Thermal transport properties of halide solid solutions: Experiments vs equilibrium molecular dynamics

Abstract

The composition dependence of thermal transport properties of the (Na,K)Cl rocksalt solid solution is investigated through equilibrium molecular dynamics (EMD) simulations in the entire range of composition and the results are compared with experiments published in recent work [Gheribi et al., J. Chem. phys. 141, 104508 (2014)]. The thermal diffusivity of the (Na,K)Cl solid solution has been measured from 473 K to 823 K using the laser flash technique, and the thermal conductivity was deduced from critically assessed data of heat capacity and density. The thermal conductivity was also predicted at 900 K in the entire range of composition by a series of EMD simulations in both NPT and NVT statistical ensembles using the Green-Kubo theory. The aim of the present paper is to provide an objective analysis of the capability of EMD simulations in predicting the composition dependence of the thermal transport properties of halide solid solutions. According to the Klemens-Callaway [P. G. Klemens, Phys. Rev. 119, 507 (1960) and J. Callaway and H. C. von Bayer, Phys. Rev. 120, 1149 (1960)] theory, the thermal conductivity degradation of the solid solution is explained by mass and strain field fluctuations upon the phonon scattering cross section. A rigorous analysis of the consistency between the theoretical approach and the EMD simulations is discussed in detail.

Study of the Partial Charge Transport Properties in the Molten Alumina via Molecular Dynamics

“…Nonetheless, here we clearly claim that in such situations, EMD data should be considered as a reference, as the method has already proven its high predictive capability for several dynamic and transport properties for both simple and complex molten ionically bonded systems. 18−22,25 Our calculated ionic conductivities are in good agreement with those of the two models. Both agree well with some data sets for both liquid and undercooled Al 2 O 3 : specifically, those reported by Shpil’rain et al 1 from melting temperature up to 3000 K, and those reported by Elyutin et al 4 below the melting temperature as low as 2050 K. Experimental data reported by Aleksandrov et al 2 and Arkel 6 are much higher than the other data sets and EMD calculations as well.…”

Thermal conductivity of the side ledge in aluminium electrolysis cells: compounds as a function of temperature and grain size

“…for the prediction of the lattice thermal conductivity is illustrated in Figure 1 for CaF 2 (cubic,Fm 3m). This method is detailed extensively in our previous papers [8][9][10][11], here we provide only the main principles.…”

“…The most relevant formulation of Φ ph−ph was originally proposed by Callaway [17,18] and later by Slack [20,21] and relied only on a few key physical properties for its parametrization. Without going into details, which can be found in [8,10,12,19], Callaway and Salck's expression of Φ ph−ph , combined with Eq. 10, gives an expression which can be decomposed into two terms: a materials constants term (M at − Cst.)…”

“…Somoke and Koening (1958): [59], Charavat and Kingery (1957): [60], Slak (1960): [61] It has already been demonstrated that for NaF, LiF, α-Al 3 O 3 , MgO, α-SiC [8] NaCl, KCl [10,11] Li 2 0 [12] the method "Exp." shows a very good predictive capacity.…”

“…To alleviate this lack data, we have developed, for electrically insulating material and semiconductors, a generalized self consistent method [8][9][10][11][12] to predict the Gibbs free energy of solids from 0 K up to the melting temperature and the thermal conductivity from room temperature up to the melting point. The method combines the quasi-harmonic approximation for the density of the lattice vibration energy and from anharmonic Umklapp processes (U-process) for the phonon-phonon scattering at high temperature, approximately above one third of the Debye temperature.…”