Temperature dependence of the coefficient of self-diffusion in liquids

The effect of the hydrogen bonding on the magnetic anisotropy of o-halogenobenzoic acids and some derivatives of phenol, namely 2-aminophenol, 2,3-dimethylphenol and 2-methyl-3-bromophenol, is studied. These molecules are of known crystal structures. The crystal susceptibilities (x ₁, x ₂ and x ₃) of each compound were measured. From these measurements and the molecular orientation, the principal molecular susceptibilities (K ₁, K ₂ and K ₃) have been calculated. The observed magnetic data are interpreted in the light of the structures of these molecules and their hydrogen bonding systems.     

The self-diffusion coefficient of liquid methane

Self-diffusion coefficients of methane have been calculated over a wide density range using the method of molecular dynamics. Methane intermolecular interactions were modelled using an m-6–8 potential with coefficients determined from viscosity data for the dilute gas. After adding a contribution to the diffusion coefficient due to the long-time behaviour of the velocity autocorrelation function, agreement with experimental data is within the estimated errors given for both the calculated values and the experimental data.     

Simple model for the calculation of the coefficient of self-diffusion in a liquid

The coefficient of self-diffusion in three-dimensional classical liquid is computed approximately from the hierarchy of kinetic equations for the time-correlation functions (TCF).     

Concentration dependence of nickel diffusion in nickel-cobalt alloys

In the present paper the results of measuring the self-diffusion coefficients for Ni in Ni-Co alloy in the composition interval 0–100 at.% Co, and in the temperature range 1065–1290 °C are given. The measurements have been carried out by the Gruzin method using the radioisotope Ni-63. The curves indicating the concentration dependence of the diffusion coefficients calculated for differentaT _m vaules (T _m is the melting point at a given concentration,a is a number from the interval (0, 1)) are straight lines; this feature has been found in other solid solutions which slightly deviate from regularity as well. It results in simple equations for the concentration dependence of self-diffusion characteristicsD ₀ andH.     

Concentration dependence of the resistivity maximum of Cu-Mn alloys

Comparing over a wide range of compositions the experimentally determined temperatures, T_m, of the maximum of the Mn solute contribution to the resistivity with the values calculated from Larsen's theory, we found no satisfactory agreement within a physically reasonable range of the pertinent parameters. We arrived at similar results when comparing the experimental and the calculated values of the maximum Mn solute contribution as a function of composition.     

Concentration dependence of short-range order parameters in annealed copper-aluminum alloys

The method of diffuse X-ray scattering was used to investigate -CuAl alloys containing between 11.9 and 17.6 at.% aluminum after prolonged stepwise annealing. Analysis of the short-range order coefficients indicated uniform ordering at concentrations up to 15 at.% aluminum and possible departure from uniform ordering in alloys with higher concentrations. It was shown that the structure of the ordered alloy is consistent with the model proposed by Gehlen and Cohen [13].     

Transport in two dimensions. I the self-diffusion coefficient

The Mori formalism is used to study generalized transport coefficients in two dimensions. All finite multilinear products of the single particle density and momentum density comprise the set of the variables in the calculation of the self-diffusion coefficient. A self-consistent equation, which is a non-linear integral equation, is obtained for the leading asymptotic behavior of the generalized self-diffusion coefficient. An asymptotic solution is presented which for small wavevector (k) and frequency (s) behaves like $\text{In}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(s + k}{}^2\text{D)}{}^{\mathrm{?1}}$, where D has the dimensions of a diffusion coefficient. The mean square and mean fourth displacements of a tagged particle are also calculated. The long time behavior of the momentum correlation function exhibits a tail of the form $\text{[t}\text{In}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(t)]}{}^{\mathrm{?1}}$ whose coefficient is dependent of the intermolecular potential.     

On the anomalous temperature dependence of the electrical resistivity in liquid alloys

It is demonstrated that the anomalous temperature dependence of the electrical resistivity, as experimentally reported for liquid binary alloys of simple metals, arises primarily from the significant decrease in the partial localization of the valence electrons on the electronegative component.     

Size dependence of self-diffusion in the hard-square lattice gas

A striking size dependence of the mean-square displacement of diffusing particles in the two-dimensional lattice gas of hard squares has been observed by Monte Carlo simulation. It is shown that the size effect is due to the formation of a stable cage structure in small lattices when the particle concentration is high. The formation of cages is governed by a new type of percolation problem related to bootstrap percolation.     

Understanding the loading dependence of self-diffusion in carbon nanotubes

The influence of flexible walls on the self-diffusion of CH4 in an isolated single walled carbon nanotube, as an example, is studied by molecular dynamics simulations. By simulating the carbon nanotube as a flexible framework we demonstrate that the flexibility has a crucial influence on self-diffusion at low loadings. We show how this influence can be incorporated in a simulation of a rigid nanotube by using a Lowe-Andersen thermostat which works on interface-fluid collisions. The reproduction of the results of a flexible carbon nanotube by a rigid nanotube simulation is excellent.     

Temperature dependence of the self-diffusion tensor of para-azoxyanisole

The temperature dependence of the self-diffusion tensor of the nematic liquid crystal para-azoxy-anisole (PAA) has been measured by a neutron scattering method. It is found that the self-diffusion is anisotropic and that its temperature variation is apparently dominated by variation of the order parameter.     

On the self-diffusion coefficient of the Van der Waals fluid

We have calculated the first non-vanishing correction (∝γ²) to the self-diffusion coefficient D of a Van der Waals fluid, where the attractive forces are characterized by the inverse range γ, taken as a smallness parameter.     

Field dependence of the anomalous Hall effect coefficient of granular alloys with giant Magnetoresistance

It is shown theoretically that the anomalous Hall effect (AHE) coefficient R _s of magnetic granular alloys exhibiting giant magnetoresistance (GMR) depends strongly and, in the general case, nonmonotonically on the magnetic field as a result of the effect of the field on the character of the charge-carrier scattering and the AHE. The experimental data, presented by H. Sato, H. Hemmi, Y. Kobayashi et al., J. Appl. Phys. 76, 6919 (1994), on the field dependence R _s (H) in Co-Ag granular alloys at low temperatures are explained. The presence of a maximum in the field dependence |R _s (H)| in annealed Co-Ag alloys attests to the fact that skew scattering plays a dominant role in the formation of the AHE and that the main carriers of the AHE in these alloys are states whose spin polarization is directed oppositely to the magnetization. The presence of a minimum in this dependence for unannealed samples indicates nonuniformity of the granule size distribution. Pis’ma Zh. éksp. Teor. Fiz. 65, No. 6, 481–484 (25 March 1997)     

Spin-echo measurements of the conduction electrons self-diffusion coefficient in a metal

The principle possibility of spin echo measurements of conduction electron orbital motion parameters is experimentally demonstrated, using metallic lithium as an example.     

A simple spin echo measurement of the anisotropy of the self-diffusion coefficient in a smectic A and B type liquid crystal

The temperature dependence of the self diffusion coefficients D_ along D₆ perpendicular to the molecular director of p-dodecanoyl-benzylidene-p -aminoazobenzene has been investigated in both the smectic A and B regime.