Control of nanoparticle agglomeration through variation of the time-temperature profile in chemical vapor synthesis
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The influence of the time-temperature history on the characteristics of nanoparticles such as size, degree of agglomeration, or crystallinity is investigated for chemical vapor synthesis (CVS). A simple reaction-coagulation-sintering model is used to describe the CVS process, and the results of the model are compared to experimental data. Nanocrystalline titania is used as model material. Titania nanoparticles are generated from titanium-tetraisopropoxide (TTIP) in a hot-wall reactor. Pure anatase particles and mixtures of anatase, rutile (up to 11 vol.%), and brookite (up to 29 vol.%) with primary particle sizes from 1.7 nm to 10.5 nm and agglomerate particle sizes from 24.3 nm to 55.6 nm are formed depending on the particle time-temperature history. An inductively heated furnace with variable inductor geometry is used as a novel system to control the time-temperature profile in the reactor externally covering a large wall temperature range from 873 K to 2023 K. An appropriate choice of inductor geometry, i.e. time-temperature profile, can significantly reduce the degree of agglomeration. Other particle characteristics such as crystallinity are also substantially influenced by the time-temperature profile.
KeywordsCVS CVD Gas-phase synthesis Agglomeration TiO2 Modeling
This work was granted by the German Research Foundation (DFG) through the Collaborative Research Center SFB 445. We would like to thank Dr. Marina Spasova (Experimental Physics Department University Duisburg-Essen, Germany) and Dr. Ralf Theissmann (Institute for Nanostructures and Technology, University Duisburg-Essen, Germany) for the TEM imaging.
Compliance of ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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