scholarly journals Determination Morse Potential Parameters by the Theoretical Method in EXAFS

2021 ◽  
Author(s):  
Nguyen Ba Duc ◽  
Trinh Phi Hiep ◽  
Nguyen Thu
Keyword(s):  
Morse Potential ◽  
Theoretical Method ◽  
Relative Displacement ◽  
Face Centered Cubic ◽  
Effective Parameters ◽  
Face Centered ◽  
Silicon And Germanium ◽  
Experimental Values ◽  
X Ray Absorption ◽  
Potential Parameters

Abstract A new method for estimating Morse potential's effective parameters has developed using the sublimation energy, the compressibility, and the lattice constant in expanded X-ray absorption fine structure spectra. Application the received parameters of Morse potential to calculate the mean square relative displacement, elastic constant, anharmonic effective potential, correlated function, and local force constant for diamond-type structure crystals such as silicon and germanium crystals, and face-centered cubic crystals as copper, silver. Numerical results agree well with the experimental values and other theories.

scholarly journals High-pressure study of thermodynamic parameters of diamond-type structured crystals using interatomic Morse potentials

2021 ◽  
Vol 68 (1) ◽  
Author(s):  
Duc Ba Nguyen ◽  
Hiep Phi Trinh
Keyword(s):  
High Pressure ◽  
Thermodynamic Parameters ◽  
Relative Displacement ◽  
The Mean ◽  
Experimental Values ◽  
X Ray Absorption ◽  
Potential Parameters ◽  
Diamond Type ◽  
High Pressure Study ◽  
Morse Potentials

AbstractIn this work, we have determined the mean square relative displacement, elastic constant, anharmonic effective potential, correlated function, local force constant, and other thermodynamic parameters of diamond-type structured crystals under high-pressure up to 14 GPa. The parameters are calculated through theoretical interatomic Morse potential parameters, by using the sublimation energy, the compressibility, and the lattice constant in the expanded X-ray absorption fine structure spectrum. Numerical results agree well with the experimental values and other theories.

Stress-Strain Relations and Vibrations of a Granular Medium

1957 ◽  
Vol 24 (4) ◽  
pp. 585-593
Author(s):  
J. Duffy ◽  
R. D. Mindlin
Keyword(s):  
Energy Dissipation ◽  
Contact Forces ◽  
Face Centered Cubic ◽  
Stress Strain ◽  
Differential Stress ◽  
Elastic Bodies ◽  
Strain Relation ◽  
Stress Strain Relation ◽  
Face Centered ◽  
Experimental Values

Abstract A differential stress-strain relation is derived for a medium composed of a face-centered cubic array of elastic spheres in contact. The stress-strain relation is based on the theory of elastic bodies in contact, and includes the effects of both normal and tangential components of contact forces. A description is given of an experiment performed as a test of the contact theories and the differential stress-strain relation derived from them. The experiment consists of a determination of wave velocities and the accompanying rates of energy dissipation in granular bars composed of face-centered cubic arrays of spheres. Experimental results indicate a close agreement between the theoretical and experimental values of wave velocity. However, as in previous experiments with single contacts, the rate of energy dissipation is found to be proportional to the square of the maximum tangential contact force rather than to the cube, as predicted by the theory for small amplitudes.

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.

Epitaxial Growth of fee Fe and Cu Films on Diamond

1993 ◽  
Vol 313 ◽  
Author(s):  
D.P. Pappas ◽  
J.W. Glesener ◽  
V.G. Harris ◽  
J.J. Krebs ◽  
Y.U. Idzerda ◽  
...  
Keyword(s):  
Room Temperature ◽  
High Energy ◽  
Copper Films ◽  
Face Centered Cubic ◽  
Continuous Film ◽  
X Ray ◽  
Cu Films ◽  
Face Centered ◽  
X Ray Absorption ◽  
Oriented Single Crystal

ABSTRACTThe growth of iron and copper films and multilayers on the (100) face of diamond has been achieved and studied by reflection high energy electron diffraction (RHEED), extended x-ray absorption fine structure (EXAFS), ferromagnetic resonance (FMR), and SQUID Magnetometry. RHEED and AES studies show that 2–3 atomic layers (AL) of Fe on C (100) forms a continuous film. The films as deposited at room temperature are disordered, and after a 350° C anneal displays a face-centered cubic structure. Subsequent layers of Cu on this epitaxial Fe film grow as an oriented, single crystal fee film. FMR and SQUID signals have been observed from the Fe films, showing that they are ferromagnetic.

Microstructure and electronic behavior of PtPd@Pt core-shell nanowires

2010 ◽  
Vol 25 (4) ◽  
pp. 711-717 ◽  
Author(s):  
Wei-Qiang Han ◽  
Dong Su ◽  
Michael Murphy ◽  
Matthew Ward ◽  
Tsun-Kong Sham ◽  
...  
Keyword(s):  
Shell Structure ◽  
Phase Transfer ◽  
Core Shell ◽  
Face Centered Cubic ◽  
Edge Structure ◽  
X Ray ◽  
One Step ◽  
Core Shell Structure ◽  
Face Centered ◽  
X Ray Absorption

PtPd@Pt core-shell ultrathin nanowires were prepared using a one-step phase-transfer approach. The diameters of the nanowires range from 2 to 3 nm, and their lengths are up to hundreds of nanometers. Line scanning electron energy loss spectra showed that PtPd bimetallic nanowires have a core-shell structure, with a PtPd alloy core and a Pt monolayer shell. X-ray absorption near edge structure (XANES) spectra reveal that a strong Pt-Pd interaction exists in this nanowire system in that there is PtPd alloying and/or interfacial interaction. Extended x-ray absorption fine structures (EXAFS) further confirms the PtPd@Pt core-shell structure. The bimetallic nanowires were determined to be face-centered cubic structures. The long-chain organic molecules of n-dodecyl trimethylammonium bromide and octadecylamine, used as surfactants during synthesis, were clearly observed using aberration-corrected TEM operated at 80 KV. The interaction of Pt and surfactants was also revealed by EXAFS.

The calculation of stacking fault energies in close-packed metals

1990 ◽  
Vol 5 (10) ◽  
pp. 2107-2119 ◽  
Author(s):  
S. Crampin ◽  
K. Hampel ◽  
D. D. Vvedensky ◽  
J. M. MacLaren
Keyword(s):  
Stacking Fault ◽  
Face Centered Cubic ◽  
Electron Theory ◽  
Simple Scheme ◽  
Cubic Metals ◽  
Interface Unit ◽  
Face Centered ◽  
Experimental Values ◽  
The One ◽  
Stacking Fault Energies

The one-electron theory of metals is applied to the calculation of stacking fault energies in face-centered cubic metals. The extreme difficulties in calculating fault energies of the order of 0.01 eV/(interface unit-cell area) are overcome by applying the Force theorem and using the layer–Korringer–Kohn–Rostoker method to determine the charge density of isolated defects. A simple scheme is presented for accommodating deviations from charge neutrality inherent in this approach. The agreement between theoretical and experimental values for the stacking fault energy is generally good, with contributions localized to within three atomic planes of the fault, but suggest the quoted value for Rh is a significant overestimation.

Time evolution of the structural short-range order during the mechanical milling of Fe–Co–Cu nanocrystalline alloys

1999 ◽  
Vol 14 (10) ◽  
pp. 3882-3888 ◽  
Author(s):  
N. Gay-Sanz ◽  
C. Prieto ◽  
A. Muñoz-Martín ◽  
A. de Andrés ◽  
M. Vázquez ◽  
...  
Keyword(s):  
Time Evolution ◽  
Nanocrystalline Alloys ◽  
Second Step ◽  
Local Order ◽  
Face Centered Cubic ◽  
Processing Times ◽  
Cu Alloy ◽  
The Face ◽  
Face Centered ◽  
X Ray Absorption

The local order around Fe, Co, and Cu atoms was investigated by extended x-ray absorption fine structure spectroscopy in Fe–Co–Cu nanocrystalline alloys prepared by mechanical alloying. In order to study the time evolution of the alloying process, Fe30Co20Cu50 samples were studied after several processing times. The analysis of the data shows that, in a first step, a binary Co–Cu alloy is formed, but iron remains separate in the form of nanocrystals with a high defect concentration. Afterwards, in a second step, the final ternary Fe–Co–Cu alloy with the face-centered-cubic structure is obtained.

scholarly journals A METHOD FOR CALCULATION OF MORSE POTENTIAL FOR FCC, BCC, HCP CRYSTALS APPLIED TO DEBYE-WALLER FACTOR AND EQUATION OF STATE

2007 ◽  
Vol 14 (1) ◽  
pp. 7 ◽  
Author(s):  
NGUYEN VAN HUNG
Keyword(s):  
Fine Structure ◽  
Equation Of State ◽  
Lattice Constant ◽  
Morse Potential ◽  
Waller Factor ◽  
X Ray ◽  
Debye Waller Factor ◽  
X Ray Absorption ◽  
Analytical Expressions ◽  
Potential Parameters

Analytical expressions for the Morse potential parameters for fcc, bcc and hcp crystals have been developed. They contain the energy of sublimation, the compressibility and the lattice constant. Numerical results for Cu (fcc), W (bcc) and Zn (hcp) agree well with the measured values. Debye-Waller factors in X-ray absorption fine structure (XAFS) and equation of state computed using the obtained Morse potential parameters agree well with the experimental results.

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