1070-4272/05/7801-0050C2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 1, 2005, pp. 50 !52. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 1,
2005, pp. 52!54.
Original Russian Text Copyright + 2005 by Egorova, Radishevskaya, Bykonya, Shul’pekov.
AND INDUSTRIAL INORGANIC CHEMISTRY
Reaction of Cobalt Phosphomolybdate with Alcoholic Solutions
of Tetraethoxysilane and Zirconium(IV) Oxychloride
L. A. Egorova, N. I. Radishevskaya, N. V. Bykonya, and A. M. Shul’pekov
Tomsk State University, Tomsk, Russia
Department of Structural Macrokinetics, Tomsk Scientific Center, Siberian Division,
Russian Academy of Sciences, Tomsk, Russia
Received November 4, 2004
Abstract-Alcoholic solution of tetraethoxysilane was studied IR-spectroscopically. The compositions with
various ratios of a binder and thermochromic substance were prepared, and their structure and thermal stability
were studied. Mixtures of cobalt phosphomolybdate with tetraethoxysilane alcoholic solutions show promise
for obtaining thermochromic compositions with the range of the working temperatures 3503400oC.
Phosphomolybdates of iron-like metals are materi-
als for obtaining thermochromic compositions used
for visual temperature monitoring of out-of-the-way
places of devices, furnaces, etc., working at high tem-
peratures. As a rule, thermochromic substances are
applied onto the monitored surface as the composi-
tions with various organic binders. However, the
organic component rapidly loses its performance
under the periodical impact of high temperatures.
The binders based on inorganic compounds are more
promising. In this work, we propose to use alcoholic
solutions of Group IV element compounds as binders.
Thermolysis of such compounds gives thermostable
oxides as a matrix in which the thermochromic com-
ponent is distributed.
In this work, we studied alcoholic solutions of
tetraethoxysilane (TES) and oxyzirconium chloride as
binders for obtaining thermochromic materials based
on cobalt phosphomolybdate.
Cobalt phosphomolybdate was prepared from
chloride solutions by the method described in . The
quantitative ratio of the initial components and the
solution pH (pH < 1) were strictly controlled, which
ensured formation of compounds with the Keggin
structure. The crystalline form was prepared by the
prolonged evaporation of the mother liquor. Cobalt
phosphomolybdate obtained is a yellow powder read-
ily soluble in water and ethanol. Phosphomolybdate
and its compositions were identified by chemical,
X-ray phase (a DRON-UM1 diffractometer, filtered
Co radiation), and thermal (a Q-1500 derivatograph,
MOM, Hungary) analyses and IR spectroscopy within
the 40003 400 cm
range (a Specord M-80 spectrom-
Fig. 1. IR spectra of (1) cobalt phosphomolybdate and its
compositions with alcoholic solutions of (2) tetraethoxy-
silane and (3) zirconium oxychloride. (T) Transmittance
and (n) wavenumber.
eter; samples were prepared as KBr pellets). Color
transitions were determined visually at heating of the
compositions in a furnace; the temperature was moni-
tored with a Chromel3Copel thermocouple. The al-
coholic solutions of tetraethoxysilane (20 vol % TES)
and zirconium(IV) oxychloride (0.4 M) were used as
binders . The contents of the components were
selected so that the solutions could be used for a long
time. The compositions were prepared by mixing of
the heteropoly compound (HPC) and the correspond-