Synthesis of the Ferroic Nanopowders

The strategy of top down is considered traditional for powders fabrication. Nanoparticles are the product of milling of large pieces of any material. The grinding process may also be accompanied by chemical and phase transformations. Theoretically, any substance can be crushed or converted to a vapor state and then condensed. However the problems of impurities, control of particle size distribution and the properties of agglomerates still remain open. 

Refining of the particle size can be achieved by etching of bulk sample. For example, the nanosize zirconia powder doped with yttrium has been prepared by etching of yttrium containing polycrystalline BaZrOs or NaaZrOs [15]. Preliminary sintered ceramics of BaZrOs or Na2Zr03 doped with yttrium was subjected to hydrothermal treatment to eliminate the undesirable ions of Ba + or Na+ in nitric acid solution or supercritical water. The etching precipitate represents yttrium-stabilized zirconia nanopowder with particle size of 3-15 nm. 

Methods for the synthesis of nanoparticles can be grouped into four categories chemical, physical, biological and combined. 

The physical process alters the physical properties of particles such as size, shape, and the phases of matter. Mechanical grinding and vapor condensation of matter in the form of nanoparticles are examples of physical methods of synthesis. 

Chemical synthesis alters the chemical composition. A major part of chemical synthesis processes are related to the inorganic substances, although recently 

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