Ultrapurification of 76Ge-enriched GeH4 by distillation

Article abstract of DOI:10.1134/S0020168511070016

⁷⁶Ge-enriched germane has been ultrapurified by low-temperature distillation. The nature and concentration of molecular impurities in the germane samples were determined by gas chromatography/mass spectrometry, high-resolution Fourier transform IR spectroscopy, and gas chromatography. The distillate contains no more than 10^-5 mol % hydrocarbons, 10 ^-4 mol % carbon dioxide, 10^-3 to 10^-1 mol % digermane and trigermane, and <3 × 10^-5 mol % other impurities. A distinctive feature of the impurity composition of the isotopically enriched germane samples is the presence of silicon tetrafluoride and sulfur hexafluoride impurities. Pleiades Publishing, Ltd., 2011.

Full text of DOI:10.1134/S0020168511070016

Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.
ISSN 0020ꢀ1685, Inorganic Materials, 2011, Vol. 47, No. 7, pp. 694–696. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © S.A. Adamchik, A.D. Bulanov, P.G. Sennikov, M.F. Churbanov, A.Yu. Sozin, O.Yu. Chernova, I.A. Kosheleva, O.Yu. Troshin, 2011, published in Neorganꢀ
icheskie Materialy, 2011, Vol. 47, No. 7, pp. 777–779.
Ultrapurification of 76GeꢀEnriched GeH4 by Distillation
S. A. Adamchik, A. D. Bulanov, P. G. Sennikov, M. F. Churbanov, A. Yu. Sozin, O. Yu. Chernova,
I. A. Kosheleva, and O. Yu. Troshin
Institute of Chemistry of HighꢀPurity Substances, Russian Academy of Sciences,
ul. Tropinina 49, Nizhni Novgorod, 603950 Russia
eꢀmail: bulanov@ihps.nnov.ru
Received November 15, 2010
Abstract
—
76Geꢀenriched germane has been ultrapurified by lowꢀtemperature distillation. The nature and
concentration of molecular impurities in the germane samples were determined by gas chromatography/mass
spectrometry, highꢀresolution Fourier transform IR spectroscopy, and gas chromatography. The distillate
contains no more than 10–5 mol % hydrocarbons, 10–4 mol % carbon dioxide, 10–3 to 10–1 mol % digermane
and trigermane, and <3
×
10–5 mol % other impurities. A distinctive feature of the impurity composition of
the isotopically enriched germane samples is the presence of silicon tetrafluoride and sulfur hexafluoride
impurities.
DOI: 10.1134/S0020168511070016
INTRODUCTION
trifugal isotope enrichment of germane, a process proꢀ
posed by Aref’ev et al. [8], may be responsible for the
specific features of the impurity composition of gerꢀ
mane.
In this paper, we report ultrapurification of
76Geꢀenriched germane by distillation and its impurity
composition.
Highꢀpurity germanium is used in the fabrication
of IR optical components, highꢀresolution nuclear
detectors, thinꢀfilm silicon/germanium structures for
photoelectric converters, and other devices. Germaꢀ
nium isotopes possess a number of unique properties.
In particular, 76Ge is a potentially attractive detector
material for neutrinoless double beta decay experiꢀ
ments [1, 2].
EXPERIMENTAL
One effective way to produce highꢀpurity germaꢀ
nium is the hydride route, which relies on the thermal
decomposition of germane after ultrapurification.
There has been considerable effort devoted to the
physicochemical principles of the preparation and
analysis of highꢀpurity germane and the germanium
isolated from it [3, 4]. Fractional distillation has been
demonstrated to be effective in the ultrapurification of
germane of natural isotopic composition, and analytiꢀ
cal techniques with low detection limits have been
developed for a wide range of molecular impurities in
germane.
The techniques used to determine the impurity
composition of germane include gas chromatography
(GC), gas chromatography/mass spectrometry
(GC/MS), and, occasionally, highꢀresolution laser
diode IR spectroscopy [5–7]. These techniques allow
one to detect hydrogen, С1–С4 hydrocarbons, their
fluorinated and chlorinated derivatives, inorganic
hydrides (AsH3 and PH3), water, alkyl derivatives of
germane, and chlorogermanes with low detection limꢀ
its, at a level of 10–6 to 10–5 mol %.
Germane ultrapurification was carried out by batch
distillation at a temperature of –85 С and pressure of
0.15 MPa, using a laboratoryꢀscale middleꢀfed stainꢀ
less steel column, with rectifying sections 40 and
70 cm in height and 2 cm2 in crossꢀsectional area, packed
°
with nichrome prismatic coils 2.5
× 2.5 × 0.2 mm in
dimensions. The germane charge weight was ~300 g. The
light and heavy fractions, enriched in less and more
volatile impurities, respectively, were simultaneously
taken from the top and bottom of the distillation colꢀ
umn at intervals. After each distillation cycle, the disꢀ
tillate was drawn off from the middle feed tank. The
yield of the purified product was 70%.
We studied different germane samples: germane of
natural isotopic composition (prepared by reacting
germanium tetrachloride with sodium borohydride)
purified by distillation (sample 1), germane enriched
in 76Ge to 88 at % by centrifugation (sample 2), and
the same germane purified by distillation (sample 3).
In addition, we isolated and investigated 76GeH4 fracꢀ
tions containing molecular impurities more and less
volatile than germane (samples 4 and 5, respectively).
Data on the ultrapurification and impurity compoꢀ
sition of isotopically enriched germane, including
The germane samples were analyzed for molecular
76GeH4, a substance of practical importance, are not impurities by GC/MS, GC, and highꢀresolution
available in the literature. At the same time, the cenꢀ (0.05 cm–1) Fourier transform IR spectroscopy as
694

Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.
ULTRAPURIFICATION OF 76GeꢀENRICHED GeH4 BY DISTILLATION
695
Impurity compositions of GeH4 samples as determined by GC/MS, GC, and IR spectroscopy
Mole percent
sample 3
Impurity
sample 1
sample 2
sample 4
sample 5
CH4
–
–
–
–
<1
<5
×
×
×
10–5
10–6
10–4
<5
<5
×
×
×
×
×
10–6
10–6
10–5
10–6 (6.5 0.8)
10–7 (1.5 0.2)
10ꢀ7 (3.0 0.5)
10ꢀ7 (1.0 0.2)
<5
<5
<1
×
×
×
×
×
×
×
×
×
10–6
10–6 (9.5 0.8)
10–5 (1.0 0.2)
10–4
10–4
10–5
10–4
10–2 (1.2 0.3)
10–2 (2.4 0.5)
(5 1)
×
×
×
×
×
×
×
×
×
10–5
C2H4
C2H6
C3H6
C3H8
10–4
10–4
10–6
10–7
10–7
10–7
10–6
10–6
(1.6 0.2)
–
<1
<1
<1
<8
<9
<9
<8
<9
×
10–7
10ꢀ7
10ꢀ7
<8
×
×
×
×
×
10–7
10–6
10–6
10–3
10–3
<8
n
ꢀC4H10
×
(3 1)
<9 ×
i
ꢀC4H10
<9
×
(6 1)
<9
×
C5–C9 hydrocarbons
<1
×
10–6 (1.5 0.2)
10–7 (1.5 0.2)
(7 2)
<2
×
10–6
10–7 (7.6 0.8)
(9 3)
Chlorinated and fluorꢀ
inated hydrocarbons
(9 4)
×
×
Alcohols, ethers
Alkylgermanes
Chlorogermanes
Polygermanes
<2
(5 2)
<1
×
×
×
×
×
×
×
10–6
10–5 (1.9 0.6)
10–6
(3 1)
10–3 (4.5 1.5)
10–3 (1.8 0.2)
10–5 (1.3 0.6)
10–5 (3.3 1.6)
–
<2
<2
<1
×
×
×
×
×
×
×
10–6
10–6
10–6
10–1
10–4 (3.3 0.4)
10–5
10–5
(5 1)
(7 2)
×
×
10–5
10–3
<2
(3 1)
(4 1)
(4 2)
×
×
×
×
×
×
×
10–6
10–6
10–3
10–3
10–2
10–1
10–2
×
×
×
×
×
×
10–4
10–1
5
2
(2.2 0.9)
(1.3 0.2)
<2
10–1 (1.6 0.6)
10–3 (4.0 0.6)
12
4
CO
×
×
×
10–3 (2.6 0.3)
10–5 (7.1 1.7)
10–5 (4.1 0.8)
2
SiF
10–2
10–3
<2
<3
<2
<3
4
SF
<3
6
76
Note: Sample 1, GeH of natural isotopic composition, purified by distillation; sample 2, GeH enriched by centrifugation; sample 3,
4
4
76
76
76
GeH purified by distillation; sample 4, the GeH fraction taken from the bottom of the column; sample 5, the GeH fracꢀ
4
4
4
tion taken from the top of the column.
described elsewhere [7, 9]. Samples for analysis were carbons, aromatic hydrocarbons, alcohols and ethers,
taken from the gas phase. The analysis results for the germane homologues, alkyl derivatives of germane,
GeH4 samples are presented in the table.
and chlorogermanes.
The spectroscopically detected SiF4 and SF6 are
atypical of germane of natural isotopic composition.
The presence of these impurities in the isotopically
enriched sample is probably associated with the
“memory” of the centrifuge cascade, which was previꢀ
ously used to separate silicon and sulfur isotopes. SF6
and CO2 are concentrated in the light fraction even
though they should be considered lowꢀvolatile accordꢀ
ing to their boiling points. One possible reason for this
behavior of CO2 and SF6 impurities in germane is that,
at the distillation parameters used, they form a solid
phase in the condenser of the column. Its sublimation
leads to an increased content of these impurities in the
overhead fraction.
RESULTS AND DISCUSSION
The data in the table demonstrates that, as a result
of 76Ge enrichment, С4–С9 hydrocarbons, chlorinated
and fluorinated hydrocarbons, chlorogermanes, alkyꢀ
lgermanes, and polygermanes are concentrated in the
germane. The contents of different groups of impuriꢀ
ties in the enriched germane range widely, from 10–7 to
10–1 mol %. Clorogermane and digermane are present
in the highest concentrations, at a level of 10–1 mol %.
Distillation effectively reduces the contents of all
the molecular impurities detected. The contents of
36 impurity species in the distillate are within
10–5 mol %. The highest contents are those of polygerꢀ
manes (10–1 mol % digermane and 10–4 mol % trigerꢀ
mane) and carbon dioxide (
10–4 mol %). The conꢀ
tent of ethane, the most difficult to remove impurity
= 1.21 0.03 [3]), in the distillate (<1
10–5 mol %)
is more than one order of magnitude lower than its iniꢀ
tial content (1.6
10–4 mol %). The C1 and C2 hydroꢀ
1
×
In all of the samples studied, the 76Ge2H6O (gerꢀ
manoxane), SiH4 (silane), and CO (carbon monoxide)
contents were below the detection limits of IR spectrosꢀ
6
×
4
×
copy for these impurities (1
×
10–4 to 1 10–3 mol %).
×
(
α
×
×
CONCLUSIONS
Highꢀpurity 76Geꢀenriched germane has been preꢀ
carbons (methane, ethane, and ethylene) are concenꢀ
trated in the overhead (light fraction). All of the other
impurities detected are concentrated in the bottom pared by distillation. The distillate contains no more
fraction: saturated hydrocarbons having more than than 10–5 mol % hydrocarbons, 10–4 mol % carbon
two carbon atoms, chlorinated and fluorinated hydroꢀ dioxide, 10–3 to 10–1 mol % digermane and trigerꢀ
INORGANIC MATERIALS Vol. 47
No. 7 2011

Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.
696
ADAMCHIK et al.
5. Krivtsun, V.M., Kuritsyn, Yu.A., Snegirev, E.P., et al.,
Measurement of Low PH3 Concentrations in GeH4 with
a TunableꢀLaserꢀDiode Spectrometer, Zh. Prikl. Spekꢀ
trosk., 1985, vol. 63, pp. 571–576.
mane, and <3
×
10–5 mol % other impurities. A disꢀ
tinctive feature of the impurity composition of the isoꢀ
topically enriched germane samples is the presence of
silicon tetrafluoride and sulfur hexafluoride impuriꢀ
ties.
6. Devyatykh, G.G., Zasavitskii, I.I., Il’in, V.M., et al.,
TunableꢀLaserꢀDiode IR Spectrometer for Molecular
Analysis of HighꢀPurity Volatiles, Vysokochist. Veshꢀ
chestva, 1990, no. 6, pp. 106–114.
REFERENCES
1. Schoenert, S., The GERmanium Detector Array
(GERDA) for the Search of Neutrinoless Beta Beta
Decays of Geꢀ76 at LNGS, Nucl. Phys. Proc. Suppl.,
2005, vol. 145, pp. 242–245.
2. Aalseth, C., Anderson, D., Arthur, R., et al., The Proꢀ
posed Majorana Geꢀ76 DoubleꢀBeta Decay Experiment,
Nucl. Phys. Proc. Suppl., 2005, vol. 138, pp. 217–220.
3. Devyatykh, G.G. and Zorin, A.D., Letuchie neorganꢀ
icheskie gidridy osoboi chistoty (Ultrapure Volatile Inorꢀ
ganic Hydrides), Moscow: Nauka, 1974.
4. Devyatykh, G.G, Gusev, A.V., and Vorotyntsev, V.M.,
Preparation of HighꢀPurity Germanium, Vysokochist.
Veshchestva, 1988, no. 1, pp. 5–16.
7. Krylov, V.A., Chernova, O.Yu., Kireev, S.M., et al.,
Determination of Impurities in HighꢀPurity Germane by
Gas Chromatography/Mass Spectrometry, Perspekt.
Mater., 2008, no. 6, pp. 227–229.
8. Aref’ev, D.G., Vasin, S.A., Dolgov, S.G., et al., Applicaꢀ
tion of Germane for Germanium Isotope Separation in
Gas Centrifuges, Perspekt. Mater., 2010, no. 8, pp. 19–24.
9. Sennikov, P.G., Kotkov, A.P., Adamchik, S.A., et al.,
Impurities in Monosilanes Synthesized by Different Proꢀ
cesses, Neorg. Mater., 2010, vol. 46, no. 4, pp. 415–420
[Inorg. Mater. (Engl. Transl.), vol. 46, no. 4, pp. 358–
363].
INORGANIC MATERIALS Vol. 47
No. 7
2011