Temperature-evolution of structure and diffusion properties of liquid transition metals

Temperature evolution of the structure of liquid 3d transition metals: MD study

The results of a comparative analysis of experimental data for the equilibrium properties and characteristics of liquid alkaline earth (magnesium, calcium, strontium), alkaline (lithium, sodium, potassium) and transition metal groups: elements of the subgroups of nickel (Ni, Pd, Pt) and copper (Cu, Ag, Au) near their melting points are presented. Reduced spatial r/rm = rkm /2π and time scales, in which km is the first peak position of the static structure factor S(k) and β = 1/kBT is the inverse temperature, are introduced as the basis for the law of corresponding states. Based on these scale transformations and x-ray diffraction analysis, it was found that the groups of liquid alkaline, alkaline earth, and transition metals are described by universal r- and k- dependencies. It has been established that the dispersion law of longitudinal polarization ωc (k), given in accordance with these scale relations, for elements of groups of liquid alkaline, alkaline earth and transition metals has a single universal character. An analysis of the properties of three groups (alkaline, alkaline earth and transition) liquid metals using scale transformations shows that the law of the corresponding states is valid for these substances.

Atomistic simulation of self-diffusion and interfacial diffusion of liquid lead

We report about molecular dynamics simulations on a virtually shared-memory parallel computer (KSR1-32). Applications comprise massive runs of several nanoseconds simulation-time with models using nearest-neighbour pair-interactions in the study of the dynamics close to the glass transition, and modelling of the atomistic structure of amorphous and liquid metals, using more involved interaction-potentials. Satisfactory parallelization, optimized to small sample sizes, may be achieved in both types of simulations.

Ab initio molecular dynamics for liquid metals

Surface Chemistry of Gallium-Based Liquid Metals

Chemical-ordering in metallic liquid alloys affects important structural, thermodynamic, and dynamical factors governing the kinetics of the glass formation process and the glass-forming ability. The present study on Zr50Cu50, Zr50Cu45Al5, and Zr50Cu45Ag5 metallic glass-forming liquids reveal that minor addition of Al/Ag in Zr50Cu50 leads to different chemical short-range orders due to the hetero-coordination tendency of Al in Zr50Cu45Al5 and homo-coordination tendency of Ag in Zr50Cu45Ag5. Different chemical short-range ordering causes qualitatively different topological short-range orders in the two ternary alloys. Results of inherent structure energy and excess entropy indicate modification of the potential energy landscape such that the local minima (metabasins) on the landscape of Zr50Cu45Al5 become deeper and less rugged, whereas the metabasins become shallower and more rugged in Zr50Cu45Ag5. Single-particle dynamics investigations clearly demonstrate the effect of difference in the chemical-ordering, topological short-range order, and the potential energy landscape on the atomic diffusion, structural relaxation, and dynamic heterogeneities in the ternary alloys. It signifies that the dynamics of the studied glass-forming alloys is closely linked with the structure and thermodynamics. The study also provides a very useful insight of the correlation between the chemical-ordering and the short-time dynamical features in the studied metallic glass-forming liquids.

The atomic-level structures of liquids and glasses are amorphous, lacking long-range order. We characterize the atomic structures by integrating radial distribution functions (RDF) from molecular dynamics (MD) simulations for several metallic liquids and glasses: Cu46Zr54, Ni80Al20, Ni33.3Zr66.7, and Pd82Si18. Resulting cumulative coordination numbers (CN) show that metallic liquids have a dimension of d = 2.55 +/- 0.06 from the center atom to the first coordination shell and metallic glasses have d = 2.71 +/- 0.04, both less than 3. Between the first and second coordination shells, both phases crossover to a dimension of d = 3, as for a crystal. Observations from discrete atom center-of-mass position counting are corroborated by continuously counting Cu glass- and liquid-phase atoms on an artificial grid, which accounts for the occupied atomic volume. Results from Cu grid analysis show short-range d = 2.65 for Cu liquid and d = 2.76 for Cu glass. Cu grid structures crossover to d = 3 at {\xi}~8 {\AA} (~3 atomic diameters). We study the evolution of local structural dimensions during quenching and discuss its correlation with the glass transition phenomenon.

The structure and effective pair potential of liquid manganese near the melting point

Calculation of surface entropy of liquid transition and noble metals

The basic concepts for calculating interatomic potentials for metals and alloys, and their application to the calculation of the atomic and the electronic structure of liquid and amorphous metals and alloys, are discussed.

ABSTRACTWe discuss various aspects of calculating the electronic structure of liquid and amorphous metals using the recursion method and the tight-binding linear muffin-tin orbitals (TB-LMTO) basis. Resistivity calculations for such systems based on the Kubo-Greenwood formula and the TB-LMTO-recursion method are presented and compared with similar calculations based on the linear combination of atomic and atomic-like orbitals (LCAO) and the chemical pseudopotential approach. Results for amorphous Fe and Co and liquid Hg, Pd, and some 3d transition metals are presented. Sources of error in the calculation and ways to improve upon the present calculations are discussed.

Gallium-based room-temperature liquid metals have enormous potential for realizing various applications in electronic devices, heat flow management, and soft actuators. Filling narrow spaces with a liquid metal is of great importance in rapid prototyping and circuit printing. However, it is relatively difficult to stretch or spread liquid metals into desired patterns because of their large surface tension. Here, we propose a method to fabricate a particle-based porous material which can enable the rapid and spontaneous diffusion of liquid metals within the material under a capillary force. Remarkably, such a method can allow liquid metal to diffuse along complex structures and even overcome the effect of gravity despite their large densities. We further demonstrate that the developed method can be utilized for prototyping complex three-dimensional (3D) structures via direct casting and connecting individual parts or by 3D printing. As such, we believe that the presented technique holds great promise for the development of additive manufacturing, rapid prototyping, and soft electronics using liquid metals.

Measured structure factors and entropies are used to obtain, very directly, the electronic contributions to the entropies and hence the densities of states at the Fermi levels in some liquid transition metals.

A simple theory is presented for the electrical conductivity of liquid metals with d electrons. Taking into account the s-d hybridization and treating the d electrons within the tight binding approximation, the authors study in particular the d electron contribution to the electrical resistivity. Numerical results obtained for a simple band model indicate important d electron contribution to the electrical resistivity. Numerical results obtained for a simple band model indicate important d electron contributions to the electrical conductivity in liquid transition and rare earth metals. One finds that for a nearly half filled band the d electron contribution to the electrical conductivity may be of the same order of magnitude as the one due to s electrons. As the d band becomes more than half filled or more than half empty the d electron contribution to the electrical conductivity decreases.