Approach to the Coulomb Contribution of Thermodynamic Properties from the Mean Electrostatic Potential of the Ions in (ZrO₂)_1–x(Y₂O₃)_x

Abstract

Metal oxides with oxygen vacancies are widely used in electrochemical processes at high temperature due to their ionic conductivity. These processes are strongly influenced by the electrostatic potential of the ions because it is closely related to the electrochemical potential. We calculate the partial molecular Coulomb internal energy for different compositions of yttria-stabilized zirconia (YSZ) with molecular dynamics (MD) at different temperatures and zero pressure. On the basis of thermodynamic considerations, we assume that these quantities correspond to the electrostatic potential of ZrO 2 and Y 2 O 3. We also calculate the mean electrostatic potential of the ions and develop a mixing rule between this potential and the electrostatic potential of the molecules. With this mixing rule and following the thermodynamic framework proposed in this study, one can calculate the Coulomb contribution of other thermodynamic properties like the entropy or the Nernst–Planck diffusivities for YSZ-like metal oxides. Furthermore, the methods proposed here can be extended for other electrolyte mixtures.

Impact of Multi-Causal Transport Mechanisms in an Electrolyte Supported Planar SOFC with (ZrO2)x−1(Y2O3)x Electrolyte

“…In this work, we study only YSZ-electrolytes. The doping of Y 2 O 3 in ZrO 2 to form YSZ results in vacancies [46]. This defect formation can be described by the following reaction in Kröger-Vink notation:…”

“…For 1300 K, no cation diffusion in YSZ occurs; i.e., L ZZ = L YY = 0 [52]. Furthermore, Valadez Huerta et al [46] compare their classical MD calculations of the Coulomb energy in YSZ with ab-initio calculations and do not find any substantial differences, concluding that polarization effects can be neglected. With these assumptions, we can write J e O 2− = j/(z * F) and…”

A Diffusivity Study of (Sc2O3)0.1(CeO2)0.01(ZrO2)0.89 between 1100 and 1500 K at Zero Pressure with Molecular Dynamics

“…We select this material because it has a higher ionic conductivity than the standard material for SOFC applications, YSZ. We perform our calculations with the MD package LAMMPS using the methodology reported in our previous work. , We use the Buckingham potential to describe the interatomic contributions with a parametrization from the works of Dwedi and Cormack for the Zr–O and O–O interactions and a parametrization from Lewis and Catlow for the Sc–O and Ce–O interactions. The calculated lattice constant is in agreement with experimental data.…”

“…All of our calculations are strictly classical, and we carry them out using LAMMPS . We use the computation methodology described in our previous works. , For all simulations, periodic boundary conditions apply. We use a cutoff radius for the non-Coulomb contributions of 10 × 10 –10 m. We integrate the Coulomb energy with the Ewald sum using an accuracy of 1 × 10 –4 for the root-mean-square force error in the real and K -space, resulting in an Ewald parameter of approximately 0.3 × 10 –10 m for all simulations.…”