Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 1, pp. 7−13.
Pleiades Publishing, Ltd., 2010.
Original Russian Text
S.A. Suvorov, V.N. Fishchev, N.V. Alekseeva, 2010, published in Zhurnal Prikladnoi Khimii, 2010, Vol. 83, No. 1, pp. 9−15.
INORGANIC SYNTHESIS AND INDUSTRIAL
The Effect Exerted by Composition and Temperature
on the Decomposition Stability
of Anosovite Solid Solutions
S. A. Suvorov, V. N. Fishchev, and N. V. Alekseeva
St. Petersburg State Technological University, St. Petersburg, Russia
Received July 7, 2008
Abstract—Chemical modification of potato carboxy starch in the sodium pyrosulfate–dimethyl sulfoxide system
was studied with the aim of preparing water-soluble highly substituted sulfo esters. The dependence of the degree
of sulfo group substitution on the reaction conditions was studied in detail. The optimal conditions ensuring
formation of water-soluble sulfo esters of carboxy starch with the maximal sulfur content were determined.
The carboxy starch sulfo ester samples synthesized were characterized by elemental analysis, IR and
spectroscopy, and high-performance exclusion chromatography.
Based on the energetic concept of the solid solution
theory, a calculation estimate was done for the positions of
the mutual solubility boundaries in the system aluminum
titanate-magnesium dititanate. It was shown that a regular
substitution of the crystal lattice sites for Mg
ions must result in a limited mutual solubility
of the above compounds. The decomposition stability of
the anosovite solid solutions over the whole range of the
compositions was studied experimentally, depending on
the temperature and time of the thermal exposure.
Aluminum titanate (Al
) has attracted considerable
attention to the development of thermally stable
compositional materials because of its unique properties:
sufﬁ ciently high melting temperature (1860°С), a low
temperature linear expansion coefﬁ cient (TLEC), which
is negative in a wide temperature range, and stability in
acid media and silicate melts [1, 2]. At the same time,
TLEC of aluminum titanate has marked anisotropy
along the crystallographic axes. Therefore, fabrication
of stable aluminum titanate articles in sintered state is
made difﬁ cult owing to the appearance of mechanical
stresses and microcracks in quenching. Upon prolonged
exploitation in the temperature range 900–1200°С
aluminum titanate decomposes onto starting oxides,
which leads to loss of strength by the articles owing to
the appearance of phases with high LTEC value . All
this also sets a limit for its application.
It is known that the additives forming the solid
solutions with aluminum titanate increase its stability.
Therefore, a study of the conditions of existence of the
solid solutions between aluminum titanate and magnesium
dititanate is of special importance [4, 5].
The above compounds belong to the MgO–Al
ternary system, wherein MgAl
anosovite solid solutions form two
series of the continuous solid solutions [6, 7].
The mineral anosovite, called after the name of
the outstanding metallurgist-scientist P.P. Amosov,
was found for the first time in a high-titanium slag
by K.Kh. Tagirov . The anosovite composition
corresponds to the formula Ti
The aluminum titanate crystal structure has been
determined in  virtually simultaneously with the
anosovite structure . The above compounds belong to
the rhombic crystal system isostructural to pseudobrookite
[12, 13], which contains four А
formula units in the
elementary cell. In the pseudobrookite structure, each
B ion is surrounded by oxygen ions in the octahedral
coordination. The A ions can be surrounded either by