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Preparation of crystals of aluminum chloride
INORG. NUCL.
CHEM LETTERS
Vol. 6,
pp.
885-887,
1970.
Pergamon Press.
Printed in Great Britain.
PREPARATION OF CRYSTALS OF ALUMINL~d CHLORIDE
D.W. Seegmiller,
G.W. Rhodes, and L.A. King
F.J. Seller Research Laboratory (AFSC) and Department of Chemistry, United States Air Force Academy, Colorado 808~0
(Received 4 August 1970)
We have prepared single crystals of aluminum chloride ranging in size from a fraction of a millimeter
to several centimeters
long.
The method is
simple, relatively quick, and works equally well with milligram samples and samples weighing several grams.
Clusters of aluminum chloride crystals with
weights ranging from milligrams
to about one hundred grams also were prepared.
Crystals were grown both as a means of introducing aluminum chloride into experimental
vessels, and also as a method of purification.
are in the form of layers of hexagons (regular or elongated). parent, colorless,
and have a highly glossy appearance
The crystals
They are trans-
similar to mica.
The
layers are readily separable with a spatula blade, and easily can be obtained in paper thin sheets.
The crystals are hard in the plane of the hexagon, and
very difficult to grind into small pieces.
Even quite thick crystals are
flexible, and can be bent with the fingers.
Procedure Aluminum chloride Analyzed" an argon
aluminum stream.
crystals
chloride About
55 mm OD and 60 cm long.
were prepared
was first
purified
i n a two s t e p by repetitive
500 g of AlCl 3 was placed
process.
"Baker
sublimation
in one end of a Pyrex
in tube,
Five to i0 grams of granular aluminum or magnesium
turnings customarily were added to reduce any volatile ferric iron which might be present.
A slow stream of argon flowed through the tube.
Over a period of
approximately 8 hours, the Pyrex tube was passed through a tube furnace kept at 225°C.
The final sublimate,
a white free-flowlng powder, was collected in
a water cooled receiving tube which subsequently was transferred
into a glove
box. In the glove box, the desired amount of sublimed AICI 3 was transferred to a Pyrex vessel, closed at one end, in which the crystals were to be grown. 885
The
886
PREPARATION OF CRYSTALS OF ALUMINIUM CHLORIDE
tube then was removed from the glove box, evacuated, other end.
A representative
Vol. 6, No. 12
and sealed off at the
vessel is shown in Figure I.
Vessels
larger than
that shown, and also as small as 0. 5 mm ID and 6 cm long have been used successfully. The entire vessel was immersed in a bath of molten salt or silicone oil maintained at 210°C.
After the AICI s was '
entirely melted, the vessel was with-
r/_~ath
drawn from the bath over a period of several hours.
Crystals Level
The slower the vessel
was withdrawn the larger and better were the crystals obtained.
In any case, it
15 Cfll
35 mm
OO
is well to avoid a rate of withdrawal -- _-- - - ~
which results in the boiling of the AICI 3 melt.
I MeR
Boiling may provide sites
for the formation of many small crystals and may transport any soluble, nonvolatile impurities
from the liquid to
the crystals. The same technique was used to load experimental example:
apparatuses
viscosimeters)
FIG. 1
(for
with very pure AICIs, provided the entire apparatus
could be immersed in the bath.
In these instances,
the sublimed AICI s was
placed in a compartment of the apparatus which could be sealed off and removed after the crystals were grown. There was a small amount of dark colored residue left behind in the melt after the crystals were grown.
The existence of degradation products as the
source of this residue was discounted in the following manner:
A vessel was
constructed of three Pyrex bulbs connected in line by two segments of Pyrex tubing.
Sublimed AICI s was introduced into one of the terminal bulbs in the
manner described above.
The vessel was suspended vertically in a bath in such
a way that AICI s crystals were grown in the opposite terminal bulb. point
the bulb containing the original melt, and now showing evidence of the
dark residue, was sealed off and removed. the process repeated. bulb.
At this
The vessel then was inverted and
Now the crystals grew in what was formerly the middle
No trace of residue was apparent in the compartment which held the melt.
We must presume that impurities were introduced during the transfer operations in the glove box.
Vol. 6, No. 12
PREPARATION OF CRYSTALS OF ALUMINIUM CHLORIDE
887
Safety It is tempting to omit the sublimation step and load commercial AICI 3 directly into the crystal growing vessel.
Whenever we did this, we found that
enough gas was evolved to burst the Pyrex vessel when the AIC13 was heated.
CHEM LETTERS
Vol. 6,
pp.
885-887,
1970.
Pergamon Press.
Printed in Great Britain.
PREPARATION OF CRYSTALS OF ALUMINL~d CHLORIDE
D.W. Seegmiller,
G.W. Rhodes, and L.A. King
F.J. Seller Research Laboratory (AFSC) and Department of Chemistry, United States Air Force Academy, Colorado 808~0
(Received 4 August 1970)
We have prepared single crystals of aluminum chloride ranging in size from a fraction of a millimeter
to several centimeters
long.
The method is
simple, relatively quick, and works equally well with milligram samples and samples weighing several grams.
Clusters of aluminum chloride crystals with
weights ranging from milligrams
to about one hundred grams also were prepared.
Crystals were grown both as a means of introducing aluminum chloride into experimental
vessels, and also as a method of purification.
are in the form of layers of hexagons (regular or elongated). parent, colorless,
and have a highly glossy appearance
The crystals
They are trans-
similar to mica.
The
layers are readily separable with a spatula blade, and easily can be obtained in paper thin sheets.
The crystals are hard in the plane of the hexagon, and
very difficult to grind into small pieces.
Even quite thick crystals are
flexible, and can be bent with the fingers.
Procedure Aluminum chloride Analyzed" an argon
aluminum stream.
crystals
chloride About
55 mm OD and 60 cm long.
were prepared
was first
purified
i n a two s t e p by repetitive
500 g of AlCl 3 was placed
process.
"Baker
sublimation
in one end of a Pyrex
in tube,
Five to i0 grams of granular aluminum or magnesium
turnings customarily were added to reduce any volatile ferric iron which might be present.
A slow stream of argon flowed through the tube.
Over a period of
approximately 8 hours, the Pyrex tube was passed through a tube furnace kept at 225°C.
The final sublimate,
a white free-flowlng powder, was collected in
a water cooled receiving tube which subsequently was transferred
into a glove
box. In the glove box, the desired amount of sublimed AICI 3 was transferred to a Pyrex vessel, closed at one end, in which the crystals were to be grown. 885
The
886
PREPARATION OF CRYSTALS OF ALUMINIUM CHLORIDE
tube then was removed from the glove box, evacuated, other end.
A representative
Vol. 6, No. 12
and sealed off at the
vessel is shown in Figure I.
Vessels
larger than
that shown, and also as small as 0. 5 mm ID and 6 cm long have been used successfully. The entire vessel was immersed in a bath of molten salt or silicone oil maintained at 210°C.
After the AICI s was '
entirely melted, the vessel was with-
r/_~ath
drawn from the bath over a period of several hours.
Crystals Level
The slower the vessel
was withdrawn the larger and better were the crystals obtained.
In any case, it
15 Cfll
35 mm
OO
is well to avoid a rate of withdrawal -- _-- - - ~
which results in the boiling of the AICI 3 melt.
I MeR
Boiling may provide sites
for the formation of many small crystals and may transport any soluble, nonvolatile impurities
from the liquid to
the crystals. The same technique was used to load experimental example:
apparatuses
viscosimeters)
FIG. 1
(for
with very pure AICIs, provided the entire apparatus
could be immersed in the bath.
In these instances,
the sublimed AICI s was
placed in a compartment of the apparatus which could be sealed off and removed after the crystals were grown. There was a small amount of dark colored residue left behind in the melt after the crystals were grown.
The existence of degradation products as the
source of this residue was discounted in the following manner:
A vessel was
constructed of three Pyrex bulbs connected in line by two segments of Pyrex tubing.
Sublimed AICI s was introduced into one of the terminal bulbs in the
manner described above.
The vessel was suspended vertically in a bath in such
a way that AICI s crystals were grown in the opposite terminal bulb. point
the bulb containing the original melt, and now showing evidence of the
dark residue, was sealed off and removed. the process repeated. bulb.
At this
The vessel then was inverted and
Now the crystals grew in what was formerly the middle
No trace of residue was apparent in the compartment which held the melt.
We must presume that impurities were introduced during the transfer operations in the glove box.
Vol. 6, No. 12
PREPARATION OF CRYSTALS OF ALUMINIUM CHLORIDE
887
Safety It is tempting to omit the sublimation step and load commercial AICI 3 directly into the crystal growing vessel.
Whenever we did this, we found that
enough gas was evolved to burst the Pyrex vessel when the AIC13 was heated.