Layered Rare Earth Hydroxides: Structural Aspects and Photoluminescence Properties

Layered rare earth hydroxides (LREHs), a special class of layered solids featuring cationic host layers of rare earth (RE) hydroxides, have become recognized as novel multifunctional materials in which the intercalation reactivity and host–guest interaction are coupled with the appealing physicochemical properties of RE elements. This chapter presents a background survey and an up-to-date overview on the development of LREH materials in terms of their synthesis, structural characterization, and photoluminescence properties. We first summarize the synthetic strategies to produce LREHs in various forms. In the following section, the basic structural features of LREH compounds are illustrated for typical anionic forms, and we highlight the critical importance of this knowledge in interpreting their fundamental properties and functionality hunting. Then, the photoluminescence properties of LREH compounds are discussed. Various phosphors with tunable or enhanced performance, including forms of oriented films, exfoliated nanosheet crystallites, and hybrid nanocomposites, are designed based on the structural features of LREH compounds. We describe the major contributions to this topic from studies conducted before 2015.