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2011-Sustainable Industrial Processing Summit
|Publisher:||Flogen Star OUTREACH|
|ISSN:||2291-1227 (Metals and Materials Processing in a Clean Environment Series)|
Microwave Assisted Synthesis of Nano-scaled Metal and Ceramic PowdersM. Willert-Porada. E. Fuchs, M. Singh, Z. PajkicUniversity of Bayreuth, Chair of Materials ProcessingProcesses for synthesis of nanoscaled powders have to insure control of purity and of morphology for such powders. Two different strategies can be applied: pre-synthesis surface energy control or post-synthesis surface energy control within a high energy synthesis process.The pre-synthesis surface energy control processes are based on templates used in colloids or emulsions as micro-reactors or on agents which form stable complexes with the precursors during powder synthesis. Examples of such processes are Colloidal, Emulsion, Chemical Solution Deposition (CSD) or Polyol based powder syntheses. The potential of process kinetic enhancement is very limited upon such process conditions.Opposite to this, kinetic influence is high upon high energy synthesis processes. In particular, enhancement of reactions is possible upon plasma chemical vapour deposition, PE-CVD. Powder synthesis processes at ambient pressure are of particular importance, because of many existing flame powder syntheses. Upon atmospheric pressure microwave radiation offers the highest process stability for plasma generation.Therefore, in case of microwave plasma high energy synthesis processing conditions can be combined with Colloidal, CSD or Polyol reaction conditions because microwave fields enable plasma condition in gaseous as well as liquid fluids. Microwave assisted processes open up the way to combine surface energy controlled nanopowder synthesis with kinetic control of processes.The paper will present fundamentals of heat and charge transfer upon microwave assisted colloidal and polyol processing of Nano-powders as well as PE-CVD fundamentals. Synthesis of Oxides, like e.g., ZrO2 and nano-TiO2, Phosphates, like nano-LiFePO4, metals like Ni and Semi-conductors, like Silicon will be discussed.