Ion-Conducting Nanocrystals Theory, Methods, and Applications

The aim of this chapter is to review the current state of knowledge in ionic materials with crystallite dimensions less than 100 nm, systems which sometimes are referred to as nanoionics. The chapter will detail the preparation, characterization and the important applications of these materials, especially in sensors, solid-state batteries, and fuel cells. Particular focus will be placed on ionic transport in these materials, as this is a topic of considerable contemporary interest, and where conflicting reports exist of enhanced diffusion in nanocrystals. 

Nanomaterials are systems that contain particles with one dimension in the nanometer regime. The past decade has witnessed a growing intense interest from biologists, chemists, physicists, and engineers in the application of these materials -the so-called nanotechnology , which is sometimes referred to as the next industrial revolution [1]. The reasons for such interest are the unusual properties and potential technological applications that are exhibited by these materials when compared to their bulk counterparts [2-10]. In this chapter, attention will be focused onrather simple ionic solids, where the interatomic attractions are predominantly coulombic forces, and the dimensions are predominantly 100 nm. Such systems have been termed nanoionics [11,12]. 

There are three dominant reasons for the study of these particular systems  

The key property of these systems on which attention will be focused is the transport of ions. This fundamental property underlies many of the important processes and applications associated with ionic solids, and is still not fully understood when the solids are in nanocrystalline form. 

The origins of these unusual properties of nanomaterials are twofold  

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