Small Polarons in Transition Metal Oxides

The formation of polarons is a pervasive phenomenon in transition metal oxide compounds, with a strong impact on the physical properties and functionalities of the hosting materials. In its original formulation the polaron problem considers a single charge carrier in a polar crystal interacting with its surrounding lattice. Depending on the spatial extension of the polaron quasiparticle, originating from the coupling between the excess charge and the phonon field, one speaks of small or large polarons. This chapter discusses the modeling of small polarons in real materials, with a particular focus on the archetypal polaron material TiO2. After an introductory part, surveying the fundamental theoretical and experimental aspects of the physics of polarons, the chapter examines how to model small polarons using first principles schemes in order to predict, understand and interpret a variety of polaron properties in bulk phases and surfaces. Following the spirit of this handbook, different types of computational procedures and prescriptions are presented with specific instructions on the setup required to model polaron effects.Comment: 36 pages, 12 figure

ELECTRICAL CONDUCTION AND CORROSION PROCESSES IN FAST LITHIUM ION CONDUCTING GLASSES

Photograph of a large stone, Yu Yuan Garden, Shanghai, ChinaTaihu stone at Yu Yuan Garden, Shanghai, China

LOW TEMPERATURE REOXIDATION KINETICS IN SrTiO3

La cinétique d'oxydation du SrTiO3-x a été étudiée à température basse par l'entremise de technique photoéléctrochimique de profile de lacune d'oxygène. Nous avons observé la cinétique d'oxydation des surface endommagées est contrôlée par l'échange en surface alors que pour les surface décapées, la cinétique est contrôlée par une diffusion en volume, caractérisée par une énergie d'activation de 1.16 eV, jusqu'à la température ambiante.The low temperature oxidation kinetics of SrTiO3-x were investigated by examining oxygen vacancy profiles photoelectrochemically. Surface exchange limited kinetics controlled reoxidation at damaged surfaces while bulk diffusion, characterized by an activation energy of 1.16 eV, controlled down to room temperature at etched surfaces