REVIEW ARTICLE: Glassy metals

Electronic structure of metallic glasses

A discussion is given of the electrical properties of liquid transition metals and of liquid alloy systems such as Ge-Co. It is suggested that the model of Evans, Greenwood and Lloyd (1971) is valid for the latter, even for quite high concentrations of the transition metal, but that for pure liquid transition metals a different model similar to that used for crystals is appropriate, involving s—d transitions and with different mean free paths for s—p and for d electrons. In this model the resistivity does not depend much on the structure factor, so a small change of resistivity on melting and a change of [sgrave] with T such that d In[sgrave]/dT |Da 1/T is predicted. It is pointed out, however, that electron-electron collisions may make a large contribution to the resistivity and to d In σ/dT. A discussion is given of some features of the Ge-Co and Ge-Fe liquid alloys investigated by. Busch and his collaborators; it is suggested that the temperature-dependence of the resistivity may be due to a K...

The electrical resistivity of liquid transition metals

X-ray diffraction patterns have been obtained from molten silicon and germanium near the melting point. In both cases the structure factor was a low first peak maximum with a small hump on its high angle side in contrast with those of simple molten metals such as sodium and aluminum. It was also found that the pair correlation functions for these molten elements are characterized by a low peak maximum which follows the usual first peak maximum corresponding to the nearest neighbour distance. The electrical resistivity and thermoelectric power have been calculated on the Ziman theory using thet-matrix of muffin-tin potential based on the structural data observed in this work. Good agreement was found in most cases.

Structure of molten silicon and germanium by X-ray diffraction

Publisher Summary During the past decade, there has been an increasing interest in the properties of noncrystalline conductors such as liquid metals, metallic vapors in the critical region, metal-ammonia solutions, and vitreous and amorphous semiconductors. The strict periodicity or long-range order of the atomic arrangement—the basic assumption in solid state theory—is lost in these materials. The noncrystalline state influences mainly the electronic transport properties. Liquid metals are best suited for the investigation of the noncrystalline state because of their well-defined atomic distribution and because of the good reproducibility of the experimental results. However, many experimental difficulties, such as those associated with the application of high temperatures and the effect of corrosion, are encountered in their study. This chapter summarizes the experimental situation of the electronic and magnetic properties of liquid normal, transition, and rare earth metals and their alloys. The experimental data are compared with the results of recent theories which give a possible understanding. But the main aim of this chapter is to make the results known to a larger community and to initiate critical remarks regarding the often very simple models that have been employed. Furthermore, it would be desirable to attain new explanations and detailed comparisons with the explanations of the same effects in the solid state. Throughout this chapter the differences and similarities between the solid and liquid state are emphasized. The section on liquid normal metals is a summary of well-established experimental data and theoretical explanations.

Electronic Properties of Liquid Metals and Alloys

A simple nearly free electron model for the electrical resistivity of liquid noble and transition metals and their alloys is presented. The scattering is described in terms of the phase shifts of muffin tin potentials constructed for the liquids.

http://iopscience.iop.org/article/10.1088/0305-4608/2/4/015/pdf

A simple muffin tin model for the electrical resistivity of liquid noble and transition metals and their alloys

The electrical resistivities, rho , of Eu, Yb and Ba have been measured at high temperatures. In solid Yb and Ba rho varies linearly with temperature. This is contrary to some previous results. Both metals show a large percentage increase of rho on melting. The temperature dependence of rho in Eu is nonlinear and there is a smaller percentage change on melting. The resistivities of liquid Eu and Ba are larger than those of any other liquid metals. Negative temperature coefficients of resistivity are observed for all three metals in the liquid state. These results and those obtained in our earlier measurements on alloys of rare earth metals are discussed in the context of existing theories. The authors suggest that even in the liquid rare earth metals and their alloys an interpretation involving the liquid structure factors and the effective valences of the components may still provide a reasonable qualitative explanation of the behaviour of the resistivity. The occurrence of negative temperature coefficients in other disordered metallic systems is also commented on.

http://iopscience.iop.org/article/10.1088/0305-4608/6/8/011/pdf

H. U. Kunzi

Papers

A simple muffin tin model for the electrical resistivity of liquid noble and transition metals and their alloys

Negative temperature coefficients of electrical resistivity: the divalent liquid metals Eu, Yb and Ba