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Russian Journal of Applied Chemistry, Vol. 75, No. 3, 2002, pp. 370 !374. Translated from Zhurnal Prikladnoi Khimii, Vol. 75, No. 3,
2002, pp. 383!387.
Original Russian Text Copyright + 2002 by Sladkov.
OF SYSTEMS AND PROCESSES
Density of Liquid Halogermanes
I. B. Sladkov
St. Petersburg State Technical University, St. Petersburg, Russia
Received June 26, 2001
Abstract-The density of liquid bromo- and iodogermanes was calculated by four independent methods at
temperatures between the melting and boiling points. The coefficients of a temperature series of density were
established and the accuracy of the results obtained was analyzed. The reliability of the obtained data was con-
firmed by variation of the molar volume of a liquid substance in the series of halogermanes and halosilanes.
Germanium compounds containing hydrogen and
chlorine atoms (chlorogermanes) are widely used for
preparing single-crystalline germanium and for manu-
facturing semiconductor devices. The procedures com-
monly involve reduction of chlorogermanes with
hydrogen. The germanium compounds with hydrogen
and bromine (bromogermanes) and those with hydro-
gen and iodine (iodogermanes) are reduced with hy-
drogen more readily than chlorogermanes. Therefore,
it may be appropriate to use them when the lower
process temperature is the decisive factor.
At the same time, bromo- and iodogermanes are
studied considerably less than chlorogermanes; pres-
ently, many of their physicochemical properties re-
main unknown. For example, data are lacking on the
temperature dependence of the density in the liquid
In this work we obtained, using approximate proce-
dures of the thermodynamic similarity principle, the
lacking data on the density of these compounds. The
reliability of the methods used was tested on related
compounds for which experimental data on the den-
sity were available.
To calculate the density of liquid bromo- and
iodogermanes, we used four independent procedures.
Procedure 1 is based on the law of respective states.
According to this law, thermodynamically similar
substances must have similar reduced volumes in the
liquid state at the same reduced temperature. Calcula-
tion of the density by procedure 1 involves a choice of
a few compounds that are thermodynamically similar
to the compounds under consideration, for which the
density in the liquid phase, critical temperature T
and critical volume V
are known from the literature.
The reduced volumes, V
, of these sub-
stances in the liquid state, as calculated for a given
reduced temperature T
, should be close.
Their average value can be accepted as the reduced
volume of the substances under consideration at a
given reduced temperature.
The thermodynamically similar substances should
be chosen so as to ensure close values of the com-
plexity factor of intermolecular interaction (y-factor)
, which is the determining criterion of thermo-
dynamic similarity of inorganic molecular com-
pounds. Therefore, we chose chloro- and bromoger-
, for which data on the density in the liquid
state are available from the literature . Tables 1 and
2 present, according to , the physicochemical prop-
erties necessary for the calculation. In Table 1 the
properties of the substances studied (nos. 7311) are
given along with those of the thermodynamically
similar compounds (nos. 136).
Evidently, the chosen reduced temperatures for cal-
culating the reduced volumes of the substances should
correspond to their liquid state. It is infeasible to
estimate the lower temperature boundary of the liquid
state without data on the melting point. However, the
melting point of iodogermanes is unknown. To deter-
mine it, we used a correlation between the melting
and boiling points for this class of substances (Fig. 1).
Fig. 1. Correlation between the melting T
points of halogermanes. Figures at curves are substance
nos. in Table 1; (12) SiH
and (13) SiJ