Finding a path through a crystal. Theoretical modelling of ionic conductivity.

Sammanfattning: Ionic conductors have seen increased use over time. These are found in ion detectors, gas detectors and supercapacitors but finds special use in fuel cells and solar cells. Some ionic conductors are not only used as a conductor, but finds uses as insulators, ceramic blades or even as a diamond simulant. Most other works no ionic conductors concentrate on the general or macroscopic properties. Here the mechanism of the ionic conduction is studied in microscopic detail. A theoretical model has been chosen to simulate the conductivity in a crystal lattice using a quantum chemical software to calculate the energies. A few structures were chosen for study, CaF2 a known non-ionic conductor, LaF3 and ZrO2 both known ionic conductors. The model may not simulate the ionic conduction perfectly but initial results are promising as relatively good agreement between experimental results and simulations can be observed, especially in the simulation with zirconia. A clear difference was seen between a non-conductor and a conductor and between systems with and without defects. The ions most likely move one at a time. Doing studies on more detailed and modified paths as well as introducing dopants may yield further results.