Nguyen Quang Hoc

Elastic Moduli and Elastic Constants of Alloy AuCuSi With FCC Structure Under Pressure

Abstract This paper studies on the dependence of the mean nearest neighbor distance, the Young modulus E, the bulk modulus K, the rigidity modulus G and the elastic constants C11, C12, C44 on temperature, pressure, the concentration of substitution atoms and the concentration of interstitial atoms for alloy AuCuSi (substitution alloy AuCu with interstitial atom Si) with FCC structure by the way of the statistical moment method (SMM). The numerical results for alloy AuCuSi are compared with the numerical results for main metal Au, substitution alloy AuCu, interstitial alloy AuSi, other calculated results and experiments.

Thermodynamic and Elastic Properties of Interstitial Alloy FeC with BCC Structure at Zero Pressure

The analytic expressions for the thermodynamic and elastic quantities such as the mean nearest neighbor distance, the free energy, the isothermal compressibility, the thermal expansion coefficient, the heat capacities at constant volume and at constant pressure, the Young modulus, the bulk modulus, the rigidity modulus, and the elastic constants of binary interstitial alloy with body-centered cubic (BCC) structure, and the small concentration of interstitial atoms (below 5%) are derived by the statistical moment method. The theoretical results are applied to interstitial alloy FeC in the interval of temperature from 100 to 1000 K and in the interval of interstitial atom concentration from 0 to 5%. In special cases, we obtain the thermodynamic quantities of main metal Fe with BCC structure. Our calculated results for some thermodynamic and elastic quantities of main metal Fe and alloy FeC are compared with experiments.

Critical Temperature for Ordered-Disordered Phase Transformation in Cu3Au under Pressure

We use the statistical moment method to study the dependence of the critical temperature for Cu3Au on pressure in the interval from 0 to 30 kbar. The calculated mean speed of changing critical temperature to pressure is 1.8 K/kbar. This result is in a good agreement with the experimental data.

The Nernst effect in layered superconductors under a magnetic field

We calculated the Nernst signal eN, describing the Nernst effect in type-II superconductor in the vortex–liquid regime, by using the time-dependent Ginzburg–Landau (TDGL) equation with thermal noise. The nonlinear interaction term in the TDGL equation is treated within self-consistent Gaussian approximation. The expression of the Nernst signal eN including all the Landau levels is presented in explicit form which is applicable essentially to the whole phase. Our results are compared with the recent experimental data on high-Tc superconductor.

Melting curve of metals Cu, Ag and Au under pressure

In this paper, the dependence of the melting temperature of metals Cu, Ag and Au under pressure in the interval from 0 kbar to 40 kbar is studied by the statistical moment method (SMM). This dependence has the form of near linearity and the calculated slopes of melting curve are 3.9 for Cu, 5.7 for Ag and 6 for Au. These results are in good agreement with the experimental data.

Transport coefficients and Nernst signal of type-II superconductors under magnetic field

In this paper, we have studied the transport properties in two-dimensional superconductors in the frame of the Langevin approach to the time dependent Ginzburg–Landau equation. The electrical and thermoelectric conductivity, resulting from thermal fluctuations of the superconducting order parameter, are computed in the self-consistent Gaussian approximation for an arbitrarily strong electric field and a magnetic field. The Nernst signal, describing the Nernst effect in type-II superconductor under a magnetic field, is also calculated in linear response limit. We obtain analytical expressions for the electrical conductivity, the thermoelectric conductivity and the Nernst signal summing all Landau levels without need to cutoff higher Landau levels to treat an arbitrary magnetic field. Our results indicate that the electrical and thermoelectric conductivity are suppressed in high electric fields and the Nernst signal is in good agreement with experimental data on Bi2Sr2CaCu2O8+δ.

ANALYTIC EXPRESSION OF THERMODYNAMIC QUANTITIES FOR MOLECULAR CRYOCRYSTALS OF NITROGEN TYPEWITH FCC AND HCP STRUCTURES IN HARMONIC, CLASSICAL AND ANHARMONIC APPROXIMATIONS

The analytic expressions of thermodynamic quantities such as the Helmholtz free energy, the internal energy, the entropy, the molar heat capacity at constant volume for molecular cryocrystals of N2 type with face-centered cubic (FCC) and hexagonal close-packed (HCP) structures in harmonic, classical and anharmonic approximations are obtained by combining the statistical moment method (SMM) and the self-consistent field method (SCFM).

Equation of state and thermal expansion of metals with FCC structure: Application to Cu, Al and Ni

The equation of state, the expressions of lattice parameter and thermal expansion coefficient in general form are obtained by the statistical moment method. Applying to Cu, Al and Ni metals, we determine these properties in simple analytic form for each metal. Numerical results for the thermal expansion coefficient of these metals in different temperatures and pressures are in good agreement with experiments.