ISSN 1070-4272. Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 3, pp. 345!350. + Pleiades Publishing, Inc., 2006.
Original Russian Text + A.G. Belous, O.Z. Yanchevskii, A.V. Kramarenko, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 3,
AND INDUSTRIAL INORGANIC CHEMISTRY
Synthesis of Nanosize Particles of Cobalt
and Nickel Oxides from Solutions
A. G. Belous, O. Z. Yanchevskii, and A. V. Kramarenko
Institute of General and Inorganic Chemistry, National Academy of Sciences of Ukraine, Kiev, Ukraine
Received July 4, 2005; in final form, January 2006
Abstract-Rounded nanosize particles of Co
and NiO were prepared by precipitation with ammonium
carbonate from cobalt and nickel nitrate solutions. Cobalt and nickel oxides and their precursors were char-
acterized by thermal and X-ray phase analyses, electron microscopy, and IR spectroscopy.
Nickel and cobalt oxides and materials based on
these compounds possess valuable dielectric, semi-
conducting, magnetic, and catalytic properties. They
are used as electrode materials [1, 2], heterogeneous
catalysts [3, 4], and materials for active units of gas
sensors [5, 6]. Films of cobalt and nickel oxides can
find application in electrochromic devices .
High-performance ultrahigh-frequency insulators are
being developed on the basis of complex oxides of
cobalt and nickel .
The properties of bulk and film materials largely
depend on the morphology and size of particles.
Extensive studies of nanosize materials in the last
decade have shown that diminishing the particle size
to the nanolevel leads to a dramatic increase in the
activity of powders, which makes it possible to obtain
high-quality materials on their basis.
Nanosize cobalt and nickel oxides are commonly
produced by spraying pyrolysis , organometal-
lic copolymerization , sol3gel process ,
hydrothermal synthesis , solid-state reactions ,
precipitation in microemulsions , and precipi-
tation with urea [23, 24], carbonates of alkali metals
[25, 26], and ammonia . However, most of these
methods require special equipment or expensive
chemicals. Therefore, development of a comparatively
simple method for synthesis of nanosize cobalt and
nickel oxides, in which the powders obtained would
not be contaminated with reaction products, is a
The aim of this study was to develop a simple and
environmentally safe method for synthesis of nanosize
cobalt and nickel oxides and to examine their proper-
The synthesis was performed by precipitation from
solutions. Chemically pure grade cobalt and nickel
nitrates served as starting reagents, and ammonium
carbonate of the same grade, as a precipitating agent.
Cobalt and nickel carbonates were precipitated both at
fixed pH values in the range from 6.2 to 7.8 and with
gradual addition of the precipitant to a prescribed pH.
At pH values exceeding 8, the precipitates started to
appreciably dissolve because of the formation of
soluble complexes [Co(NH
The precipitates obtained were transferred onto a
porous glass filter and the filtration coefficient K
) was determined by the Darcy formula 
where Q is the volume (cm
) of a filtrate that passed
through a precipitate layer of thickness L (cm) and
surface area S (cm
) at a rarefaction H (cm of water
column) in a time t (s).
To improve the reliability of data, the filtration co-
efficient was calculated for each batch of the precipi-
tate as arithmetic mean of the results of three measure-
ments. The carbonate precipitate was washed to re-
ions with double-distilled water;
the precipitate was twice resuspended, with inter-
mediate washing with the same amount of water. After
the second resuspending, cobalt and nickel carbonates
were subjected to final washing with distilled water
taken in an amount of 20 ml per gram of the precipi-