Berlin 2012 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 39: Topical Session Theory meets Experiment IV - Batteries, Thermoelectrics and Thermal Barrier Coatings

MM 39.4: Vortrag

Mittwoch, 28. März 2012, 17:15–17:30, TC 006

Computational study of structures of yttria-stabilised zirconia/strontium titanate multilayers — •Wei Li Cheah and Mike Finnis — Imperial College London, UK

Growing interest in the field of functional oxide multilayered nano-heterostructures may be attributed to their unusual interfacial properties that are not yet fully understood. For instance, the nature of the unexpectedly high conductivity reported in a trilayer of 1-nm thick epitaxial yttria-stabilised zirconia (YSZ) film sandwiched between strontium titanate (STO) layers [1] still remains controversial. In an effort to investigate the source of conductivity in this system, we first establish an unexpected YSZ lattice within such heterosystem using a combination of techniques - a genetic algorithm in which the interatomic forces are described by classical pair potentials, and a pseudopotential-based DFT method as implemented in the plane-wave code CASTEP. We find this structure to be more stable than an anatase zirconia epitaxial lattice on STO which has been previously found as the most stable structure if yttrium dopants were not incorporated within the zirconia layer. Analysis of charge density of this new structure reveals not localised vacancies, but several small pockets of low charge densities for each expected vacancy. We examine the mobility of oxide ions in the heterosystem using classical molecular dynamics simulation and attempt to relate the results to experimental conductivity values.

[1] J. Garcia-Barriocanal et al., Science, vol. 321, no. 5889, pp. 676-680, 2008.