Inhomogeneity and anisotropy of chemical bonding and thermoelectric properties of materials

Abstract

While the phenomenon of thermoelectricity is well understood from the physical point of view, the chemical aspects of thermoelectric properties are still under consideration. This lack of knowledge slows down the search and the development of new materials with good thermoelectric perspective. In order to overcome this shortfall, analysis of chemical bonding in thermoelectric and related materials was realized by quantum chemical techniques in position space. The present study shows that atomic interactions play a key role in the chemical and structural organization of thermoelectric materials as bonding features are the substantial reason for the crystallographic complexity and the physical behavior. Atomic interactions (bonding) form the basis for the total electron balance in the material regulating electron concentration and transport (electron engineering) as well as the heat transport in the material (phonon engineering). The spatial distribution of regions with different types of chemical bonding – bonding inhomogeneity and anisotropy - influences thermal and electronic transport more than crystallographic only features.