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Formation and study of electrically conductive layers of copper sulfdes formed on the polyamide surface by the use of potassium pentathionate

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Semiconductive and electrically conductive layers of copper sulfdes on the polyamide 6 (PA) surface were formed using the sorption-difusion method and a water solution of potassium pentathionate, K 2S 5O 6, as a precursor of polymer sulfurization. Pentathionate anions containing chains of divalent sulfur atoms of low oxidation state, -O 3S-S-S-S-SO 3-, are sorbed-difused into PA flms if they are treated with K 2S 5O 6 solution. Te concentration of sorbed sulfur increases with an increase of the temperature and concentration of the precursor solution and the duration of PA treatment. Cu xS layers are formed on the surface of PA flm when a sulfurized polymer is treated with the water solution of copper(II/I) salt: pentathionate anions react with copper ions. Te concentration of copper increases (up to ∼40 mg · g -1) with increasing the concentration and temperature of the precursor solution. XRD results confrmed the formation of Cu xS layers on the surface of PA. Te phase composition of Cu xS layer depends on the concentration and temperature of potassium pentathionate solution and on the duration of initial treatment in the K 2S 5O 6 solution. Te layers are composed of the low-conductive tetragonal chalcocite, Cu 1.96S, monoclinic djurleite, Cu 1.9375S, electrically conductive rhomhedral digenite, Cu 9S 5, orthorhombic ani-lite, Cu 7S 4, and cubic CuS 2. Te phase composition determines the electrical characteristics of the layers obtained: the sheet resistance varies from 0.104 to 1.52 · 10 3 KΩ/□. X-ray photoelectron spectroscopy confrmed formation of copper sulfdes of various phases. Te regularities established in the present work enable formation of Cu xS layers of a desirable composition and conductivity.
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CHEMIJA. 2009. Vol. 20. No. 1. P. 45–55
© Lietuvos mokslų akademija, 2009
© Lietuvos mokslų akademijos leidykla, 2009
Formation and study of electrically conductive layers of
copper sulfides formed on the polyamide surface by
the use of potassium pentathionate
Vitalijus Janickis1*,
Remigijus Ivanauskas1,
Rūta Stokienė1,
Mindaugas Andrulevičius2
1 Kaunas University of Technology,
Radvilėnų 19,
LT-50254 Kaunas, Lithuania
2 Institute of Physical Electronics
of Kaunas University of Technology,
Savanorių 271,
LT-50131 Kaunas, Lithuania
* Corresponding author. E-mail: vitalijus.janickis@ktu.lt
Semiconductive and electrically conductive layers of copper sulfides on the polyamide 6
(PA) surface were formed using the sorption–diffusion method and a water solution of
potassium pentathionate, K2S5O6, as a precursor of polymer sulfurization. Pentathionate
anions containing chains of divalent sulfur atoms of low oxidation state, O3S–S–S–S–SO3
,
are sorbed-diffused into PA films if they are treated with K2S5O6 solution. e concentra-
tion of sorbed sulfur increases with an increase of the temperature and concentration of the
precursor solution and the duration of PA treatment. CuxS layers are formed on the surface
of PA film when a sulfurized polymer is treated with the water solution of copper(II / I)
salt: pentathionate anions react with copper ions. e concentration of copper increases
(up to ~40 mg · g–1) with increasing the concentration and temperature of the precursor
solution. XRD results confirmed the formation of CuxS layers on the surface of PA. e
phase composition of CuxS layer depends on the concentration and temperature of potas-
sium pentathionate solution and on the duration of initial treatment in the K2S5O6 solution.
e layers are composed of the low-conductive tetragonal chalcocite, Cu1.96S, monoclinic
djurleite, Cu1.9375S, electrically conductive rhomhedral digenite, Cu9S5, orthorhombic ani-
lite, Cu7S4, and cubic CuS2. e phase composition determines the electrical characteristics
of the layers obtained: the sheet resistance varies from 0.104 to 1.52 · 103 K / . X-ray
photoelectron spectroscopy confirmed formation of copper sulfides of various phases. e
regularities established in the present work enable formation of CuxS layers of a desirable
composition and conductivity.
Key words: potassium pentathionate, polyamide, copper sulfide layer
INTRODUCTION
Dielectrics (including polymers) with layers of copper chal-
cogenides have attracted the interest of researchers first of all
because of their importance for solar energy elements and
converters [1, 2]. In this line of investigation, we explore the
possibility to associate at the nanometric scale layered sol-
ids such as copper sulfides with functional semihydrophilic
polymers, mainly isolators. Various polymers modified with
copper sulfide films on their surface represent a new class of
materials – composites with novel combinations of proper-
ties. Copper sulfide is an interesting material for its metal-
like electrical conductivity [3] and ideal characteristics for
solar energy absorption [4]. erefore, films of copper sulfide
on polymers are used as conductive substrates for metal
deposition [5, 6] and semiconductors [7], as polarizers of in-
frared radiation [8], as active absorbents of radio waves [9].
Due their optical properties, CuxS thin films find use in many
photovoltaic and photothermal applications [10].
Hydrophilic and semi-hydrophilic polymers are capable
of absorbing ions of various electrolytes from aqueous solu-
tions [11]. Over the last decade, the sorption–diffusion me-
thod for the formation of thin copper sulfide layers on the
surface of polyamide 6 (PA), based on the initial treatment
of a polymer with the solutions containing anions of poly-
thionates, SnO6
2–, has been under extensive investigation at
the Department of Inorganic Chemistry of the Kaunas Uni-
versity of Technology. It was assumed that during treatment
Vitalijus Janickis, Remigijus Ivanauskas, Rūta Stokienė, Mindaugas Andrulevičius
46
the polythionate ions containing chains of divalent sulfur
atoms of low oxidation state, O3S–Sx–SO3
[12–14], are
sorbed by a polymer.
in layers of copper sulfides are formed on PA surface
if a sulfurized polymer is later treated with a solution of
copper(II / I) salts [15–17].
In earlier studies using this method, a PA film had been
first treated with a water solution of higher polythionic acid,
H2SnO6 (n = 9–33) [15–18]. A disadvantage of this method,
however, is that the synthesis of highly sulfurized polythionic
acids from the hydrogen sulfide, H2S, sulfurous, H2SO3, a nd
thiosulfuric, H2S2O3, acids is rather complicated and lasts up
to two days [19]. Besides, a gradual spontaneous decompo-
sition of these acids with the liberation of elemental sulfur
occurs with time [20]; also, acid solutions exert a specific ef-
fect on the structure of PA [21].
e aim of the present work was to summarize, review
and discuss the results obtained by us while studying the pro-
cess of pentathionate ions sorption–diffusion into PA, also
processes of the formation of copper sulfide layers in the sur-
face of PA films, and to characterize the copper sulfide layers
obtained, since only separate fragments of these studies were
described in our previous publications [22–25]. e chemical
and phase composition of CuxS layers, their electrical con-
ductance were studied by the methods of atomic absorption
spectroscopy, X-ray diffraction, X-ray photoelectron spec-
troscopy (XPS) and by measuring electrical sheet resistance.
EXPERIMENTAL
A PA 6 film (specification TY 6-05-1775-76, grade PK-4,
70 µm thick), produced in Russia, was used. Prior to the ex-
periments, pieces of the film 15 × 70 mm in size had been
boiled in distilled water for 2 h to remove the remainder of
the monomer. en they were dried with filter paper and kept
in a dessicator over CaCl2 for 24 h.
Potassium pentathionate hemitrihydrate, K2S5O6 · 1.5H2O,
was produced by the method of Kurtenacker [26].
PA films were sulfurized in a thermostatic vessel, using
a continually stirred acidified (0.1 mol · dm–3 HCl, pH ~ 1.5)
0.025–0.2 mol · dm–3 K2S5O6 solutions for up to 6 h at a tem-
perature of 1–20 °C. Such interval of concentration was cho-
sen because of the stability of potassium pentathionate in a
solution. Preliminary experiments had shown that the sorp-
tion from the solutions of a lower concentration was too slow
and insufficient, and at a higher concentration the stability of
K2S5O6 decreased significantly. e stability of pentathionate
solution at temperatures higher than 20 °C was insufficient,
either.
At certain time intervals, the PA film samples were re-
moved from K2S5O6 solution, rinsed with distilled water,
dried with filtration paper, le over CaCl2 for 24 h and then
used in further experiments and analysis.
Sulfur concentration (Cs) in PA film samples was de-
termined potentiometrically [27]. First, a sample of a sul-
furized PA film was treated under heating with 10–15 ml of
10 mol · dm–3 KOH and diluted with the same amount of dis-
tilled water. Standard calomel and platinum electrodes were
used for the potentiometric titration of the solution obtained
in KOH with 0.05 N solution of iodine under stirring. For
potentiometric measurements, a pH-meter (pH–673 M mil-
livoltmeter) was used.
Aer immersion in K2S5O6 solution, a sample was treat-
ed with Cu(II / I) solution, then rinsed with distilled water,
dried over CaCl2, and used for analysis and subsequent ex-
periments. 0.4 mol · dm–3 Cu(II / I) salt solution was made
from crystalline CuSO4 · 5H2O and 0.1 mol hydroquinone
as a reducing agent. In this mixture, a ratio of univalent
and divalent copper salts, independently of temperature, at
0.34 mol · dm–3 Cu(II) salt and 0.06 mol · dm–3 Cu(I) salt is
present [28]. e concentration of copper in PA samples was
determined using an atomic absorption Perkin–Elmer spec-
trometer 503 (λ = 325 nm) [29].
e conductivity of copper sulfide films at the constant
current was measured using an E7-8 numerical measuring
instrument with special electrodes.
e UV, VIS (200–400 nm) and IR (400–1400 cm–1) spec-
tra were obtained with the aid of SpectronicR GenesysTM and
Perkin–Elmer GX spectrometers, system FT–IR.
e phase composition of the copper sulfide layer was
investigated by X-ray diffraction, using a DRON-6 diffracto-
meter (radiation Cu–Kα). X-ray diffractograms of PA samples
with CuxS layers were treated using the Search Match, Con-
vX, Xfit, and Microso Excel programs. XPS spectra of CuxS
layers were recorded with a ESCALAB MKII spectrometer
(VG Scientific, radiation Mg Kα 1253.6 eV, output 300 W).
e vacuum in the analysing chamber was kept at a level of
1.33 · 10–8 Pa, the distribution of elements in the depth was
determined by sputtering with an Ar+ gun with the ion ener-
gy of about 1.0 keV. e samples were etched in a preparation
chamber with the vacuum 9.3 · 10–3 Pa and current 20 µA;
the duration of etching was 30–180 s. e rate of eaching
was 1 nm / 30 s. e maximum accuracy of the method is
± 0.1 at. %. To investigate layers obtained by the XPS method,
the photoelectron spectra of Cu 2p3/2 and S 2p were recorded.
Empirical sensitivity factors for these elements were taken
from the literature [30], and the spectra obtained were com-
pared with the standard ones [31].
RESULTS AND DISCUSSION
e nature of sulfur-containing particles sorbed by a PA film
was studied by means of IR and UV absorption spectra of
polymer films treated in a potassium pentathionate solution.
We found that the peaks of most intensive bands in the IR
spectra of PA samples sulfurized in K2S5O6 solution, recorded
by the compensation method (PA absorption eliminated),
were in the intervals 418–484, 523–568, 609–737, 985–1079
and 1111–1284 cm–1. On the grounds of the literature data
[14, 32], the peaks in the first interval were assigned to the
47
Formation and study of electrically conductive layers of copper sulfides formed on the polyamide surface...
valence vibrations in the S–S bond (νS–S), in the second in-
terval to the asymmetric deformation O–S–O vibrations
δas(O–S–O), in the third interval to the symmetric deforma-
tion O–S–O vibrations, δs(O–S–O), in the fourth interval
to the symmetric valence S–O vibrations, νs(S–O), and in
the fih interval to the asymmetric valence S–O vibrations,
νas(S–O). ese results confirm that the sorption of penta-
thionate ions by PA occurs during polymer treatment with an
acidified solution of K2S5O6.
e UV absorption spectra of PA samples sulfurized for
different periods of time in K2S5O6 solution are shown in
Fig. 1. ree absorption maxima are observed in these spec-
tra: at 250 nm as an obvious shoulder, at 285 nm as a peak,
and at 325 nm as an unclearly defined shoulder.
According to data of a study of the UV absorption spec-
tra of lower potassium polythionates [33, 34], the absorption
maxima of pentathionate ions are most intensive at 256 and
295 nm. us, UV absorption spectra recorded by us confirm
again that sulfur is sorbed by PA films in the form of pentathio-
nate ions. e intensity of absorption maxima in the spectra,
as expected, increases with an increase in the duration of a
polymer treatment with potassium pentathionate solution.
Chemical analysis of PA samples sulfurized in a K2S5O6
solution showed that the concentration of sulfur sorbed by
a polymer increases with increasing the temperature (Fig. 2)
and concentration (Fig. 3) of the sulfurization solution.
en the chalcogenized PA samples were treated with a
water solution of Cu(II / I) salts. Changes of a PA tape ap-
pearance aer its treatment with Cu(II / I) solution indicated
formation of copper chalcogenide layers on the surface of
the polymer. e tapes from colourless transform into yel-
low, then into brown and acquire a metallic lustre. Electrical
Fig. 1. UV absorption spectra of PA lms sulfurized in acidied 0.05 mol · dm–3
K2S5O6 solution at a temperature of 10 °C for dierent periods of time. D uration
of PA sulfurization, h: 1 – 0.25, 2 – 1, 3 – 2, 4 – 3, 5 – 4, 6 – 5, 7 – 6
Fig. 2. Change of sulfur concentration in PA with time during its treatment with
acidied 0.05 mol · dm–3 K2S5O6 solution at dierent temperature. T, °C: 1 – 1;
2 – 10; 3 – 20
Fig. 3. Change of sulfur concentration in PA with time during its treatment with
acidied K2S5O6 solution of dierent concentration at a temperature of 10 °C.
Con centration of K2S5O6 solution, mol · dm–3: 1 – 0.025; 2 – 0.05; 3 – 0.1; 4 – 0.2
Vitalijus Janickis, Remigijus Ivanauskas, Rūta Stokienė, Mindaugas Andrulevičius
48
measurements finally confirmed that PA surface from the di-
electric became a semiconductor or an electrical conductor.
e conditions of initial chalcogenation determine the
concentration of copper and the chemical and phase com-
position of the chalcogenide layer formed: the concentration
of copper increases (up to ~40 mg · g–1) with increasing the
temperature and concentration of PA sulfurization precursor
solution (Figs. 4, 5).
CuxS layers of various composition are formed on the
surface of the polymer and in its bulk aer treatment of PA
samples with sorbed polythionate ions with copper(II / I)
solution. e phase composition of the formed layer was
established by comparing its X-ray diffraction patterns
with those of known copper sulfides [35–38]. e chemical
composition and crystal structure of the majority of CuxS
minerals such as chalcocite Cu2S, djurleite Cu1.95S, ya rro w-
ite Cu1.12S and covellite CuS were investigated. e crystal
structure of Cu
xS depends on the chemical composition
and the conditions of synthesis. e composition of CuxS
deposited by the sorption–diffusion method was scarcely
investigated.
Structural studies of CuxS layers formed by the sorp-
tion–diffusion method are limited by the polycrystallinity
of the layers obtained, as well as by the existence of CuxS
phases with various compositions and structures, and by
the crystallinity of PA. e intensity of the polymer peaks at
θ < 13° exceeds the intensity of copper sulfide peaks a few
times. erefore, the area of 2θ 26.0° was investigated in
more detail.
Aer treatment of PA samples with sorbed polythionate
anions for a different time in a copper salt solution at 80 °C,
CuxS films of different composition were obtained. X-ray dif-
fraction patterns of the films showed peaks of various copper
sulfide phases coexisting in a film (Figs. 6, 7).
e X-ray diffraction patterns of CuxS layers formed on
PA aer its sulfurization in K2S5O6 solutions of different con-
centration during 4 h at 10 °C are shown in Fig. 6. When the
0.025 and 0.05 mol · l–1 solutions of potassium pentathion-
ate had been used for polymer sulfurization, the peaks of
orthorhombic anilite, Cu1.75S, (72–617) at 2θ = 41.10, 48.50,
53.60, 58.40, 60.90° [35] and monoclinic djurleite, Cu1.9375S,
(71–1383) at 2θ = 34.40 and 38.20° [36] were detected
(Fig. 6, curves 1 and 2). e peak of an additional phase of
CuS2 (83–1619) at 2θ = 59.80° [37] was detected in CuxS lay-
ers formed on PA initially sulfured with 0.1 mol · dm–3 K2S5O6
solution (Fig. 6, curve 3). We noted that the number of more
conductive anilite peaks and their intensity increased with
increasing the concentration of the K2S5O6 solution used for
PA sulfurization: only one peak of djurleite at 2θ = 38.20°
[36] and thee peaks of anilite at 2θ = 37.60, 46.50 and 49.60°
[35] were found in the diffraction pattern of the CuxS layer
on PA sulfurized with 0.20 mol · dm–3 solution of K
2S5O6
(Fig. 6, curve 4).
Analysis of X-ray diffraction patterns of CuxS layers
formed on PA sulfured for 4 h with 0.1 mol · dm–3 K2S5O6
Fig. 4. Dependence of copper concentration in PA on the period of initial PA treat -
ment with acidied 0.05 mol · dm–3 K2S5O6 solution at dierent temperature.
Sulfurized PA was treated with a Cu(II / I) salt solution at 80 °C for 10 min. T, °C:
1 – 1; 2 – 10; 3 – 20
Fig. 5. Dependence of copper concentration in PA on the period of initial PA treat-
ment with acidied K2S5O6 solution of dierent concentration at a temperature of
10 °C. Concentration of K2S5O6 solution, mol · dm–3: 1 – 0.5; 2 – 0.1; 3 – 0.2
49
Formation and study of electrically conductive layers of copper sulfides formed on the polyamide surface...
solution at different temperatures showed
that their phase composition had changed
(Fig. 7). On treating PA samples with K2S5O6
solution at 1 °C, phases of poorly conductive
djurleite, Cu1.9375S (peak at 2θ = 38.2°), and
tetragonal chalcocite, Cu1.96S (29–578) [38]
(peak at 2θ = 48.8°) were detected (Fig. 7,
curve 1). When the temperature of K2S5O6
solution was raised up to 10 °C, the CuxS
layer consisted of three phases: monoclinic
djurleite, Cu1.9375S (2θ = 38.2°), more con-
ductive orthorhombic anilite, Cu7S4, (peaks
at 2θ = 49.4 and 64,7°) and conductive cu-
bic copper sulfide CuS2 (peak at 2θ = 59.8°)
(Fig. 7, curve 2). e further increase of the
PA film sulfurization temperature to 20 °C
resulted in the form atio n of a CuxS layer con-
sisting of four phases: monoclinic djurleite,
Cu1.9375S (peak at 2θ = 38.2°), orthorhom-
bic anilite, Cu7S4 (peaks at 2θ = 49.4, 50.5,
59.6 and 61.5°), tetragonal chalcocite, Cu1.96S
(2θ = 45.02°) and of more conductive rhom-
bohedral digenite, Cu9S5 (peak at 2θ = 60,1°)
(Fig. 7, curve 3).
Changes of the phase composition of
copper sulfide layers determine the electri-
cal conductivity of these layers. e sheet
resistance depends greatly on the conditions
of PA initial sulfurization (Table 1). When
the duration of PA initial chalcogenization
is prolonged and the concentration of chal-
cogenation solution is increased, the con-
ductivity of CuxS layers increases, too. It is
known [39] that the electrical resistance of
CuxS decreases 106 times when the value of x
changes from 2 to 1. In these conditions, the
stoichiometrical composition of CuxS chan-
ges in the direction of x decreases, resulting
in the formation of copper sulfide layers of
low electrical resistance (100 / ).
Table 1. Sheet resistance (k / ) of CuxS layers on PA lms rst treated with K2S5O6 solution and then with Cu(I / II) salt solution at 80 °C for 10 min
K2S5O6 solution Duration of sulfurization, h
Concentration,
mol · dm–3 Temperature, °C 0.25 0.50 1.00 2.00 3.00 4.00 5.00 6.00
0.025 1 1.52 · 10355.4 13.3 8.05
10 2.44 1.35 0.98 0.50 0.39
0.05
1 0.93 0.81
10 3.03 2.67 1.11 1.05
20 0.283 0.236 0.194 0.161 0.119
0.10
1 56.13 36.00 2.07
10 21.78 1.63 1.12 0.58 0.35
20 4.5 · 1022.2 0.457 0.227 0.127 0.122 0.104
0.20 10 985 2.34 0.80 0.391 0.273 0.298
Fig. 6. X-ray diraction patterns of CuxS layers on PA (peaks of djurleite (Cu1.9375S) – Dj, anilite
(Cu7S4) – A, copper sulde (CuS2) – S). PA was treated with K2S5O6 solution of dierent concentra-
tion for 4 h at 10 °C. Sulfurized PA was treated with Cu(II / I) salt solution at 80 °C for 10 min. The
concentration of K2S5O6 solution, mol · dm–3: 1 – 0.025; 2 – 0.05; 3 – 0.10; 4 – 0.20
Vitalijus Janickis, Remigijus Ivanauskas, Rūta Stokienė, Mindaugas Andrulevičius
50
us, the established regularities
enable formation on PA surface of
CuxS layers of a desirable composi-
tion and conductivity.
X-ray studies have also shown
that if the sulfurization time of PA is
prolonged, the concentration of the
low-conductive chalcocite (Cu1,96S)
and djurleite (Cu1,9375S) phases de-
creases, but of the more conductive
anilite and rhombohedral digenite
(Cu9S5) increases. If the duration
of PA sulfuration is increased to
four hours (but the concentration
of K2S5O6 solution and tempera-
ture are unchanged), the phase of
the more conductive orthorhombic
anilite (Cu7S4) prevail dominates in
the CuxS layer formed; besides, the
phase of rhombohedral digenite
(Cu9S5) is formed.us, the stoi-
chiometrical composition of copper
sulfides changes in the direction of x
decrease, resulting in the formation
of CuxS layers with a very low elec-
trical resistance.
e study of the phase composi-
tion of CuxS layers by the method of
X-ray photoelectron spectroscopy
(XPS) was restricted to studying the
chemical and phase composition of
the CuxS surface layer.
By the XPS method were studied
copper sulfide layers formed on PA 6
films, which had been sulfurized for
different time (0.5, 4.0 and 6.0 h) in
acidified K2S5O6 solutions of differ-
ent concentration (0.025, 0.05, 0.10
and 0.20 mol · dm–3) and temperature
(1, 10 and 20 °C). en the sulfurized
films were treated for 10 min with a
Cu(II / I) salt solution at a tempera-
ture of 78 °C. e results are shown
in Figs. 8–11 and presented in Ta-
bles 2–4.
e values of Cu 2p3/2 spectra
bond energies of not etched CuxS
layers, presented in Figs. 8 and 9,
indi cate the presence of CuO, Cu2O,
CuS, Cu2S, Cu and CuSO4 in the com-
position of these layers. It is also
obvious that the composition of
these compounds does not depend
on the conditions of sulfurization.
Fig. 7. X-ray diraction patterns of CuxS layers on PA (peaks of djurleite (Cu1.9375S) – Dj, chalcocite (Cu1.96S) – Ch,
anilite (Cu7S4) – A, digenite (Cu9S5) – D, copper sulphide (CuS2) – S). PA had been initially treated with
0.1 mol dm–3 K2S5O6 solution for 4 h at dierent temperature. S ulfurized PA was treated with Cu(II / I) salt
solution at 80 °C for 10 min. The temperature of K2S5O6 solution, °C: 1 – 1; 2 – 10; 3 – 20
Fig. 8. XPS Cu 2p3/2 spectra of unetched copper sulde layers on PA 6 lms formed by their sulfurization for 4 h
in 0.1 mol · dm–3 acidied K2S5O6 solutions of dierent temperature and then treated with Cu(II / I) salt solution
51
Formation and study of electrically conductive layers of copper sulfides formed on the polyamide surface...
Fig. 9. XPS Cu 2p3/2 spec tra of unetched cop per
sulde layers on PA 6 lms, formed by their
sulfurization for 4 h at a temperature of 10 °C
with acidied K2S5O6 solutions of dierent
concentration and then treated with Cu(II / I)
salt solution
Fig. 10. XPS S 2p spectra of unetched copper
sulde layers on PA 6 lms, formed by their
sulfurization for 4 h in 0.1 mol · dm–3 acidied
K2S5O6 solutions of dierent temperature and
then treated with the Cu(II / I) salt solution
Fig. 11. XPS S 2p spectra of unetched copper
sulde layers on PA 6 lms, formed by their
sulfurization for 4 h in K2S5O6 solutions of dif-
ferent concentration at a temperature of 10 °C
and then treated with Cu(II / I) salt solution
Vitalijus Janickis, Remigijus Ivanauskas, Rūta Stokienė, Mindaugas Andrulevičius
52
Table 2. Data of XPS analysis of CuxS layers on PA 6 lms formed by their
sulfurization in acidied 0.1 mol · dm–3 K2S5O6 solution for 4 h at dierent
temperature and then treated with Cu(II / I) salt solution
Sulfuri-
zation
tempe-
rature
Etching
conditions
Ele-
ment
Content,
at %
Atomic
Cu : S
ratio
Electrical sheet
resistance of the
layer, k /
1
Before
etch-
ing
Cu 1.6
1.33
56.13
S 1.2
O 19.1
C 78.1
Etched
for 30 s
Cu 3.8
1.15
S 3.3
O 26.9
C 66.1
Etched
for 90 s
Cu 9.2
1.74
S 5.3
O 13.3
C 72.1
10
Before
etch-
ing
Cu 1.8
0.69
1.12
S 2.6
O 24.4
C 71.1
Etched
for 30 s
Cu 6.3
1.02
S 6.2
O 16.3
C 71.3
Etched
for 90 s
Cu 8.9
1.16
S 7.7
O 19.7
C 63.7
20
Before
etch-
ing
Cu 1.3
1.44
0.13
S 0.9
O 20.7
C 77.0
Etched
for 30 s
Cu 2.8
1.65
S 1.7
O 21.2
C 74.3
Etched
for 90 s
Cu 4.1
1.32
S 3.1
O 14.0
C 78.7
From the S 2p spectra of the same layers one can see that,
besides CuS and CuSO4, also K2SO4 and elemental sulfur are
present in the composition of the layer. Sulfate ions and el-
emental sulfur form during the interaction of sulfurized PA
films with the copper salt solution [40]:
SnO6
2– + 2Cu+ + 2H2O Cu2S + (n-3) S + 2H2SO4.
K2SO4 and sulfur are found in the spectra of copper
sulfides on the surface of PA 6 films, formed by its sulfuriza-
tion at a temperature of 1 and 10 °C. It is possible that not all
CuSO4, K2SO4 and elemental sulfur had been removed from
the surface of copper sulfides layers during their washing
with distilled water aer treatment with a copper salt solu-
tion. It is also impossible to prevent the formation of CuO
and Cu2O in the polymer surface since all processes of cop-
per sulfide layer formation proceed in an oxygen-containing
environment.
From dat a on Cu, S , O an d C di str ibu tion in c opp er su lfid e
layers it follows that the biggest part of the unetched surface
is taken by carbon and oxygen, their content, depending on
sulfurization conditions, changing within 69.2–81.1 at. %
for C and 16.0–25.9 at. % for O. e bulk of carbon must
be attributed to the matrix of the polymer and some part to
gases containing carbon adsorbed on the surface from the
atmosphere. Oxygen is present in the composition of copper
oxides and salts mentioned above (Figs. 8–11) possibly be-
cause of the physical adsorbtion of water and oxides present
in the air.
After a copper sulfide layer had been etched by Ar+
ions during 90 s, the content of carbon remained similar
(62.3–87.1 at. %), but the content of oxygen decreased
(6.8–19.7 at. %), indicating that the bulk of carbon belongs
to the polymer matrix, whereas the content of oxygen in
the deeper layers decreases and does not influence much
the composition of these layers. This was confirmed by
results of X-ray diffraction, since no copper oxides were
detected in the composition of copper sulfide layers. The
content of copper and sulfur on the surface of CuxS lay-
ers, depending on the conditions of sulfurization, changed
within 0.9–2.1 at. % and 0.8–2.6 at. %, respectively. The
concentrations of these elements in the layers after etch-
ing with Ar+ ions for 90 s increased to 2.3–12.9 at. % and
2.4–9.9 at. %, respectively. This indicates a higher concent-
ration of copper sulfides in the layers as compared with
that on the layer surface. The values of the Cu : S atomic
ratio, depending on the sulfurization conditions, changed,
on the surface of the layers and after their etching from
0.69 to 1.93.
Summarising the results obtained by the XPS method,
we may state that copper sulfide layers form on PA 6 film
surface when films are sulfurized in different conditions
and then treated with a Cu(II / I) salt solution. The follow-
ing compounds were detected on the surface of the lay-
ers: CuO, Cu2O, Cu S, C u2S, Cu, CuSO4, K2SO4 and elemental
sulfur. It is known that the value of x in CuxS sulfides may
change from 1 to 2, forming non-stoichiometric sulfides.
But XPS analysis according to the literature data and the
values of bonding energies give a possibility to determine
only stoichiometric sulfides (CuS and Cu2S). Thus, an XPS
study gives only additional information concerning the
composition of copper sulfide layers formed on PA 6 film
surface. More comprehensive data were obtained by X-ray
diffraction analysis of CuxS layers formed by us, as shown
above.
53
Formation and study of electrically conductive layers of copper sulfides formed on the polyamide surface...
Table 3. Data of XPS analysis of CuxS layers on PA 6 lms, formed by their
sulfurization in acidied K2S5O6 solution of dierent concentration for 4 h
at a temperature of 10 °C and then treated with Cu(II / I) salt solution
The concent-
ration of sulfuri-
zation solution,
mol · dm–3
Etching
condi tions
Ele-
ment
Content,
at %
Atomic
Cu : S
ratio
Electrical
sheet resis-
tance of the
layer, k /
0.025
Before
etching
Cu 0.9
0.69
6.56
S 1.3
O 19.8
C 78.0
Etched
for 30 s
Cu 2.3
1.28
S 1.8
O 20.3
C 75.6
Etched
for 90 s
Cu 4.3
1.79
S 2.4
O 10.5
C 82.8
Etched
for 180 s
Cu 7.2
1.53
S 4.7
O 14.8
C 73.3
0.05
Before
etching
Cu 1.6
1.23
2.67
S 1.3
O 17.3
C 79.8
Etched
for 30 s
Cu 7.1
1.15
S 6.2
O 14.4
C 72.3
Etched
for 90 s
Cu 12.9
1.30
S 9.9
O 14.8
C 62.3
0.1
Before
etching
Cu 1.8
0.69
1.12
S 2.6
O 24.4
C 71.1
Etched
for 30 s
Cu 6.3
1.02
S 6.2
O 16.3
C 71.3
Etched
for 90 s
Cu 8.9
1.16
S 7.7
O 19.7
C 63.7
0.2
Before
etching
Cu 1.0
1.25
0.39
S 0.8
O 17.1
C 81.1
Etched
for 30 s
Cu 1.9
1.19
S 1.6
O 34.5
C 62.0
Etched
for 90 s
Cu 4.9
1.40
S 3.5
O 12.0
C 79.6
Table 4. Data of XPS analysis of CuxS layers on PA 6 lms, formed by their
sulfurization in acidied 0.1 mol · dm–3 K2S5O6 solution at a temperature of
20 °C for dierent periods of time and then treated with Cu(II / I) salt solution
The duration
of sulfuriza-
tion, h
Etching
condi-
tions
Ele-
ment
Content,
at %
Atomic
Cu : S
ratio
Electrical
sheet resis-
tance of the
layer, k /
0.5
Before
etch-
ing
Cu 2.1
0.75 450.0
S 2.8
O 25.9
C 69.2
4.0
Before
etch-
ing
Cu 1.3
1.44
0.127
S 0.9
O 20.7
C 77.0
Etched
for
30 s
Cu 2.8
1.65
S 1.7
O 21.2
C 74.3
Etched
for
90 s
Cu 4.1
1.32
S 3.1
O 14.0
C 78.7
6.0
Before
etch-
ing
Cu 1.5
1.25
0.104
S 1.2
O 16.0
C 81.2
Etched
for
30 s
Cu 4.1
1.78
S 2.3
O 9.6
C 84.0
Etched
for
90 s
Cu 2.3
1.32
S 3.8
O 6.8
C 87.1
Etched
for
180 s
Cu 5.5
0. 85
S 6.5
O 12.5
C 75.5
CONCLUSIONS
1. e sorption of pentathionate ions from acidified
0.025–0.20 mol · dm–3 water solutions of potassium penta-
thionate, K2S5O6, by polyamide 6 films has been studied by
IR (400–1300 cm–1), UV (200–400 nm) absorption spectra
and chemical methods. Peaks in the IR spectra of pentathion-
ate anions sorbed into a polyamide were found in the inter-
vals 418–484, 523–568, 609–737, 985–1079, 1111–1284 cm–1
and assigned to the νS–S, δas(O–S–O), δs(O–S–O), νs(S–O)
and νas(S–O), respectively. ree absorption maxima were
observed in the UV absorption spectra: at 250 nm as a clear
shoulder, at 285 nm as a peak, and at 325 nm as an unclearly
defined shoulder. ese spectral data have confirmed that sul-
fur is sorbed by PA films in the form of pentathionate ions.
Vitalijus Janickis, Remigijus Ivanauskas, Rūta Stokienė, Mindaugas Andrulevičius
54
2. e concentration of sulfur sorbed by a polymer in-
creases with increasing the temperature, the concentration
of the potassium pentathionate solution and the duration of
polymer treatment.
e concentration of copper in a polymer film is strongly
dependent on the concentration of sulfur in the PA, i. e. the
amount of copper varies in proportion to sulfur concentra-
tion in the samples.
3. Copper sulfide, CuxS, layers on the surface of polyamide,
formed by the use of potassium pentathionate as a precursor
of a polymer chalcogenization, were studied by the methods
of chemical analysis, X-ray diffraction and by atomic force
microscopy. X-ray diffraction studies of CuxS layers revealed
five phases: djurleite (Cu1.9375S), chalcocite (Cu1.96S), anilite
(Cu7S4), digenite (Cu9S5) and copper sulphide (CuS2). e
phase composition depended on the conditions of PA sulfur-
ization and the subsequent treatment of the sulfurized poly-
mer with a Cu(II / I) salt solution.
4. e formation regularities of CuxS layers and the
chemical and phase composition of the formed layers enable
obtaining electrically conductive or semi-conductive copper
sulfide films. e sheet resistance of the samples varied from
104 / to 1.52 M / and depended on the conditions
of PA interaction with K2S5O6 solution. e obtained results
and the established regularities enable formation on polya-
mide film surface of CuxS layers of a desirable composition
and conductivity.
5. e X-ray photoelectron spectroscopic determination
of the chemical composition of CuxS layers up to 1 nm deep
confirmed formation of copper sulfides of various phases in
the surface of a polyamide.
Received 12 December 2008
Accepted 29 December 2008
References
1. S. T. Lakshmikumar, Mater. Sol. Cells, 32, 7 (1994).
2. V. M. Garcia, P. K. Nair, M. T. Nair, J. Cryst. Growth,
203(1–2), 113 (1999).
3. R. S. Mane, C. D. Lokhande, Mater. Chem. Phys., 65, 1
(2000).
4. X.-H. Liao, N.-Y. Chen, S. Xu, S.-B. Yang, J. Zhu, J. Cryst.
Growth, 252, 593 (2003).
5. R. N. Bhattacharya, H. Wiesner, T. A. Berens, R. J. Matson,
J. Keane, R. K. Ramanathan, A. Swartzlander, A. Mason,
R. Nou, J. Electrochem. Soc., 4, 1376 (1997).
6. J. Cardoso, O. Gomezdaza, L. Ixthilco, M. T. S. Nair,
P. K. Nair, Semicond. Sci. Technol., 16, 123 (2001).
7. A. Žebrauskas, A. Mikalauskienė, Chemistry, 3, 84 (1993).
8. Pat. USSR 1331291 (1986).
9. Pat. USSR 268525 (1986).
10. J. Johansson, J. Kostamo, M. Karppinen, L. Niinistö, J.
Mater. Chem., 12, 1022 (2002).
11. G. E. Zaikov, A. L. Yordanskiy, V. S. Markin, Diusion of
Electrolytes into the Polymers, Moscow (1984).
12. O. Foss, in: H. J. Emeleus, A. G. Sharpe (eds.), Advances
in Inorganic Chemistry and Radiochemistry, New York,
Academic Press, 2, 237 (1960).
13. K. Mar oy, Crystal structures of penta-, selenopenta-, tel-
luropenta- and hexathionates, PhD thesis, Bergen, Norway
(1975).
14. V. J. Janickis, S. A. Grevys, Rus. J. Inorg. Chem., 22, 411
(1977).
15. R. Maciulevičius, Formation of copper sulde layers on
polyamide using polythionic acids, PhD thesis, Kaunas,
Lithuania (1995).
16. Pat. 4402 B, Lithuania (1998).
17. V. Janickis, R. Maciulevičius, R. Ivanauskas, I. Ancutienė,
Coll. Polym. Sci., 281, 84 (2003).
18. R. Maciulevičius, V. Janickis, R. Ivanauskas, Chemistry 4,
141 (2000).
19. J. Janickis, J. Valančiūnas, V. Zelionkaitė, V. Janickis,
S. Grevys, Trans. Lithuanian Acad. Sci. Ser. B, 3(88), 83
(1975).
20. S. Grevys, V. Janickis, Chem. Technol., 2(36), 95 (2005).
21. R. Ivanauskas, V. Janickis, R. Maciulevičius, Chem. Technol.,
4(13), 71 (1999).
22. R. Ivanauskas, R. Stokienė, V. Janickis, N. Kreivėnienė,
Chem. Technol., 1(35), 20 (2005).
23. V. Janickis, R. Ivanauskas, R. Stokienė, N. Kreivėnienė,
Chem. Technol., 3(37), 32 (2005).
24. V. Janickis, R. Ivanauskas, R. Stokienė, Chem. Techno l.,
3(39), 29 (2006).
25. I. Ancutienė, V. Janickis, R. Ivanauskas, R. Stokienė,
N. Kreivėnienė, Polish J. Chem., 81, 381 (2007).
26. A. Kurtenacker, W. Fluss, Z. Allgem. Anorg. Chemie, 210,
125 (1933).
27. P. K. Norkus, G. S. Šimkevičiūtė, Rus. J. Analyt. Chem., 26,
39 (1971).
28. I. Ancutienė, V. Janickis, V. Grevys, Chemistry, 2, 3 (1997).
29. Analytical Methods for Atomic Absorption Spectrometry,
Perkin–Elmer Corp., Norwalk, Conn. (1973).
30. D. Briggs, in: M. P. Seach (ed.), Surface Analysis by Auger and
X-ray Pho to electron Spectroscopy, Mir, Moscow (1987).
31. C. D. Wagner, W. M. Riggs, L. E. Davis, J. F. Moulder et al.,
Handbook of X-ray Photoelectron Spectroscopy, Perkin–
Elmer Corp., Minnesota (1978).
32. V. J. Janickis, J. V. Janickis, Trans. Lithuanian Acad. Sci. Ser.
B, 6(157), 43 (1986).
33. L. Lorenz, R. Samuel, Z. Physik. Chem. (B), 14, 219 (1931).
34. M. Schmidt, T. Sand, J. Inorg. Nucl. Chem., 26, 1173 (1964).
35. K. Koto, N. Morimoto, Acta Crystallogr. Sec. B, 26, 915
(1970).
36. Jr. Howard, Science, 203, 356 (1979).
37. Jr. H. E. King, C. T. Prewitt, Am. Mineral., 64, 1265
(1979).
38. A. Janosi, Acta Crystallogr., 17, 311 (1964).
39. A. Žebrauskas, Chem. Technol., 1(3), 39 (1996).
40. V. Janickis, Chem. Technol., 4(30), 5 (2003).
55
Formation and study of electrically conductive layers of copper sulfides formed on the polyamide surface...
Vitalijus Janickis, Remigijus Ivanauskas, Rūta Stokienė,
Mindaugas Andrulevičius
ELEKTRAI LAIDŽIŲ VARIO SULFIDŲ SLUOKSNIŲ
POLIAMIDO PAVIRŠIUJE SUDARYMAS NAUDOJANT
KALIO PENTATIONATĄ IR JŲ TYRIMAS
Santrauka
Puslaidininkiniai ir elektrai laidūs vario sulfidų sluoksniai sudaryti
poliamido 6 (PA) paviršiuje sorbciniu-difuziniu metodu, naudojant
vandeninį kalio pentationato, K2S5O6, tirpalą, kaip polimero sieri-
nimo prekursorių. Pentationato jonai, turintys dvivalenčių mažo
oksidacijos laipsnio sieros atomų grandinę O3S–S–S–S–SO3
,
yra sorbuojami–įdifunduoja į PA plėveles, jeigu jos apdorojamos
K2S5O6 tirpalu. Sorbuotos sieros koncentracija didėja, didinant pre-
kursoriaus tirpalo koncentraciją, temperatūrą ir PA apdorojimo
trukmę. CuxS sluoksniai susidaro PA plėvelių paviršiuje, kai sierin-
tas polimeras apdorojamas vandeniniu vario(II / I) druskų tirpalu:
pentationato anijonai reaguoja su vario jonais. Vario koncentracija
didėja (iki 40 mg · g–1), didėjant prekursoriaus tirpalo koncentraci-
jai ir temperatūrai.
Rentgeno difrakcinės analizės rezultatai patvirtino CuxS
sluoks nių susidarymą PA paviršiuje. Fazinė CuxS sluoksnio sudėtis
pri klauso nuo kalio pentationato tirpalo koncentracijos ir tempe-
ratūros bei nuo pradinio apdorojimo K2S5O6 tirpale trukmės. Šie
sluoksniai sudaryti iš mažai laidaus tetragoninio chalkocito, Cu1.96S,
monoclinio djurleito, Cu1.9375S, elektrai laidaus romboedrinio di-
genito, Cu9S5, ortorombinio anilito, Cu7S4, ir kubinio CuS2. Fazinė
sudėtis lemia elektrines sudarytų sluoksnių savybes: elektrinė kva-
drato varža kinta nuo 0,104 iki 1,52 · 103 K / . Sluoksnių sudė-
ties nustatymas rentgeno fotoelektroninės spektroskopijos metodu
patvirtino įvairių fazių vario sulfidų susidarymą. Nustatyti dėsnin-
gumai įgalina sudaryti PA paviršiuje norimos sudėties ir laidumo
elektrai CuxS sluoksnius.
... By this method the surface of a polymer film is initially treated by the solution containing sulfurization agent and then by the aqueous solution of metal salt. Sodium polysulfides [11], polythionic acids and polythionates [12,13], thiourea [14 -16], and sulfur in carbon disulfide solution [17] have already been used for sulfurization of polymer foils by different methods. The sulfurization process using cited agents is prolonged, many of them are quite harmful, and sometimes their preparation is complicated. ...
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The processes of formation of electrically conductive layers of copper sulfides Cu x S by the sorption–diffusion method on polypropylene (PP) using molten sulfur as sulfurizing agent was investigated. The amount of sorbed sulfur increased with the increase of the duration of treatment. Copper sulfide layers were formed on the surface of polypropylene after the treatment of sulfurized polymer with Cu(II/I) salt solution. The amount of copper sulfide in layer increased with the increase of treatment duration in copper salt solution. XRD spectra of PP films treated for 3 min with molten sulfur and then with Cu(II/I) salt solution for the different time showed that the copper sulfide phases, mostly digenite, Cu 2-x S and α-chalcocite, Cu 2 S were formed in the layers. Electromotive force measurement results confirmed the composition of formed Cu x S layers on PP. The phase composition of layers also changed after the annealing. The value of electrical resistance of copper sulfide layers on PP varied from 20 Ω/cm 2 to 80 Ω/cm 2 and after annealing at 80 °C – in the interval of 10 Ω/cm 2 – 60 Ω/cm 2 .
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The ability of sulfur to form chains is displayed in the allotropes of the element and in a variety of compounds built up of sulfur chains terminated by other atoms or groups. The maximum number of sulfur atoms in the chain of compounds so far isolated and characterized varies with the nature of the end groups; in some it is four or six and in others reaches eight. The major structural problem with regard to sulfur chain compounds originates in their tendency to give off sulfur when acted upon by bases or sulfur acceptors like sulfite or cyanide. The problems concerning reactivity are closely connected, and the mechanisms by which desulfurations and shortenings of chains take place. At present, there is convirlcing evidence, chemical as well as physical, that in compounds containing chains of sulfur atoms, the chains are unbranched. Indeed, branching has not been found in any instance. This review is concerned with the physical evidence, particularly from structure determinations by X-ray methods; the chemical side is mentioned but only leading references are given.
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Copper-indium-gallium-selenium (Cu-In-Ga-Se) precursor thin films have been prepared by electrodeposition techniques on molybdenum substrates. The films have been characterized by inductively coupled plasma spectrometry, Auger electron spectroscopy, x-ray diffraction, electron probe microanalysis, current-voltage characteristics, spectral response, and electron-beam-induced current. Additional In or Cu, Ga, and Se have been added to the electrodeposited precursor film by physical evaporation to adjust the final composition to Culn 1-xGa xSe 2, and allowed to crystallize at 550°C. A ZnO/CdS/CuIn 1-xGa xSe 2 device fabricated using electrodeposited Cu-In-Ga-Se precursor layers resulted in an efficiency of 12.3%.
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