Raman scattering studies of the Ge-In sulfide glasses

Article abstract of DOI:10.1016/j.ssc.2005.12.032

Room temperature Raman scattering measurements of samples of the (1-x)GeS₂-xIn₂S₃ (x=0.00-0.35) system have been conducted together with the FTIR transmission spectra of partial samples. Based on the Raman scattering and FTIR transmission spectra of the prepared defect spinel polycrystalline In₂S₃, the additional peaks at 306 and 245 cm^-1 were ascribed to the local symmetric stretching vibration of InS₄ tetrahedra and InS₆ octahedra, respectively. According to the Raman scattering spectral evolution of the Ge-In sulfide glasses, the microstructure of the studied glasses was considered to be that S₃Ge-GeS₃ and S₃In-InS₃ ethane-like units originated from the sulfur deficient with the addition of In₂S₃ are homogeneously dispersed in a disordered polymer network formed by GeS₄, InS₄ tetrahedra and a small quantity of InS₆ octahedra interconnected by sulfur bridges.

Full text of DOI:10.1016/j.ssc.2005.12.032

Solid State Communications 137 (2006) 408–412
www.elsevier.com/locate/ssc
Raman scattering studies of the Ge–In sulfide glasses
Haizheng Tao , Shun Mao, Guoping Dong, Haiyan Xiao, Xiujian Zhao
* *
Key Laboratory of Silicate Materials Science and Engineering, Wuhan University of Technology, Ministry of Education,
22 Luoshi Road, Hongshan-Qu, Wuhan, Hubei 430070, People’s Republic of China
1
Received 20 July 2005; received in revised form 23 November 2005; accepted 21 December 2005 by B.-F. Zhu
Available online 13 January 2006
Abstract
2 2 3
Room temperature Raman scattering measurements of samples of the (1Kx)GeS –xIn S (xZ0.00–0.35) system have been conducted together
with the FTIR transmission spectra of partial samples. Based on the Raman scattering and FTIR transmission spectra of the prepared defect spinel
K1
polycrystalline In
2 3 4
S , the additional peaks at 306 and 245 cm were ascribed to the local symmetric stretching vibration of InS tetrahedra and
InS octahedra, respectively. According to the Raman scattering spectral evolution of the Ge–In sulfide glasses, the microstructure of the studied
6
glasses was considered to be that S
3
Ge–GeS
3
and S In–InS
3
3
ethane-like units originated from the sulfur deficient with the addition of In
2
S
3
are
homogeneously dispersed in a disordered polymer network formed by GeS
by sulfur bridges.
4 4 6
, InS tetrahedra and a small quantity of InS octahedra interconnected
q 2005 Elsevier Ltd. All rights reserved.
PACS: 78.30.-j; 78.40.Fy; 63.20.Pw
Keywords: A. Chalcogenide glasses; D. Microstructure; E. Raman scattering
1
. Introduction
microstructure of the (1Kx)GeS –xIn S pseudo-binary
2 2 3
glasses through the Raman scattering and FTIR technique.
Recently, Ga S -based chalcogenide glasses have attracted
2
3
much attention because of their possible applications such as
ultra-fast all optical switching, rare-earth doped 1.3 mm fiber
amplifier and, etc. [1–4]. In addition, based on the similarity of
chemical properties with Ga and In, it can be anticipated that
In S -based chalcogenide glasses also be the leading candi-
2
. Experimental procedure
The samples were prepared from particular high-purity
elements (at least 99.9%) using the 10 mm inner-diameter
silica tube by conventional melt-quenching techniques. For
details see the Refs. [5,6].
2
3
dates in the above-mentioned fields. However, to our best
knowledge, there are rare reports about the microstructure of
In S -based chalcogenide glasses. Considering the intimate
Chemical compositions of the samples were analyzed using
an energy-dispersive XRF analyzer. Homogeneity and
amorphous characteristics of the prepared materials were
confirmed by optical and electron microscopy and X-ray
2
3
relations among the above-mentioned applications, micro-
structure and basic properties of materials, understanding and
utilization of the basic studying findings are worthwhile from
theoretical and practical viewpoints.
diffraction (XRD) with Cu K radiation.
a
Raman scattering (RS) and Fourier-transform infrared
FTIR) transmission spectra were recorded at room tempera-
The understanding and utilization of the microstructure of
the Ge–In sulphide glasses is a key clue to further elucidating
the short range order of the In S -based chalcogenide glasses.
(
ture. The Raman measurements were performed in a 1808
backscattering geometry using an inVia Laser Confocal Raman
Microscope made by Renishaw PLC. The 632.8 nm line of
a He–Ne laser was used and the spectral resolution was of the
2
3
The main objective of this work was to study the
K1
*
Corresponding authors. Tel./fax: C86 27 87669729.
E-mail addresses: taohaizheng@hotmail.com (H.Z. Tao), opluse@mail.
order of 1 cm . For the avoidance of local laser damage that
could easily occur under the microscope and could locally
crystallize the amorphous samples, a laser power not exceeding
an approximate level of 2 mW was used. FTIR transmission
spectra were recorded using a Nicolet Nexus Fourier-transform
whut.edu.cn (X.J. Zhao).
0038-1098/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.ssc.2005.12.032

H.Z. Tao et al. / Solid State Communications 137 (2006) 408–412
409
compositions except for negligible losses in sulfur concen-
tration. So, hereinafter, the glass composition was expressed by
the batch composition. Glass formation seemed to be limited
to the range of xZ0.00–0.30 and several attempts made to
prepare a glass with higher In S content failed. According to
2
3
the XRD pattern, only the polycrystalline In S separates out
2
3
within the sample 10 (xZ0.35). In addition, this sample is very
inhomogeneous to the eye and several types of Raman spectra
were obtained under the assistance of the microscope (Fig. 1).
Fig. 2 represents the Raman spectra of the (1Kx)GeS –xIn S
2 3
2
glasses (sample 0–9). Five spectral changes can be extracted
following the addition of In S into the GeS glass. First, in
2
3
2
K1
K1
the region 100–200 cm , the little prominence at 150 cm
is gradually enhanced with the increased content of In S .
K1
Secondly, in the region 200–270 cm , a clear spectral
2
3
evolution about the location of the dominating peak from
K1
255 to 245 cm
increasing about the intensity of the shoulder at about
can be seen going with the gradual
K1
25 cm . The third change is about the increasingly
Fig. 1. Several sorts of typical Raman spectra of the sample 10 (0.65GeS
2
–
2
enhancement of the peak at 306 cm
0
.35In ) under the microscope.
2
S
3
K1
K1
in the 270–320 cm
K1
range. Fourthly, the strongest peak at 340 cm is broadened
little by little towards two sides with the increased content of
In S . And the descending scattering intensity by inchmeal of
infrared spectrometer under the N gas atmosphere. Each FTIR
2
spectrum is the average of 64 scans at a spectral resolution of
K1
cm . The samples were ground, then dispersed in CsI, and
4
pressed at 5 kPa into pellets to obtain far-infrared spectra in
2 3
K1
the shoulder at 370 cm is the final change originated from
the addition of In S . To further attain the micro-structural
K1
the range 200–600 cm
.
2 3
information, the FTIR transmission spectra of the glassy
samples (xZ0.00–0.25) were presented in Fig. 3. However, no
distinct spectral transformations are found except for the
3
. Results
Samples with x up to 0.3 were confirmed to be optically
homogeneous and transparent glasses to the eye and according
gradual descending of the characteristic absorption band of
K1
the GeS
glass at 377 cm
.
2
Finally, polycrystalline In S was synthesized by direct
2 3
to the methods given above. And these (1Kx)GeS –xIn S
2 3
reaction of a stoichiometric mixture of the elements using the
melt-quenching slowly method. The reaction led to a reddish
powder that X-ray powder diffraction showed to be the pure
defect spinel phase In S (JCPDF No: 84-1385). The Raman
2
(
xZ0.00–0.30) glasses changed from pale yellow through tint
red to deep red in color with the addition of In S . Based on the
2
3
XRF analysis, the final glasses preserved their initial nominal
2
3
2 2 3
Fig. 2. Raman spectra of the (1Kx)GeS –xIn S glasses. 0, xZ0.00; 1, xZ0.01; 2, xZ0.025; 3, xZ0.04; 4, xZ0.07; 5, xZ0.10; 6, xZ0.15; 7, xZ0.20; 8,
xZ0.25; 9, xZ0.30.

410
H.Z. Tao et al. / Solid State Communications 137 (2006) 408–412
2 2 3
Fig. 3. FTIR spectra of the (1Kx)GeS –xIn S glasses. 1, xZ0.00; 2, xZ0.05; 3, xZ0.10; 4, xZ0.15; 5, xZ0.20; 6, xZ0.25.
and FTIR spectra of this polycrystalline sample were shown in
Fig. 4. Group theoretical treatment of the spinel structure yields
four infrared active modes of species F1u and five Raman active
ones, one each species A1g and E , three of species F [7].
because of the breakdown of the translation symmetry. And
this can be confirmed by the random distribution of indium on
the octahedral and tetrahedral sites according to the JCPDF
card together with the corresponding absorption bands of the
FTIR spectrum.
g
2g
According to the research of Lutz et al. [7,8], the Raman peak
K1
at 366 cm
ascribed to the A1g mode, the peak at 262 cm to the E mode,
of the prepared polycrystalline In S can be
K1
In terms of our previous study [9], the A1g breathing mode
K1
2
3
of GaS tetrahedra locates at about 342 cm
4
in the GeS2–
g
K1
and the peaks at 117,179,322 cm to the F2g mode. As to the
Ga S pseudo-binary glassy system. Based on the similarity of
2 3
K1
additional peaks at 306 and 245 cm , which are stronger than
chemical properties for Ga and In located in the same main
family, it is reasonable to presume the same force constants
among the GaS and InS tetrahedra. According to the theory
the Raman active modes originated from the spinel structure, it
can be rationally presumed that these two additional peaks are
so-called clustering modes caused by high density of states of
distinct phonon branches at qs0, which is Raman allowed
4
4
of molecular vibration [10], then, the A1g breathing mode of
K1
InS tetrahedra should locate at about 315 cm considering
4
2 3
Fig. 4. Raman and FTIR transmission (CsI plate) spectra of the polycrystal In S sample.

H.Z. Tao et al. / Solid State Communications 137 (2006) 408–412
411
the bigger weight of In compared with Ga. Furthermore,
considering the less force constant of In-S bonds compared
with Ga–S ones, the A1g mode of InS tetrahedra should locate
Now let us see the spectral evolution of the (1Kx) GeS2–
xIn S glasses (xZ0–0.3). Firstly, the clear evolution of the
region 270–320 cm from a small shoulder to a distinct peak at
2
3
K1
4
K1
K1
at the lower wave number than 315 cm . So it is rational to
K1
306 cm
gives the direct proof about the existence of InS4
attribute the additional peak at 306 cm
stretching vibration of InS tetrahedra.
to the symmetric
tetrahedra within the Ge–In sulfide glassy net. In addition,
following the addition of In S , the similar transformation of the
4
2 3
K1
region 225–255 cm from a small prominence to a dominating
According to the analysis about the Raman spectra of
inverse and partially inverse indium sulfide spinels, Lutz
et al. [7] ascribed the bands in the range 240–255 to the A1g
breathing mode based on the facts that the intensity of this
band increases with increase in the degree of inversion of
K1
K1
peak at 245 cm within the region 200–270 cm indicates
another coordination surroundings of In atoms, viz. InS6
octahedra. And the weaker scattering strength of the prominence
K1
K1
at 245 cm compared with that of another one at 306 cm
manifests itself that the added indium exists mainly in the form of
the spinels. So it is reasonable to ascribed Raman peak at
K1
2
45 cm
to the symmetric stretching vibrating of InS6
InS tetrahedra. Secondly, the incremental quantity of the ethane-
4
octohedra.
. Discussion
The Raman spectrum of the compound GeS glass in Fig. 1
like units S In–InS with the addition of In S within the glassy
3
3
2 3
net can be confirmed by the gradual enhancement of the
K1
characteristic bands at about 150 and 225 cm together with
K1
the slowly broadening of the main peak at 340 cm toward
4
lower wave number aspect originated from another diagnostic
K1
2
(
can be distinctly observed at 115, 340 (A ), 370 (A ) and
0) is similar to those reported previously [11–13]. Four bands
c
band at 321 cm of the S In–InS units. Thirdly, the far weaker
3 3
K1
intensity of the prominence of the band at about 225 cm
K1
compared with that of another one at 255 cm gives us the
1
1
K1 K1
31 cm . The broad band at 115 cm , superimposed on the
4
high frequency tail of the boson peak, was ascribed ordinarily
information that the ethane-like units S
being more preferentially than another similar units S
when sulfur is deficient due to the addition of In . And the
Ge–GeS
comes into
3
3
to the bond bending motions of S atoms in GeS tetrahedra,
4
3
In–InS
3
while Kotsalas, etc. [11] suggested that considerable contri-
bution to this band may arise from intermolecular displace-
ments of whole GeS structural units. The bands at 340 and
S
2 3
K1
gradually widening of the main peak at 340 cm toward the
higher wave number aspect from sample 0–9 can be explained
from the gradual enhancement of another characteristic band at
4
K1
3
undoubtedly to the A symmetric stretching vibrations of GeS4
70 cm are strongly polarized and the former is attributed
K1
about 360 cm [12] of the ethane-like units S Ge–GeS . Lastly,
3 3
1
tetrahedra, while the latter is due to the symmetric stretch
vibrations of S atoms in bridges of edge-sharing (GeS
the descending scattering intensity by inchmeal of the shoulder at
K1
)
/2 4
370 cm isduetothedescendingamountofbridgedunits Ge
originated from the increasingly enhanced quantity of other units
(e.g. InS and InS , etc.) following the addition of In
2 6
S
1
K1
tetrahedra. The shoulder at 431 cm is relatively depolarized
c
(
to the A and A bands) and generally recognized to be due to
1
4
6
S .
2 3
1
the S–S and/or multi-sulfur bonds although there were some
controversies [14]. And this gives a probable existence of small
S–S chains in g-GeS2 either as separate molecular units
5. Conclusion
(
inhomogeneities) or as interconnecting units between GeS
4
K1
The Raman scattering and FTIR transmission spectra of the
prepared polycrystalline In S that belongs to the defect spinel-
type structure was reported. The additional peaks at 306 and
units. In addition, the very weak Raman band at 255 cm (can
be attributed to the vibrational mode of the ethane-like units
S Ge–GeS ; and only can be seen clearly through local
2
3
3
3
K1
245 cm
vibrating of InS and InS microstructural units respectively.
were attributed to the local symmetric stretching
magnification of Raman spectra) give another proof that the
microstructure of the stoichiometric GeS2 glass does not
consist only of GeS tetrahedra.
4
6
The inhomogeneous nature of sample 10 (0.65GeS2–
.35In S ) was clearly confirmed by the Raman scattering
4
0
2
3
According to the Fig. 1, the spectrum 1 exactly corresponds
to the Raman spectra of the prepared polycrystalline In2S3
which further verified the result of the XRD analysis. As to the
spectrum 4, the characteristic bands of the S In–InS ethane-
measurement. Based on the spectral evolution of the (1Kx)
GeS –xIn S glasses, the following micro-structural infor-
mation can be deduced:
2
2 3
3
3
like units can be clearly distinguished based on the distinct
K1
(
1) The added indium exists mainly in the form of InS4
tetrahedra together with a small quantity of InS octahedra
broad peak at about 153 cm
shoulders at about 226 and 321 cm
together with the small
K1
6
[15]. In addition, the
is due to the symmetric stretching
K1
within the glassy network.
2) With the addition of In S , the ethane-like units S Ge–
K1
main peak at 340 cm
mode of GeS and the small prominence at about 255 cm
(
2
3
3
4
GeS are more preferentially formed than the similar S In–
3
3
can be ascribed to the vibrating of the S Ge–GeS ethane-like
3
3
InS units.
3
K1
units. Furthermore, the bands at 306 and 244 cm
attributed to the symmetric stretching vibrations of InS and
can be
Acknowledgements
4
InS6 units, respectively, based on the above-mentioned
ascription. Lastly, the spectra 2 and 3 are intervenient between
the spectrum 1 and 4.
This work was partially funded by the National Natural
Science Foundation of China (No. 50125205), the Opening

412
H.Z. Tao et al. / Solid State Communications 137 (2006) 408–412
Fund of Key Laboratory of Silicate Materials Science and
Engineering (Wuhan University of Technology) Ministry of
Education (No. SYSJJ2004-14) and Scientific Research
Foundation of Wuhan University of Technology.
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[
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Sci. Ed. 20 (2005) 8.
[
10] Y.X. Zhongben, Infrared and Raman Spectra of Inorganic and Coordination
Compounds, Chemical Industrial Press, Beijing, 1991. p. 560.
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