet MA resulted in the formation of fully amorphous Co-Fe-Ta-B powder material at a shorter milling time (100 h) as compared to dry MA. It has also been shown that substituting Ta with W effectively suppresses GFA. After 100 h of MA of Co-Fe-W-B mixture, a nanocomposite material consisting of amorphous and nanocrystalline bcc-W phase was synthesized.

scholarly journals In Situ Investigation of the Early-Stage Growth of Nanoporous Alumina

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Thérèse Gorisse ◽  
Ludovic Dupré ◽  
Marc Zelsmann ◽  
Alina Vlad ◽  
Alessandro Coati ◽  
...  
Keyword(s):  
Early Stage ◽  
Grazing Incidence ◽  
Alumina Layer ◽  
Nanoporous Alumina ◽  
X Ray ◽  
X Ray Scattering ◽  
In Situ Investigation ◽  
Low X ◽  
X Ray Absorption

We report the successful use of in situ grazing incidence small-angle X-ray scattering to follow the anodization of aluminum. A dedicated electrochemical cell was designed and developed for this purpose with low X-ray absorption, with the possibility to access all azimuthal angles (360°) and to remotely control the temperature of the electrolyte. Three well-known fabrication techniques of nanoporous alumina, i.e., single, double, and pretextured, were investigated. The differences in the evolution of the scattering images are described and explained. From these measurements, we could determine at which moment the pores start growing even for very short anodization times. Furthermore, we could follow the thickness of the alumina layer as a function of the anodization time by monitoring the period of the Kiessig fringes. This work is aimed at helping to understand the different steps taking place during the anodization of aluminum at the very early stages of nanoporous alumina formation.

Size dependent behavior of Fe3O4crystals during electrochemical (de)lithiation: an in situ X-ray diffraction, ex situ X-ray absorption spectroscopy, transmission electron microscopy and theoretical investigation

2017 ◽  
Vol 19 (31) ◽  
pp. 20867-20880 ◽  
Author(s):  
David C. Bock ◽  
Christopher J. Pelliccione ◽  
Wei Zhang ◽  
Janis Timoshenko ◽  
K. W. Knehr ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
X Ray ◽  
Size Dependent ◽  
Transmission Electron ◽  
Dependent Behavior ◽  
X Ray Absorption

Crystal and atomic structural changes of Fe3O4upon electrochemical (de)lithiation were determined.

Structural aspects of the hisingerite-neotocite series

Clay Minerals ◽  
1983 ◽  
Vol 18 (1) ◽  
pp. 21-31 ◽  
Author(s):  
R. A. Eggleton ◽  
J. H. Pennington ◽  
R. S. Freeman ◽  
I. M. Threadgold
Keyword(s):  
Function Analysis ◽  
Pore Space ◽  
Hollow Spheres ◽  
X Ray ◽  
Broken Hill ◽  
Transmission Electron ◽  
X Ray Absorption ◽  
Interconnected Pore ◽  
Intermediate Member ◽  
Structural Aspects

AbstractTransmission electron microscopy, X-ray radial distribution function analysis, chemical analysis, X-ray absorption edge spectroscopy, and Mössbauer spectroscopy combine to confirm an amorphous or gel structure for minerals of the hisingerite-neotocite series: (Fe,Mn)0.8SiO3.1.2H2O. A framework of (Fe,Mn)O6 octahedra and [SiO4] tetrahedra form hollow spheres, 50–100 Å in diameter, cross-bonded into a physically isotropic solid with as much as 10% interconnected pore space. The outer 10–20 Å of the spheres has a rudimentary structure, possibly marking the onset of segregation into Si-rich and (Fe,Mn)-rich layers. The Broken Hill mineral ‘sturtite’ is an intermediate member of the hisingerite-neotocite series.

scholarly journals Volcano-Type Correlation between Particle Size and Catalytic Activity on Hydrodechlorination catalyzed by AuPd Nanoalloy

2020 ◽  
Author(s):  
Yuta Uetake ◽  
Sachi Mouri ◽  
Setsiri Haesuwannakij ◽  
Kazu Okumura ◽  
Hidehiro Sakurai
Keyword(s):  
Catalytic Activity ◽  
Metal Ion ◽  
Mixing Time ◽  
Metal Nanoparticle ◽  
Edge Structure ◽  
X Ray ◽  
Rate Determining Step ◽  
Transmission Electron ◽  
Random Alloy ◽  
X Ray Absorption

<div>Although changing the size of metal nanoparticle (NP) is a reasonable way to tune and/or enhance their catalytic activity, size-selective preparation of NP possessing random-alloy morphology has been challenging because of the differences in the ionization potential of each metal ion. This study demonstrates a time-controlled aggregation–stabilization method for a size-selective preparation of random alloy NPs composed of Au and Pd, which are stabilized by poly(<i>N</i>-vinyl-2-pyrrolidone) (PVP). By adjusting the mixing time in the presence of a small amount of PVP, the aggregation was induced to produce AuPd:PVP with sizes ranging between 1.2 and 8.2 nm at approximately 1 nm intervals. Transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and extended x-ray absorption fine structure (EXAFS) analyses clearly indicated the formation of various sizes of AuPd nanoalloys with almost the same morphology, and size-dependent catalytic activity was observed when hydrodechlorination of 4-choroanisole was performed using 2-propanol as a reducing agent. AuPd:PVP with a size of 3.1 nm exhibited the highest catalytic activity. A comparison of the absorption edges on x-ray absorption near edge structure (XANES) spectra suggested that the electronic state of the Au and Pd species correlated with their catalytic activity, presumably affecting the rate-determining step.</div><div> </div>

scholarly journals Observation and Characterization of Fragile Organometallic Molecules Encapsulated in Single-Wall Carbon Nanotubes

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
Daisuke Ogawa ◽  
Ryo Kitaura ◽  
Takeshi Saito ◽  
Shinobu Aoyagi ◽  
Eiji Nishibori ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
High Yield ◽  
Single Wall Carbon Nanotubes ◽  
X Ray Diffraction ◽  
Single Wall Carbon ◽  
X Ray ◽  
Transmission Electron ◽  
Organometallic Molecules ◽  
X Ray Absorption

Thermally fragile tris(η5-cyclopentadienyl)erbium (ErCp3) molecules are encapsulated in single-wall carbon nanotubes (SWCNTs) with high yield. We realized the encapsulation of ErCp3with high filling ratio by using high quality SWCNTs at an optimized temperature under higher vacuum. Structure determination based on high-resolution transmission electron microscope observations together with the image simulations reveals the presence of almost free rotation of each ErCp3molecule in SWCNTs. The encapsulation is also confirmed by X-ray diffraction. Trivalent character of Er ions (i.e., Er3+) is confirmed by X-ray absorption spectrum.

Sign in / Sign up

Export Citation Format

Share Document