The fusion curves of xenon, krypton, and argon

Abstract

The experimental results on the fusion of the heavier rare gases at very high pressures, obtained in the last 20 years, are examined and analysed in conjunction with the measurements made at lower pressures from 1940 onwards. The parameters in the Simon equation for the melting curves of Xe, Kr, and Ar are determined, and the coordinates of a possible high-pressure {s(fcc) + s(hcp) + '} triple-point are identified for each one of these three elements. The enthalpies of transition of the transformations involved are estimated as well as their respective values of the entropies of transition.

Melting at High Pressure: Can First‐Principles Computational Chemistry Challenge Diamond‐Anvil Cell Experiments?

“…As shown in Figure 1, our ab initio melting curve agrees with the smooth fit of Ferreira’s and Lobo’s meta‐analysis9 over the entire pressure and temperature range. For example, at 100 GPa, we compute T m to 4409±132 K; Ferreira and Lobo extrapolate to 4357 to 4451 K 9.…”

“…Herein we report the melting curve of argon predicted from ab initio Monte Carlo simulations of the fcc crystal and liquid phases. Employing accurate analytic many‐body potentials derived from rigorous relativistic electronic structure calculations, we observe corresponding‐state behavior, that is, a Simon law, up to 100 GPa in quantitative agreement with a 2008 meta‐analysis 9. As shown in Figure 1, our simulations exceed the highest pressure experimentally achieved for melting argon.…”

The sublimation of argon, krypton, and xenon

“…In the absence of measured values of these properties, one can try and describe the equilibrium curves through empirical equations. Using this latter procedure, we recently reported on the vapour pressure of radon [2] and on the fusion curves of Xe, Kr, and Ar [3]. In the years of 1960s, Ziegler and co-workers [4][5][6] analysed the experimental sublimation data for argon, krypton, and xenon, and devised a method to conjugate the information available to describe the (solid + vapour) equilibria.…”

“…The points in this figure are experimental, from various sources. The deviation plots in figure 2 elucidate more clearly on the quantitative aspects in this context.After numerically complete forms of equation(2) had been established for the three classical rare gases, the values of D g s H m are easily calculated as functions of temperature by using equation(3). The results obtained at T = 0 K and T = T t are registered in table 5, and the change of D g s H m with temperature is shown infigure 3.…”

The vaporization properties of krypton and xenon

“…In this paper we examine the phase equilibria of rare gases [5][6][7] by assessing here the (vapour + liquid) saturation properties of krypton and xenon, namely the vapour pressure and the orthobaric molar volumes along the entire liquid range. The (derived) values of the enthalpy of vaporization are evaluated at the triple point and at the normal boiling temperature.…”