Regensburg 2013 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 7: Computational Materials Modelling - Methods

MM 7.3: Talk

Monday, March 11, 2013, 12:15–12:30, H24

New Methods for Calculating the Free Energy of Charged Defects in Solid Electrolytes. — •Robert Horton, Andrew Haslam, Amparo Galindo, George Jackson, and Michael Finnis — Imperial College London, London, United Kingdom

Solid electrolytes are utilised in a myriad of technological applications ranging from fuel cells to gas sensors. It is the presence of charged defects in their lattice structure that is primarily responsible for their useful electrolytic behaviour [1] and, accordingly, a detailed understanding of the thermodynamic behaviour of these defects is highly desirable. Analytic models for describing the thermodynamic contribution of defects break down at concentrations of a few percent, due to the long-ranged nature of the Coulombic defect-defect interactions. We have developed and tested an alternative scheme, using Wang-Landau sampling [2], a temperature-independent Monte Carlo method, to statistically calculate the free energy of the system at the atomistic level. It is interesting to see that this calculated free energy can be fitted by traditional functional forms, such as regular-solution and Redlich-Kister, with which the thermodynamic properties of the system can be calculated.

[1] S. C. Singhal (2000). Science and Technology of Solid-Oxide Fuel Cells. MRS Bulletin, 25, pp 16-21 doi:10.1557/mrs2000.13

[2] F. Wang and D. P. Landau, (2001). Physical Review E. 64, 056101-1-16.