Light element group 13–14 clathrate phases

There has been a renewed interest in clathrate compounds composed of light elements as promising thermoelectric materials due to their potential for chemical tuning. Clathrate structures are ideal frameworks for investigating the phonon glass electron crystal (PGEC) model for efficient band engineering. In this model, the guest atom provides for phonon scattering (phonon glass) to reduce thermal conductivity while tuning the chemical composition of the framework allows for control over electronic transport (electron crystal). This chapter provides an overview of the synthesis, structure, and properties of light element group 13-Si compounds with the clathrate structure. The primary focus will be on alkali and alkaline earth metal containing clathrates, A8ExSi46-x (A = Sr, Ba, Eu, Na, K; E = B, Al, Ga). Additionally, hydrogen capacity in Si clathrate structures will be presented. By reviewing the current status of the field, we will demonstrate the potential of these materials for electronic and thermoelectric applications and new avenues for research.