Russian Journal of Applied Chemistry, 2013, Vol. 86, No. 8, pp. 1161−1167.
Pleiades Publishing, Ltd., 2013.
Original Russian Text © R.G. Romanova, E.Yu. Sitnikova, A.F. Dresvyannikov, 2013, published in Zhurnal Prikladnoi Khimii, 2013, Vol. 86, No. 8, pp. 1183−1190.
AND INDUSTRIAL INORGANIC CHEMISTRY
The Composition and Thermal Behavior of Nanodispersed Silica
Synthesized by Micellar Technology
R. G. Romanova, E. Yu. Sitnikova, and A. F. Dresvyannikov
Kazan National Research Technological University, Kazan, Russia
Received May 27, 2013
Abstract—Morphology, particle size, and thermal behavior of silicic acid synthesized as gel by micellar tech-
nology were determined. It was found that the micellar synthesis using a smaller-molecule solvent, organic acid
with shorter hydrocarbon (hydrophobic) part, as surfactant and silicate with smaller-radius cation yields silica
gel with smaller particle size and, as consequence, increases silica dispersity. The differential thermal analysis of
the synthesized silica gel showed that for samples with lesser particle size the phase transition temperatures are
decreased by about 30–100°C.
Presently, ceramics based on cordierite structures
of the composition MgO–Al
is one of the
most promising materials for the manufacture of
insulating semiconductor structures and piezoelectric,
magnetic, metal-ceramic, and other products [1–7]. The
above ceramics has considerable dielectric constant,
mechanical strength, and thermal resistance, which
mainly result from the phase and chemical composition
and macro-and microstructural parameters [8–11].
Phase homogeneity, chemical purity, and mechanical
strength of cordierite ceramics primarily depend on the
characteristics of the precursors (chemical composition,
morphology, and size of primary particles) used in their
synthesis and on the synthesis conditions [8–10]. The
traditional method of producing cordierite ceramics
is direct high-temperature solid-phase synthesis from
the oxides, natural alumina, or aluminosilicates (talc,
ﬁ re-clay, artiﬁ cial technical alumina, and electrofused
corundum). The disadvantage of this method is
incomplete interaction between the initial components
of the reaction mixture, which results in the presence
of unreacted initial phases in calcinations products.
In addition, the kinetics of these processes limited by
mutual diffusion of atoms and ions largely depends on
the fractional composition of starting materials. Owing
to composition heterogeneity, the monitored parameters
of samples taken from the same batch differ considerably
(by more than 30% in the ceramic materials synthesized).
Therefore, development of the technology for
preparing highly dispersed precursors, silicon,
aluminum, and magnesium oxides in particular, which
ensures the most complete phase transition to cordierite
at lower temperatures, is the urgent problem. Recently,
the sol-gel synthesis of nanodispersed materials
using simple procedures and accessible reagents and
equipment [2–6], ensuring obtaining the target products
with narrow particle size distribution as compared with
conventional method is widely used.
We studied silica samples obtained in nanoreactors,
which represent a mesophase of the surface-active agent
(SAA) with diphilic structure dissolved in an organic
solvent [12, 13].
We studied silica samples synthesized in accordance