An embedded atom analysis of Au and Pt substitutional atoms in Ni

1989 ◽  
Vol 4 (3) ◽  
pp. 552-556 ◽  
Author(s):  
P. Ruppa ◽  
C. M. Gilmore
Keyword(s):  
Radial Distance ◽  
Crystallographic Direction ◽  
Size Difference ◽  
Heat Of Mixing ◽  
Spherically Symmetric ◽  
Elastic Analysis ◽  
Energy Increase ◽  
Strain Fields ◽  
Embedded Atom ◽  
Substitutional Atom

The Embedded Atom Model (EAM) was utilized to analyze the energy and strain surrounding Au and Pt atoms substituted into a Ni crystal. Au substituted into Ni has a large positive size difference and a positive heat of mixing; Pt substituted into Ni has a large positive size difference and a negative heat of mixing. The EAM predicted highly anisotropic strain fields around the substitutional atom with large positive strains in the [110] direction and small or negative strains in the [100] and [111] directions. This is in contrast to the normal assumption that the strain around a substitution atom is spherically symmetric. The cohesive energy of the atoms around the substitutional atom was found to depend upon the crystallographic direction relative to the substitutional atom in addition to the radial distance from the substitutional atom. The EAM predicted an energy increase for Au substituted into Ni and an energy decrease for Pt substituted into Ni. The EAM results were compared with an elastic analysis.

Strain Fields around Dislocation Cores Studied by Analyzing Coordinates of Discrete Atoms

2015 ◽  
Vol 817 ◽  
pp. 712-718
Author(s):  
Yu Fei Shao ◽  
Xin Yang ◽  
Jiu Hui Li ◽  
Xing Zhao
Keyword(s):  
Strain Field ◽  
Strain Tensor ◽  
Dislocation Core ◽  
Dislocation Model ◽  
Embedded Atom Method ◽  
Strain Fields ◽  
Embedded Atom ◽  
Lattice Symmetry ◽  
Dislocation Pair ◽  
Theoretical Predictions

Dislocation core structures in Au and Cu crystals are investigated by means of quasicontinuum simulations combined with the embedded atom method potentials. A dislocation pair in a graphene sheet, which is observed by Warner et al. experimentally, is also analyzed in the present work. The strain fields around these dislocations in Au, Cu, and graphene crystals are calculated by analyzing the coordinates of discrete atoms, which is a strain tensor calculation method proposed by Zimmerman et al., and compared with theoretical predictions based on Foreman dislocation model. It is shown that the strain fields given by Zimmerman theory are completely suitable for describing the dislocation core structures of Au, Cu and graphene crystals. However, compared with the results of Au and Cu, the Zimmerman strain field in the vicinity of graphene dislocation core is a little less accurate, possibly due to the effect of lattice symmetry of graphene, which needs to be clarified in the future study.

scholarly journals Similarity solutions of the steady state cosmic-ray equation of transport

1976 ◽  
Vol 19 (4) ◽  
pp. 432-451 ◽  
Author(s):  
G. M. Webb
Keyword(s):  
Diffusion Coefficient ◽  
Steady State ◽  
Radial Distance ◽  
Cosmic Ray ◽  
Analytic Solutions ◽  
State Equation ◽  
Similarity Solutions ◽  
Symmetric Model ◽  
Spherically Symmetric ◽  
Special Cases

AbstractSimilarity solutions of the steady-state equation of transport for the distribution function F0 of cosmic rays in the interplanetary region are obtained by theuse of transformation groups. The solutions are derived in detail for a spherically-symmetric model of the interplanetary region with an effective radial diffusion coefficient κ = κ0(p)rb with r the heliocentric radial distance. p the particle momentum, κ0(p) an arbitary function of p, and the solar wind velocity is radial and of constant speed V. Solutions for which the similarity variable η is a function of r only are also derived; these are of particular impoartance when the F0 is specified on a boundary of given radius. Non spherically-symmetric solutions can also be obtained by group methods and examples of such solutions are listed, without derivation, for the equation of transport incorporating the effects of anisotropic diffusion (diffusion coefficient κ1 in the radial direction and κ2 normal to it). The solutions are the most extensive steady-state analytic solutions yet obtained, and contain previous analytic solutions as special cases.

Improved prediction of heat of mixing and segregation in metallic alloys using tunable mixing rule for embedded atom method

2017 ◽  
Vol 25 (8) ◽  
pp. 085011 ◽  
Author(s):  
Srikanth Divi ◽  
Gargi Agrahari ◽  
Sanket Ranjan Kadulkar ◽  
Sanjeet Kumar ◽  
Abhijit Chatterjee
Keyword(s):  
Metallic Alloys ◽  
Heat Of Mixing ◽  
Embedded Atom Method ◽  
Mixing Rule ◽  
Embedded Atom

scholarly journals ENERGY ASSOCIATED WITH CHARGED DILATON BLACK HOLES

1996 ◽  
Vol 05 (03) ◽  
pp. 251-256 ◽  
Author(s):  
A. CHAMORRO ◽  
K.S. VIRBHADRA
Keyword(s):  
Black Holes ◽  
Energy Distribution ◽  
Total Energy ◽  
Free Parameter ◽  
Coupling Parameter ◽  
Radial Distance ◽  
Maxwell Field ◽  
Spherically Symmetric ◽  
Dilaton Black Holes

It is known that certain properties of charged dilaton black holes depend on a free parameter β which controls the strength of the coupling of the dilaton to the Maxwell field. We obtain the energy associated with static spherically symmetric charged dilaton black holes for arbitrary value of the coupling parameter and find that the energy distribution depends on the value of β. With increasing radial distance, the energy in a sphere increases for β=0 as well as for β<1, decreases for β>1, and remains constant for β=1. However, the total energy turns out to be the same for all values of β.

scholarly journals Effective gravitational mass of the Ayón-Beato and García metric

2015 ◽  
Vol 30 (25) ◽  
pp. 1550120 ◽  
Author(s):  
A. K. Sinha ◽  
G. K. Pandey ◽  
A. K. Bhaskar ◽  
B. C. Rai ◽  
A. K. Jha ◽  
...  
Keyword(s):  
Electromagnetic Field ◽  
Electric Charge ◽  
Radial Distance ◽  
Gravitational Mass ◽  
Spherically Symmetric ◽  
Einstein’S Equations ◽  
Einstein's Equations ◽  
Adm Mass

In this paper, we calculate the effective gravitational mass of Ayón-Beato and García (AG) regular (nonsingular) static spherically symmetric asymptotically Minkowskian metric that is a solution to Einstein’s equations coupled with a nonlinear electromagnetic field. The effective gravitational mass is negative, zero, or positive that depends on the ratio of magnitude of electric charge to the ADM mass and the ratio of the radial distance to the ADM mass. As expected, at large values of radial distance, our result gives effective gravitational mass of the Reissner–Nordström metric.

Microstructure of Zr3Al After 2 MeV Proton Bombardment

1992 ◽  
Vol 279 ◽  
Author(s):  
F. C. Chen ◽  
A. J. Ardell ◽  
D. F. Pedraza ◽  
R. A. Buhl
Keyword(s):  
Low Temperature ◽  
Dark Field ◽  
Spherically Symmetric ◽  
Long Range Order ◽  
Proton Bombardment ◽  
Strain Fields ◽  
Black Spots ◽  
Ordered Intermetallic ◽  
Higher Doses ◽  
Mev Protons

ABSTRACTThe ordered intermetallic Ll2 alloy Zr3Al was irradiated with 2 MeV protons at -124 °C to fluences up to 2 × 1015 H+/mm2 and at 250 °C to fluences up to 1 × 1015 H+/mm2. Defects with spherically symmetric strain fields were produced at both irradiation temperatures. They are of interstitial character at -124 °C and vacancy character at 250 °C. Disordering is induced at -124 °C, whereas irradiating at 250 °C initially lowers, then slightly raises, the degree of long-range order above its unirradiated value. Additional defects that appear as black spots were imaged using superlattice reflections in dark field. For the low-temperature irradiations they were seen at all doses, but were present at only the lowest close for the high-temperature irradiations. They are probably disordered zones, although some of the zones may be amorphous at the higher doses in the low-temperature irradiations.

scholarly journals Horizon straddling ISCOs in spherically symmetric string black holes

2015 ◽  
Vol 24 (11) ◽  
pp. 1550086 ◽  
Author(s):  
Parthapratim Pradhan
Keyword(s):  
Black Holes ◽  
Event Horizon ◽  
Circular Orbit ◽  
Null Geodesic ◽  
Radial Distance ◽  
Spherically Symmetric ◽  
Heterotic String Theory ◽  
Charged Black Holes ◽  
Stable Circular Orbit ◽  
Extremal Limit

The causal geodesics in the equatorial plane of a static extremal charged black holes in heterotic string theory is examined with regard to their geodesic stability and compared with similar geodesics in the nonextremal situation. Extremization of the effective potential for timelike and null circular geodesics implies that in the extremal limit, the radius of ISCO (Inner-most Stable Circular Orbit) (r ISCO ), circular photon orbit (CPO) (r ph ) and marginally bound circular orbit (MBCO) (r mb ) are coincident with the event horizon (r hor ) i.e. r ISCO = r ph = r mb = r hor = 2M. Since the proper radial distance on a constant time slice both in Schwarzschild and Painlevé–Gullstrand (PG) coordinates become zero, thus these three orbits indeed coincide with the null geodesic generators of the event horizon. This strange behavior is quite different from the static, spherically symmetric extremal Reissner–Nordstrøm (RN) BH.

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