Understanding the dynamics of electronic excitations at interfaces of polycrystalline oxides is important for photo-catalysis and for improving the performance of gas sensors as well as oxide fuel cells. We compare the electronic structure, spectroscopic properties and dynamics of electron and hole polarons and excitons in MgO, monoclinic and other phases of ZrO2 and HfO2, and at surfaces and grain boundaries of these materials. In cubic MgO, the high symmetry and coordination of Mg and O sites play the crucial role in localizing electrons, holes and excitons and their dynamics follows the terrace-step-kink model. The different character of chemical bonding and small asymmetry in the lattice structure of m-ZrO2 and m-HfO2 impose a quasi-2D hole localization and conductivity in these materials. In nano-crystals of m-ZrO2, holes move to surfaces and are strongly bound in 1D lines of two-coordinated O ions with high barriers for hopping motion.

Dynamics of polarons and excitons in polycrystalline oxides

244th National Meeting (2012)

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