Structural, vibrational, and transport properties of compound forming liquid Li-Bi alloys

Abstract

Due to the compound forming tendency, some of the liquid metal alloys show anomalous behavior in their physical and chemical properties. Near the compound forming concentration, their electrical resistivity is beyond the metallic values and hence they may be labelled as liquid semiconductors. Lithium-Bismuth is one such system. It shows some interesting features in terms of physical and chemical properties such as departure from nearly free electron theory, very high value of electrical resistivity near the compound forming composition. While dealing with the electrical resistivity of liquid alloys with very high values of electrical resistivity, the famously used approaches such as Faber-Ziman theory and Morgan theory have some limitations. Hence, some modifications in these theoretical formalisms are required in order to reproduce the experimental values of the electrical transport properties. We, in the present work have modeled liquid Li-Bi system using model potential formalism in conjunction with the established theoretical models along with suitable modifications to study structural, elastic and transport properties. In particular, we have treated the effective valence of pure Li and Bi as parameters and we have calculated the phase shifts using model potentials rather than muffin-tin potential. The results are compared with the results of molecular dynamics simulation and other theoretical models. It is observed that the t-matrix formulation in conjunction with the model potential formalism is able to reproduce the correct trends in the electrical resistivity isotherm. Whereas the results of Faber-Ziman and Morgan theory are highly underestimated, the non-metallic behavior near the critical composition can be explained clearly from the present results of electrical resistivity. Further, phonon frequencies and sound velocities are also estimated.