Radiation induced preparation of nanocrystalline oxides
Dr Václav Čuba
Czech Technical University (Prague)
Mardi 17/04/2012, 14:30
NIMBE Bât.546, p.21, CEA-Saclay
This talk will provide brief summary of activities of radiation chemistry research group at Czech Technical University in Prague.
Major part of the presentation will be aimed on the preparation of various inorganic (oxide) nanomaterials via irradiation of aqueous solutions containing precursors, i.e. soluble metal salts and radical scavengers by ionizing and non ionizing radiation.
Direct and indirect preparation of simple oxides, mixed oxides, garnets and spinels will be presented. Namely, results on radiation induced preparation of cuprous, nickel, zinc, yttrium and aluminium oxides will be presented, as well as zinc peroxide, yttrium / lutetium - aluminium garnets and cobalt(II)-aluminate. Doping of these compounds with low concentrations of foreign ions will be also discussed. Among mentioned compounds, only zinc oxide and zinc peroxide were prepared directly via irradiation at room temperature. For preparation of other crystalline compounds, additional heat treatment (at low temperature) of solid phase formed under irradiation is necessary.
With regards to radiation sources, preparation using accelerated electrons, high energy gamma radiation and UV radiation will be discussed, including possible differences in the process of synthesis under various conditions and mechanisms of solid phase formation in radiation field.
All used modifications of radiation method are rather convenient and simple, and yield (nano)powder materials with interesting features. Prepared materials generally have high chemical purity, high specific surface area and narrow distribution of particles size.
Generally, all types of radiation yield materials with comparable properties and structural characteristics, but currently available data suggest that accelerated electrons are more suitable for the preparation of compounds doped with foreign ions, while UV radiation is better for preparation of more intricate stoichiometric compounds such as synthetic garnets.