1070-4272/05/7807-1035+2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 7, 2005, pp. 1035!1037. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 7,
2005, pp. 1057!1059.
Original Russian Text Copyright + 2005 by Basiev, Batyrev, Voronov, Konyushkin, Kuznetsov, Osiko, Samartsev, Samoilova, Fedorov.
AND INDUSTRIAL INORGANIC CHEMISTRY
Hydration of Strontium Chloride and Rare-Earth
T. T. Basiev, N. I. Batyrev, V. V. Voronov, V. A. Konyushkin, S. V. Kuznetsov,
V. V. Osiko, A. M. Samartsev, E. B. Samoilova, and P. P. Fedorov
Scientific Center of Laser Materials and Technologies, Institute of General Physics,
Russian Academy of Sciences, Moscow, Russia
Lomonosov Moscow State Academy of Fine Chemical Technology, Moscow, Russia
Received November 15, 2004
Abstract-Hydration and dehydration (on calcination) of SrCl
, YOCl, and HoOCl powders were studied.
Single-crystal chloride materials are of interest for
photonics owing to their transparence in the IR range
and a [soft] photon spectrum. The main problem in
both growing the crystals and working with them is
their hydration. In particular, chlorides of rare-earth
elements are very hygroscopic; hydrated rare-earth
chlorides are readily hydrolyzed on heating .
This substantially complicates the use of such materi-
als, though the spectroscopic characteristics, e.g., of
single crystals are highly promising .
Among matrices resistant to moisture are PbCl
In this study we examined the hydration of SrCl
powders and also of oxychlorides of rare-earth ele-
ments. Strontium chloride crystallizing in a cubic
lattice of the fluorite type has a high isomorphous
capacity with respect to chlorides of rare-earth ele-
ments . Properties of SrCl
single crystals and of
solid solutions have been studied re-
peatedly . Oxychlorides of rare-earth elements
are more resistant to moisture than the chlorides .
Therefore they could be a convenient form for intro-
We used ultrapure 734 grade SrCO
pure grade ammonium chloride NH
Cl, and chemical-
ly pure grade hydrates of rare-earth elements RCl
O as starting substances. The initial chemicals
were characterized by X-ray diffraction. The X-ray
phase analysis was carried out on a DRON-2 diffrac-
radiation, focusing monochromator
from pyrolytic graphite). We recorded variations in
sample weights on an Acculab V-200 electron balance.
The humidity was measured with a psychrometer.
The hydration was carried out at 19+2oC and the rela-
tive humidity of 38+5%.
We prepared strontium chloride by the reaction
Cl = SrCl
8 + 2NH
We used a fourfold excess of NH
Cl. The reaction
was carried out in an alundum crucible at 1503350oC
for 6 h. The yield of SrCl
was 99%. The resulting
had a cubic fluorite-type lattice with a =
6.977 A, which agrees with the published data (PDF
card no. 38-0496). On exposure to air, the sample
weight continuously increased; the process gradually
decelerated with time (Fig. 1). The increase in the
substance weight in the first hour was 7%. The in-
crease in the sample weight was accompanied by
changes in its X-ray pattern. Along with the SrCl
lines, an additional set of reflections appeared, and
their intensities rapidly increased, whereas the lines of
weakened (Fig. 2). Analysis of the pattern using
the PDF database revealed mixture of mono-, di-, and
hexahydrates of SrCl
. The final hydration product
O. On calcination of strontium chlor-
ide hexahydrate at 350oC for 2 h, the weight loss cor-
responded to complete dehydration. The subsequent
Fig. 1. Kinetics of SrCl
hydration. (,m) Change in the
weight of the sample and (t) time.