Hydrothermal Nanotechnology: Putting the Last First

Abstract

Nanotechnology has been around us since 50 years and different scientific institutions and researchers have tried to define it uniquely. One such definition provided by the European Commission is “Nanotechnology is the study of the phenomena and fine tuning of materials at atomic, molecular and macromolecular scale, where properties differ significantly from those at the larger scale”. Nanoparticles can be synthesized by various methods, namely physical, chemical, and biological or combination of them. Hydrothermal technique is a popular method of obtaining nanomaterials which epitomizes the natural conditions existing under the earth’s crust and meets the global concern and awareness for the development of environment-friendly materials. It refers to any heterogeneous reaction in the presence of aqueous solvents under elevated pressure and temperature conditions to dissolve and recrystallize materials that are relatively insoluble under ordinary conditions. As there are a number of processing variables which can be controlled during hydrothermal synthesis, it can be hybridized with several other processes to obtain highly crystalline products with narrow size distribution, high purity, and low aggregation. In this chapter we build a notion of hydrothermal synthesis and how it can be hybridized with other techniques of material synthesis and summarize the report furnished by different researchers on these aspects. At last we provide a comprehensive study of Ba(Fe1/2Nb1/2)O3 prepared by solid-state reaction method, hydrothermal method and mechanochemical method.