LaGaO3 doped with Sr2+ on the A-site and Mg2+ on the B-site (LSGM) has been suggested as an alternative electrolyte material for a range of devices which can operate in the intermediate temperature range of 600-800°C. These include solid oxide fuel cells (SOFCs), solid oxide electrolysis cells (SOECs) and solid oxide reversible cells (SORCs). While bulk conductivity has been extensively studied for LSGM the interfaces present, due to multi-crystallinity, and their effect on oxide ion conductivity in LSGM have been largely ignored despite their importance in the oxide ion conduction of materials such as fluorite. Here we present the derivation of a highly accurate dipole polarizable ion model (DIPPIM) force field for doped-LaGaO3 where the dopants are Sr2+ on the A-site and Mg2+ on the B-site. In the DIPPIM polarization effects resulting from induced dipoles on ions in the system are taken into account, which is of great importance due to the polarizable nature of the O2- ions in doped-LaGaO3. The force field is fitted to force, stress and dipole data obtained from DFT calculations, allowing non-equilibrium details on the potential energy surface to be accounted for, which is not possible when fitting to experimental data. Consequently the DIPPIM force field is highly accurate. The DIPPIM force field has been used to perform a molecular dynamics study of the effects of interfaces (surfaces and grain boundaries) on oxygen diffusion in LSGM along with diffusion in bulk LSGM at range of dopant concentrations and temperatures.

Interatomic potential for a perovskite electrolyte derived from first principles

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.