Preparation and properties of polycrystalline aggregates of simple and hybrid alkali halides – An overview

Alkali halides crystals occur in either NaCl structure or CsCl structure and the crystalline alkali halides are important both purely scientific and technological. The importance and applications in several optical, optoelectronic, and electronic devices led to the preparation and characterization of polycrystalline aggregates (with reduced crystallite sizes at or below micro level) of several pure and hybrid (mixed and/or doped) alkali halides in the recent decades. Polycrystalline aggregates of alkali halides can be cut into any shape and polished for their utility in device applications. There are several reports available in the past about two decades on the polycrystalline aggregates of simple and hybrid alkali halides. Presented herewith is an overview of various studies made on the preparation and properties of polycrystalline aggregates of simple and hybrid alkali halides (both single-phased and multi-phased) focusing the results reported by the present author and his co-workers. The reported results have indicated that the optical (particularly absorption and photoluminescence) and electrical (particularly dielectric) properties can be tuned significantly by reducing the crystallite sizes of the polycrystalline aggregates of alkali halides.