Prediction of the Metal−Non-Metal Transition Using the Linear Isotherm Regularity

Abstract

A gradual transition from metallic to non-metallic occurs when density decreases. In the present work a thermodynamic equation of state namely the linear isotherm regularity, LIR, has been used to predict this transition. While the transition is occurring, a number of changes in the liquid structure happen and therefore a deviation from the linearity predicted by the LIR for a single-phase system is observed. The statistical mechanical theory of mixture, along with the LIR, has been used to derive an appropriate equation of state for the mixture of metal and non-metal, after the beginning of the transition. The derived equation of state is found to be (Z − 1)v 2 = a + bρ2 + cρ. In our approach only the experimental p−v−T data are required to predict such a transition for liquids Cs, Rb, Na, and Hg. The predictions are in agreement with experimental observations. It is also shown that the transition is neither first order nor second order.

Linear Exp-6 Isotherm for Compressed Molten Cesium over the Whole Liquid Range Including Metal−Nonmetal Transition and Tc

“…They finally argued that the linear isotherm persists at any temperature unless the densities of liquid alkalis are smaller than their characteristic density limits at which n-mers are being formed and, thus, the quadratic behavior is started. 6 The density limit corresponds to the density below which a marked decrease in the electric conductivity in liquid alkali metal is occurred, 1.21 g/cm 3 for Cs, for instance. 3 Favoring this viewpoint, we will pursue the problem of the deterioration of the linearity 4 of the linear isotherms that are observed as a result of metal-nonmetal transition in the expanded liquid alkali metals close to critical temperature.…”

A new equation of state for molten alkali metal alloys

“…Using the values of C and D parameters along with the Eqs. (27)(28)(29)(30)(31)(32), these derived properties of liquid alkali metal alloys can be calculated at any thermodynamic state point. Isobaric expansion coefficient may be calculated from the following expression:…”

“…The variations of ε and r m with temperature for liquid metals and normal fluids have been already investigated [32][33][34][35][36][37]. The values of r m calculated from Eq.…”

“…1 on which up to 1350 K, r m increases linearly with temperature and bends upward thereafter. According to the literature [32][33][34], there is a change in the cesium structure after 1350 K, the temperature on which the metal-nonmetal transition occurs. Fig.…”

Common compression factor and bulk modulus quiescence points of liquid cesium

“…This feature is attributed to the characteristic of potential function used to derive the equation of state(2) [20,21]. Notice that the transition to a nonmetallic fluid onsets at the range, indicating the influence of liquid structure on the transition [12,19].…”