Download Control of size of nano / micro particles synthesized by atmospheric

Control of size of nano / micro particles synthesized by atmospheric pressure
RF discharge
M.V. Mishin, K.Y. Zamotin, A.S. Kondrateva, V.S. Protopopova.
Investigation of various nano-objects formation is important basement of
development of micro and nano-electronics and other important technologies.
Nanoparticles formed from different materials are already used in modern
techniques to tailor properties on composite materials, ceramics, catalyzing agents
etc. Low temperature plasma created in reactive gas ambient by high frequency
electric discharge is successfully used to activate chemical vapor deposition
processes. Atmospheric pressure discharge has a number of advantages: simplicity
of technical implementation, high reactive substance concentration giving
significant reaction rate, low heat of a substrate due to low temperature plasma
discharge formation [1].
In this work the peculiarities of silicon dioxide micro and nano particle
formation in low temperature atmospheric pressure discharge was investigated.
Process was initiated in 13.56 MHz capacitive RF helium plasma. RF power was
15 W. Tetraethoxysilane (TEOS) was used as a source of silicon dioxide. The
dependence of particle size distribution on discharge parameters was studied.
Particles size in the range 0.2 – 3 μm were measured in-situ by optical technique.
Distribution of electric potential in reactor was studied by Langmuir probe and
additional homebuilt probe [2].
Strong inhomogenity of electric potential distribution along reactor axes was
found. Such a distribution was caused by injection of ions from discharge area.
Numerical simulations of formed particle motion have indicated notable changes in
the way particles shifts through reactor especially in non uniform electric field
area. Some of particles can grow in size and coagulate. Possibility to grow particles
of predefined size by control of electric potential in reactor zone was
experimentally verified. Experimental data correlate well to simulated results.
1. S. E. Alexandrov and M. L. Hitchman, Chem. Vap. Deposition. 11(11-12), 457 (2005).
2. M. V. Mishin, V. S. Protopopova, A. A. Uvarov, S. E. Alexandrov, AIP Advances. 4, 107130
(2014).