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World Journal of Engineering
PLASMA-ASSISTED SYNTHESIS AND MODIFICATION OF COMPOSITE
NANOPARTICLES IN LIQUIDS
Nikolai Tarasenko, Andrei Butsen, Alena Nevar, Mikhail Nedelko, Mehdi Mardanian
Institute of Physics National Academy of Sciences of Belarus, Minsk, Belarus
generated by pulsed Nd:YAG lasers, operating at
1064 nm and 532 nm, each with 50 mJ pulse in a 5mm beam were used [2].
A pulsed discharge was generated between two
electrodes being immersed in liquid (Fig.2). An
optimum distance between the electrodes was kept
constant at approximately 0.3 mm to maintain a
stable discharge. The discharge was initiated by
applying a high-frequency voltage of 3.5 kV. The
power supply provided several different types of
discharges. Both direct current (dc) and alternating
current (ac) arc and spark discharges were
generated with repetition rates of 100 and 50 Hz
respectively. The peak current of the arc discharge
was 9 A with a pulse duration of 4 ms. The peak
current of the pulsed spark discharge was 60 A
with a pulse duration of 30 μs.
The synthesized products were characterized by
UV-Visible optical absorption spectroscopy,
transmission electron microscopy (TEM) and X-ray
diffraction analysis (XRD) for their size,
morphology, crystalline structure and composition.
Introduction
Last decade non-equilibrium plasmas generated by
pulsed laser ablation and electrical discharges in
liquids have attracted much attention for various
technological applications including fabrication of
advanced materials of different compositions [1, 2].
Preparation of nanosized particles with the welldefined morphology, structure and chemical
composition are crucial for achieving their unique
properties.
Laser ablation and electrical discharge in liquids
provide simple methods for the synthesis of
nanostructures with different stoichiometry, as a
function of material composition and solution
nature; narrow and controlled particle size
distributions. In the frame of these techniques one
can
combine
particle
synthesis
with
functionalization, encapsulation and stabilization of
products.
In the present paper experimental conditions
favoring the fabrication of particles of complex
compounds, for example nanoparticles of
chalcopyrite and chalcogenides, doped zinc oxides
as well as nanoparticle-polymer composites were
determined. Composite nanoparticles have attracted
intensive interests because of their unique
electronic, optical and catalytic properties, different
from those of their constituents. The composite
nanoparticles have the advantage of tuning and
tailoring their physical properties by designing the
chemical compositions.
Results and discussion
Both the developed techniques have been shown to
be suitable for a preparation of particles of various
compositions and morphologies with sizes in the
nanometric range. Plasmas in liquids can provide
extremely rapid chemical reactions due to a
presence of activated species and radicals under
high pressure. For example, various oxides
including ZnO:Ag, Gd2O3:Tb3+ were synthesized
via laser ablation in aqueous solutions.
It was rather unexpected that the stoichiometric
nanoparticles were formed under laser ablation of
chalcopyrite mineral (CuFeS2) in water. The
relative contents of Fe, Cu, and S atomic
components in the formed particles, determined
from the EDX spectrum, corresponded to the
stoichiometric ratio for the CuFeS2 phase. As it
followed from the diffraction pattern, the
Experimental
Laser ablation plasma (Fig.1) was generated by
focusing of radiation of a Nd:YAG laser (LOTIS
TII, model LS2134), operating at 1064 nm (energy
80 mJ/pulse, repetition rate 10 Hz, pulse duration
10 ns), on the surface of the solid target placed in
the cell filled with liquid. In double pulse ablation
experiments a combination of two laser beams
1101
World Journal of Engineering
synthesized powder consisted of tetragonal
chalcopyrite CuFeS2 (diffraction peaks at 2θ:
29.58, 48.78, 49.18, 57.98 and 58.78). Note that
there were few small peaks from the CuFe2S3 and
Cu2Fe4S7 phases near the diffraction peaks of
CuFeS2. Thus, the formation of metastable copperand iron-containing compounds is not excluded.
However, oxide phases were not observed. The
atomic force micrographs of the chalcopyrite
particles deposited on a mica substrate showed
agglomerates of nanoparticles, which were most
likely formed during deposition. The initial
particles were of approximately the same size (50 100 nm).
appropriate combinations of pairs of metallic and
graphite electrodes submerged into the appropriate
solution (ethanol, CuCl2 aqueous solution). The
synthesis rate varied in range of 2 – 40 mg min-1
depending on a peak current and pulse duration of
discharge as well as a polarity of metal and
graphite electrodes.
Fig.3 TEM image of copper particles synthesized
by spark discharge in CuCl2 aqueous solution
Another way to synthesize composite nanoparticles
is plasma processing of micropowders via electrical
discharge in liquid. Formation of carbide phases
was observed after plasma treatment tungsten
powders. It was also demonstrated that processing
of suspended powder mixtures by electrical
discharge in liquid can be employed to initiate
reactions between powder components. For
instance, plasma treatment of copper, indium and
selenium powders first mechanically pre-mixed in
the stoichiometrical proportions resulted in the
formation of CuInSe2 compound. Ternary
semiconductor
compounds
like
copper
chalcogenides are of particular interest as the most
perspective materials for use in photogalvanic
devices.
Fig.1 Schematic of laser ablation experiment,
power
supply
References
Fig.2 Schematic of electrical discharge experiment:
1 – electrodes, 2 – conoidal vessel, 3-plasma, 4powder.
1.Graham W.G. and Stalder K.R. Plasmas in
liquids and some of their applications in
nanoscience. Phys. D: Appl. Phys., 44 (2011)
174037 - 17445.
2. Tarasenko N.V., Butsen A.V. Laser synthesis
and modification of composite nanoparticles in
liquids, Quantum Electronics, 40 (2010) 986 -1003.
Promising capabilities of the electrical discharge
technique for synthesis of tungsten and titanium
carbides as well as carbon-encapsulated copper
nanoparticles (Fig.3) were demonstrated using the
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