Impact of annealing on physicochemical features of silver silica ceramic nanocomposite
| Reference | Presenter | Authors (Institution) | Abstract |
|---|---|---|---|
| 17-052 | Mateusz Dulski | Dulski, M.(University of Silesia); Peszke, J.(University of Silesia); Nowak, A.(University of Silesia); Zubko, M.(University of Silesia); Wojtyniak, M.(University of Silesia); Wlodarczyk, J.(University of Silesia); Dudek, K.(Institute of Ceramics and Building Materials); Podwórny, J.(Institute of Ceramics and Building Materials); | The metal ions in nano-sized form arouse great curiosity from many years. However, their application has certain limitations due to their potentially easy leaching and aggregating in the environment. This process can be stopped by a combination of metallic nanoparticles in an inorganic silica matrix. Other problems linked to the Ag/SiO2 are aging, the degree of oxidation or particle agglomeration changing at various temperature condition. Hence, determination of such parameters may help in finding the most optimal conditions at which porous systems will be the most stable, and the same interesting for the economic application. A new approach to the development of fabrication of the most stable silver nanoparticles embedded into silica carrier with an average size of 8.5 nm and different state of oxidation Ag0, or Ag+ has been applied. External metallic modifier implied appearance of non-stoichiometric silica moieties as well as structural disorder within silica framework. Annealing process has provided structural modification as well as a change in morphology, particle size, chemical composition and oxidation. Here, the silver concentration has been estimated as gradually decreasing with an increase of silica compaction, gradually particle agglomeration up 170 nm, formation of silver clusters as well as oxidizing of metallic silver to Ag+ and Ag2+. Above 1473 K, the composite undergoes transformation to a highly crystalline system with cubic silver and crystalline cristobalite and tridymite silica. This thermal condition strongly modified silica network carrier into the stoichiometric arrangement as well as provided partially reduction of silver to Ag+ with modification of its chemical bonding to silica framework and particle diameter to 12.4 nm. These studies have provided for the first time the development of “pseudo” phase diagram of structural changes of Ag/SiO2 nanosystem as well as a model of silver degradation and silica structure transformation.
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