Electron transport in liquid metals and alloys (original) (raw)
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Electrical transport properties of the liquid AlCu alloys
Journal of Non-Crystalline Solids, 1990
The electrical resistivity p and the thermoelectric power S have been measured for the liquid AI-Cu alloys, from the liquidus to 1300°C, in the whole phase diagram. The resistivity isotherms show one maximum at about 25 at. % A1, which is correctly interpreted by the t-matrix formalism, in the framework of the Faber-Ziman theory. The thermopower decreases abruptly in the range of 20-40 at. % A1, when A1 is added, but this variation cannot be explained by the nearly free electron model.
Theory of Transport Properties of Liquid Non-Simple Metals in the Effective Medium Approximation
Le Journal de Physique Colloques, 1980
Theory of transport properties of structurally disordered systems is formulated based on the tight binding model. The expressions for the conductivity tensors including nonorthogonality of atomic orbitals are given in quite general form with some numerical work. The extension of EMA to the electronic transport is made, and its application to liquid transition metals is discussed.
Summary of New Insight into Electron Transport in Metals
2021
This paper gives a summary of a new insight into basic electron transport characteristics in crystalline elemental metals. The general expressions based on the Fermi-Dirac distribution of the effective density of the randomly moving electrons, their diffusion coefficient, drift mobility, and other characteristics, including the Einstein relation between diffusion coefficient and drift mobility, are presented. It is shown that the creation of the randomly moving electrons due to lattice atom vibrations produces the same number of electronic defects, which cause scattering of the randomly moving electrons and related transport characteristics.
Electrons in non-crystalline metals ?Still a challenging problem
Zeitschrift f�r Physik B Condensed Matter, 1987
The following aspects of the electronic properties of liquid and amorphous metals are studied: (i) density of states of polyvalent liquid metals by means of finite cluster calculations, (ii) the Hall coefficient of simple metals by the use of a generalised transport equation, (iii) the effect of multiple scattering on the electrical resistivity. Measuring electronic densities of states (DOS) and electrical transport coefficients in liquid and amorphous metals is an everyday activity of the Basel solid state group. Therefore any condensed matter theoretician working there is exposed to the question how to calculate such quantities in a simple but well founded theoretical framework. It is the purpose of this contribution to summarize some recent calculcations aiming at a better understanding and a more quantitative description of the electronic properties in non-crystalline metals-a fascinating problem of condensed matter physics on which the first author has had many stimulating discussions with H. Thomas.
Physical Review B, 1989
In the metallic regime of several a-Nl "M and a-T& M alloys, the concentration dependence of the electrical resistivity p can be approximated by d lnp= a*de, where a" is constant for a given alloy and g=x /(1x). N and T stand for a transition metal with completely and incompletely occupied d bands, respectively, and M stands for a metalloid element. If, in the alloy, phase separation is realized, there is electron redistribution between the two phases A and 8. For aN , M"alloys this can be described by dn =-Pnd g with g=xs /X", where n is the electron density in the conduction band (CB) formed by the A phase. X~and X& are the fractions of the A and 8 phases having the average concentrations x"and x~, respectively. P depends on the average potential difference between the A and 8 phases. 8 is the phase with the deeper average potential. Part of the electrons in the 8 phase occupies the valence band (VB) formed by the 8 phase. Another part occupies trap states (as far as available below EF), leading to electron localization. The electron redistribution leads to long-range electron-density fluctuations expressed by 5n =11+()(no n);no is the total s and p valence-electron concentration. Under certain conditions both CB and VB can contribute to the electronic transport.dn =Pn dg is expected to apply also to a T, "M, alloys , where the electron redistribution can enclose part of the d electrons as well. Positive Hall coeScients are expected, when both the VB has "hole" conductivity, and this contribution dominates compared with those of the CB. Activation of electrons from the 8 to the A phase with increasing temperature can lead to a negative temperature coefticient of p.
Electronic transport properties of liquid zinc and zinc–germanium alloys: Theory versus experiment
Journal of Non-crystalline Solids, 2010
The electrical resistivity and the absolute thermoelectric power of liquid zinc, germanium, and zinc–germanium alloys have been measured as a function of temperature by 10 at.% steps between pure zinc and 70 at.% of germanium. The electronic transport properties of the pure liquid metals and alloys are evaluated in the framework of the extended Faber–Ziman theory using a single-site t-matrix. Different muffin-tin potentials are constructed using Hartree Fock and density functional theory (LDA and GGA), to interpret the electron–ion interaction. This formalism explains the anomalous temperature dependence of both the resistivity and the positive absolute thermoelectric power (ATP) of liquid zinc. Concerning the experimental first peak asymmetry of germanium and zinc, the static structure factors cannot be reproduced with hard spheres. They are better described for both pure metals and alloys by a square well pair potential.
Physical Review B
An approach previously developed for the calculation of transport coefficients via the Mott relations is applied to the calculation of finite temperature transport properties of disordered alloys-electrical resistivity and the electronic part of thermal conductivity. The coherent potential approximation (CPA) is used to treat chemical disorder as well as other sources of electron scattering, i.e. temperature induced magnetic moment fluctuations and lattice vibrations via the alloy analogy model. This approach, which treats all forms of disorder on an equal first principles footing, is applied to the calculation of transport properties of a series of face-centered crystal cubic (fcc) concentrated solid solutions of the 3d-transition metals Ni, Fe, Co and Cr. For the nonmagnetic alloys, Ni 0.8 Cr 0.2 , and Ni 0.33 Co 0.33 Cr 0.3 the combined effects of chemical disorder and electron-lattice vibrations scattering result in a monotonic increase in the resistivity as a function of temperature from an already large, T=0, residual resistivity. For magnetic Ni 0.5 Co 0.5 , Ni 0.5 Fe 0.5 , Ni 0.33 Fe 0.33 Co 0.33 , whose residual resistivity is small, additional electron scattering from temperature induced magnetic moment fluctuations results in a further rapid increase of the resistivity as a function of temperature. The electronic part of the thermal conductivity in nonmagnetic, Ni 0.8 Cr 0.2 , and Ni 0.33 Co 0.33 Cr 0.33 , monotonically increases with temperature. This behavior is a result of the competition between a reduction in the conductivity due to electron-lattice vibrations scattering and temperature induced increase in the number of carriers. In the magnetic alloys, electron scattering from magnetic fluctuations leads to an initial rapid decrease in thermal conductivity until this is overcome by an increasing number of carriers at temperatures slightly below the Curie temperature. Similar to the resistivity above T C , the electronic part of the thermal conductivities are close to each other in all alloys studied.
The Inhomogeneous Transport Regime and Metal-Nonmetal Transitions in Disordered Material
Le Journal de Physique Colloques
Rbum6.-Nous avanqons une representation physique pour les changements apparemment continus dans la structure electronique et les proprietks de transport, observes au cours des transitions metal-non metal, se produisant dans les nombreux materiaux dksordonnes. Des deformations structurales ayant pour origine des fluctuations de densite, des modifications de liaisons, la formation de composes ou d'agglomerats, peuvent se traduire par une non-homogen6it6 microscopique locale dans la structure Clectronique de tels mattriaux. Quand la courte distance de correlationde Debyepour les fluctuations est suffisamment grande, celles-ci peuvent Ctre considerees comme statistiquement indkpendantes. De plus en prenant les phases electroniques au hasard, a 1'6chelle de variation de la configuration locale, on peut definir une structure 6lectronique locale et des fonctions locales approprikes. Finalement quand les effets quantiques produits par effet tunnel, et quand les corrections d'energie cinetique sont petits, I'image semi-classique est applicable. En consequence nous pouvons considerer un regiment de transport non homogene dans lequel des effets de percolation se traduisent par un changement continu des proprietes de transport. Une version generaliske de la thCorie du milieu effectif pour la conductivite thermique, l'effet Hall, et le pouvoir thermoelectrique, a Bt B utilisCe pour analyser plusieurs classes de materiaux subissant une transition continue metal-non metal. Une application detaillee de la thkorie est presentee pour des systemes a un constituant tels que Hg liquide ktendu et Te liquide, ainsi que pour des systemes binaires tels que alliages mktalliques et solutions metal-ammoniaque.
On the study of electrical transport properties of some liquid metals by pseudopotential method
Our recently evolved pseudopotential is used to study the electrical transport properties such as electrical resistivity (ρ), thermal conductivity (σ) and thermoelectric power (TEP) of some monovalent (Li, Na, K, Rb, Cs), divalent (Mg, Zn, Ca) and polyvalent (Al, Ga, In, Pb, Sn, Bi, Sb) liquid metals. The model potential theory in conjunction with Ziman, mean free path, tmatrix, and Kubo models are implemented in the above-mentioned work for the first time. The Taylor's local field correction function (T) is taken for observing the exchange and correlation effect with one component plasma (OCP) structure factor method of liquid metals with Hartree dielectric function (H). The presently computed findings are extremely comparable with available data, either theoretical or experimental results that exist in the literature.
Transport phenomena in liquid metals
1976
The primary objective of this research is to study diffusion in liquid metals both theoretically and experimentally by the shear cell method. During the past year, the experimental apparatus has been fabricated, assembled and tested. Diffusion coefficients are presently being measured for the binary system mercury-zinc diffusing into the same alloy. A modified shear cell has been developed to measure the diffusion coefficients of metals with high melting points. It will be tested by measuring diffusion coefficients for thallium at high temperatures. Because of insufficient experimental data, reporting of diffusion coefficient will be delayed until the final report is written. A theoretical diffusion equation has been developed along the lines of a modified small fluctuation theory. It has proven to be successful for predicting self-diffusion coefficients. The Scientific collaborators involved in the research are David D. Arnold and John E. Popielarczyk. Both are candidates for the Master of Chemical Engineering degree and they will each write a thesis dealing with liquid metal diffusion.