Vasylkiv O. Physical-chemical principles of engineering of oxide nanosize powder systems as a basis for advanced ceramic production

The thesis is devoted to: (1) the solving of actual scientific and technological problem - establishing of physical-chemical principles of the controlled processes of synthesis of nanodispersed multicomponent oxide powder systems; (2) studying of the peculiarities of synthesis processes of nanosize multicomponent powders; (3) development of the methods and methodologies of engineering of multicomponent nanoreactors from unstable precursors; (4) ascertainment of mechanisms of agglomeration during chemical synthesis of the nanopowders as well as during thermally-activated processes of their synthesis, calcination, homogenisation, and preserving of their nanostructure during colloidal formation and sintering. The new approach of planning of the synthesis of nanosize oxide powders was addressed and realized. This approach allows preventing of the uncontrolled agglomeration which is the main problem of all traditional nano-synthesis processes. It allows engineering of the powders consisting of 30-40 nm nano-aggregates with homogeneous composition and uniform morphology. The concept of in situ engineering of micro-/nanoreactors was suggested. The thermo-activated processes of nucleation-growth of new phases and compositions could be realized within the volume of each single nanoreactor. Nanoreactors are aggregates/agglomerates of complex intermediate metastable products of synthesis, and/or aggregates of complex oxides in the case of their impregnation with other components. It allows localization of the solid and/or liquid phase reactions within the volume of a single nanoreactor, which provides the inherency of the final structure of the nanosize product. Introduction of mechanical and sub-micromechanical action into the chemical processing i.e., sonochemistry, nanoexplosive calcination, expands the possibilities of selected chemical engineering method. The advances of the nanoexplosive calcination/deagglomeration technique are demonstrated as well.