Talk given by

Dr. Vladimir Šepelàk

Institute of Nanotechnology

Karlsruhe Institute of Technology

Abstract: Technological and scientific challenges coupled with environmental considerations have prompted a search for simple and energy-efficient syntheses and processing routes of nanomaterials. This tutorial lecture provides an overview of recent research efforts in non-conventional mechanochemical syntheses (mechanosyntheses) of different families of complex nanostructured oxides (stannates, silicates, ferrites, aluminates, germanates, gallates) with a variety of structure types (spinel, orthorhombic, olivine, perovskite, garnet).

Due to the ability of spectroscopic methods (NMR, Mössbauer spectroscopy, XPS, Raman spectroscopy) to provide structural information on a local atomic scale, valuable insights into (i) the nonequilibrium cation distribution, (ii) the canted spin arrangement, (iii) changes in the geometry of constitutive polyhedra, and (iv) the mechanically triggered formation of defective cation centers with the unsaturated oxygen coordination, in oxides are obtained. It is revealed that functional properties and stability of nanooxides prepared by mechanochemical routes are determined to a large extent by a far-from-equilibrium structural state of their interfacial/near-surface regions.

The lecture demonstrates that the event of mechanically induced chemical reactions provides novel opportunities for the non-thermal manipulation of nanomaterials and for the tailoring of their properties.