Electrodeposition of antimony from chloride-free ethylene glycol solutions and fabrication of thermoelectric Bi2Te3/(Bi1-xSbx)2Te3 multilayers using pulsed potential electrodeposition

Article abstract of DOI:10.1016/j.electacta.2014.08.111

The electrochemical behavior of antimony in chloride-free ethylene glycol and the electrodeposition of antimony-bismuth and antimony-tellurium binary alloys, and bismuth-antimony-tellurium ternary alloys from ethylene glycol solutions were investigated by means of cyclic voltammetry (CV), electrochemical quartz crystal microbalance (EQCM) and rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) experiments. It was found that antimony(III), tellurium(IV) and bismuth(III) have comparable diffusion coefficients in ethylene glycol. The electrodeposition potential of antimony was more negative than that of tellurium and the alloy deposition obeyed regular alloy deposition behavior. In the ternary alloy deposition experiments, only a bismuth-telluride alloy could be electrodeposited at low overpotentials and the antimony content in the alloy increased when more negative potentials were applied or when lower rotation speeds were used. Bi₂Te₃/(Bi_1-xSb_x)₂Te₃ multilayers were obtained by alternating the electrodeposition potentials using a rotating disk electrode. During the deposition of antimony by reduction of antimony(III) in ethylene glycol, explosive antimony was probably formed.

Full text of DOI:10.1016/j.electacta.2014.08.111

Electrochimica Acta 147 (2014) 451–459
Contents lists available at ScienceDirect
Electrochimica Acta
journal homepage: www.elsevier.com/locate/electacta
Electrodeposition of antimony from chloride-free ethylene glycol
solutions and fabrication of thermoelectric Bi Te /(Bi Sb ) Te
multilayers using pulsed potential electrodeposition
2
3
1−x
x 2
3
a
b
a,∗
Minxian Wu , Koen Binnemans , Jan Fransaer
a
KU Leuven, Department of Materials Engineering, Kasteelpark Arenberg 44 P.O. box 2450, B-3001 Leuven, Belgium
KU Leuven, Department of Chemistry, Celestijnenlaan 200F P.O. box 2404, B-3001 Leuven, Belgium
b
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 15 June 2014
Received in revised form 25 August 2014
Accepted 25 August 2014
The electrochemical behavior of antimony in chloride-free ethylene glycol and the electrodeposition
of antimony-bismuth and antimony-tellurium binary alloys, and bismuth-antimony-tellurium ternary
alloys from ethylene glycol solutions were investigated by means of cyclic voltammetry (CV), electro-
chemical quartz crystal microbalance (EQCM) and rotating disk electrode (RDE) and rotating ring-disk
electrode (RRDE) experiments. It was found that antimony(III), tellurium(IV) and bismuth(III) have com-
parable diffusion coefficients in ethylene glycol. The electrodeposition potential of antimony was more
negative than that of tellurium and the alloy deposition obeyed regular alloy deposition behavior. In the
ternary alloy deposition experiments, only a bismuth-telluride alloy could be electrodeposited at low
overpotentials and the antimony content in the alloy increased when more negative potentials were
applied or when lower rotation speeds were used. Bi2Te3/(Bi1−xSbx)2Te3 multilayers were obtained by
alternating the electrodeposition potentials using a rotating disk electrode. During the deposition of
antimony by reduction of antimony(III) in ethylene glycol, “explosive” antimony was probably formed.
Keywords:
Electrodeposition
Thermoelectric
Ethylene glycol
Multilayer
MSC:
0
9
0-01
9-00
©
2014 Elsevier Ltd. All rights reserved.
1
. Introduction
can be significantly enhanced through nanostructuring [15,16].
Multilayer (superlattice) thermoelectric materials are one of the
nanostructuring materials that have larger ZT values than bulk
materials [17]. Multilayer thermoelectric materials utilize the mis-
match between two different layers leading to phonon scattering
which reduces the thermal conductivity. Venkatasubramanian et al.
reported a ZT value of about 2.4 for p-type Bi Te /Sb Te superlat-
Thermoelectric materials are attracting a lot of interest in recent
years [1–5]. They can be used as power generator by converting a
temperature difference into electricity (Seebeck effect). They can
also use electricity current to generate a heat flux (Peltier effect).
The direction of the heat flux depends on the direction of the electric
current. They can transfer heat against a thermal gradient. But the
number of applications of thermoelectric materials is still limited
due to the low conversion efficiencies [5–7]. The conversion effi-
ciency of a thermoelectric materials can be evaluated using a figure
2
3
2
3
tices at 300 K [18]. Thermoelectric materials can be obtained by
electrochemical deposition which is an easy and fast technique
[19–23]. Several research groups made efforts to electrodeposit
bismuth-telluride-based mutilayer thermoelectric material. Ma
et al. electrodeposited Bi Te /Sb Te multilayer from two aqueous
2
of merit, ZT = ˛ ꢀT/k, where ˛ is the Seebeck coefficient, ꢀ is the
2
3
2
3
electric conductivity, k is the thermal conductivity and T is the
absolute temperature. Bismuth telluride and the derived antimony-
and selenium-doped compounds have the highest ZT number
plating baths [24]. The electrodeposition of Bi Te /(Bi
Sbx) Te3
2
3
1−x 2
multilayers from a single aqueous bath was studied by Banga et al.
[25]. Bi Te Se/Te and Bi Te /(Bi0.3Sb ) Te multilayer nanowire
2
2
2
3
0.7 2
3
(
ꢀ1) at room temperature of all known thermoelectric materi-
arrays were synthesized by pulsed potential deposition [26,27].
Ethylene glycol was found to be an excellent solvent for
electrodeposition of bismuth telluride [28,29]. Equilibrium alloy
deposition was obtained in ethylene glycol solutions with dissolved
nitrate salts, and the film composition could be easily controlled by
adjusting the molar ratio of bismuth(III) and tellurium(IV) in the
solution. Due to the high solubility of both bismuth(III) and tel-
lurium(IV) compounds in ethylene glycol, current densities up to
als [5,8–13]. However, thermoelectric devices must have a ZT > 3
to become competitive with large-scale conventional cooling and
power generation devices [14]. The thermoelectric performance
∗ Corresponding author.
E-mail address: jan.fransaer@mtm.kuleuven.be (J. Fransaer).
http://dx.doi.org/10.1016/j.electacta.2014.08.111
0
013-4686/© 2014 Elsevier Ltd. All rights reserved.

4
52
M. Wu et al. / Electrochimica Acta 147 (2014) 451–459
−
2
−
5.0 A dm could be obtained. Antimony can be electrodeposited
rotating disk electrode experiments were performed on a platinum
rotating disk (ꢁ = 3 mm, Autolab).
The electrochemistry of antimony in ethylene glycol solutions
was studied using an electrochemical quartz crystal microbalance
(EQCM, Maxtek). The mass change per unit area (ꢂm) was deter-
mined from the Sauerbrey equation: [43]
from various kinds of electrolytes [30–38]. In the aqueous solu-
tions, Sb O is a commonly used antimony source. It dissolves as
2
3
+
antimonyl SbO in very acidic media (−2 < pH < 1). In the pH range
between 2 and 10, it forms undissociated HSbO which is virtu-
2
ally insoluble. In more alkaline solutions, Sb O dissolves upon
2
3
−
formation of the antimonite ion SbO2 [39,40]. To get hydrolyzed
antimony ions for electrodeposition, very acidic or alkaline solu-
tions were used in the literature for electrodeposition of antimony.
Electrodeposited antimony is chemically attacked in very acidic
ꢂf = −C ꢂm
(1)
f
where ꢁf is the frequency change and C is the sensitivity factor
f
−1
2
of the crystal, which was calibrated as 4020 Hz g m in ethylene
glycol solutions for a 5 MHz AT cut quartz crystal with a diameter
of 2.54 cm. The working electrode was Pt/Ti with a surface area of
media. Qiu et al. used an alkaline solution to dissolve Sb O to
2
3
deposit antimony [41]. However, the addition of a diaminourea
polymer was required to obtain smooth and uniform films. SbCl3
has a high solubility in ethylene glycol. Yamamoto et al. dissolved
2
1.37 cm . The calibration process followed the method described by
Gabrielli et al. [44]. A solution of 50 mM AgNO in ethylene glycol
3
8
.1 mol.% SbCl (∼1.58 M) in ethylene glycol to study the electrode-
3
was used for calibration, and depositions were done at constant
potentials. The sensitivity factor was calculated using the Sauerbrey
equation by assuming the current efficiency for silver deposition in
this solution is 100%.
position of antimony from ethylene glycol [42].
In our experiments, ethylene glycol was used as the solvent.
In order to have better control of film composition, smooth film
morphology and to be sure that the solution is less corrosive,
chloride-free solutions were prepared and used. In this paper,
we describe the electrochemical behavior of the electrodeposi-
tion of antimony, antimony-bismuth and bismuth-tellurium alloys.
All the electrochemical experiments were carried out with an
EG&G 273 potentiostat/galvanostat or an Autolab PGSTAT 302N
potentiostat. The elemental compositions of the deposited films
were determined by inductively coupled plasma optical emis-
sion spectroscopy (ICP-OES, Varian 720-ES apparatus). The water
contents of the solutions were measured using a Mettler-Toledo
DL39 Karl Fischer coulometer. The films were characterized by
scanning electron microscopy (SEM, Philips XL 30 FEG) using
secondary electrons (SE) and back-scattered electrons (BSE). The
antimony distribution in the multilayer was analyzed by wave-
length dispersive–electron probe microanalyzer (WD-EPMA, field
emission microprobe JXA-8530F). X-ray diffraction (XRD, Seifert
3003) was used to characterize the crystal structure of the deposits.
Thermoelectric Bi Te /(Bi Sbx) Te multilayers were electrode-
posited from a single bath using pulsed potential deposition.
2
3
1−x
2
3
2
. Experimental
Ethylene glycol (Alfa Aesar, 99%), SbCl3 (Alfa Aesar, >99%),
TeCl4 (Alfa Aesar, >99%), Bi(NO ) ·5H O (Alfa Aesar, >98%),
3 3
2
AgNO (Sigma-Aldrich, >99%), ferrocene (Acros Organics, 98%), fer-
3
rocenium hexafluorophosphate (Sigma-Aldrich, 97%) and LiNO3
(
Sigma-Aldrich, 99%) were used as received. Sb(NO3)3 solutions
3
. Results and discussion
in ethylene glycol were prepared by mixing equal volumes of a
solution of 0.4 M SbCl3 in ethylene glycol and a solution of 1.2 M
AgNO (a slight excess) in ethylene glycol, followed by removal of
3.1. Electrodeposition of antimony in ethylene glycol
3
the AgCl precipitate by centrifugation. The excess of silver(I) ions
was removed by electrodeposition of silver on a large surface area
platinum mesh working electrode, by applying a constant poten-
tial of −0.1 V (vs. Ag) and a platinum coil as the counter electrode.
Te(NO ) solutions were prepared according to a literature pro-
cedure [29]. After pre-electrolysis, the 0.2 M Sb(NO3)3 and 0.5 M
Te(NO3)4 ethylene glycol solutions were found to have a resid-
ual silver content of 4 ppm and 6 ppm, respectively (determined
by ICP-OES on a Varian 720-ES apparatus).
The cyclic voltammograms of a solution of 50 mM Sb(NO ) and
3
3
0
.5 M LiNO in ethylene glycol on a platinum working electrode are
3
shown in Fig. 1a. The CVs were stopped at different cathodic vertex
potentials to study the reduction reactions at different potentials.
There are two reduction waves on the cathodic scan. The first reduc-
tion wave r1 is at +0.12 V, and the main reduction peak r2 at −0.08 V
is assigned to the bulk reduction of Sb(III) ions to elemental anti-
mony. The reduction potential of antimony in ethylene glycol is
3
4
more negative than that in the acidic solutions (E0
= +0.21 V
+
SbO /Sb
All the experiments were carried out in a three-electrode set-up
on a lab bench. Ethylene glycol is hydrophilic and it absorbs water
from the environment, so all the solutions used contained 3–5%
of water. The reference electrode was a glass tube with a porous
ceramic plug in the bottom filled with an ethylene glycol solution
with equimolar (2 mM) ferrocene (Fc) and ferrocenium hexaflu-
vs. SHE), but more positive than its reduction potential in alka-
line solutions (E0
= −0.66 V vs. SHE) [45]. On the reverse
−
SbO /Sb
2
scan, a distinct stripping peak a1 was observed at a potential more
positive to the onset of the bulk stripping peak a2. However, on
the glassy carbon working electrode, only one reduction peak and
one oxidation peak could be observed which illustrates the effect
of substrate property on the pre-wave (Fig. 1b). A similar pre-
wave was observed during the deposition of antimony from the
dimethyl sulfoxide (DMSO) solution containing 20 mM SbCl3 by
Li and co-workers [46]. They claimed that the pre-peak was due
to the reduction of Sb(III) to Sb(II) and Sb(II) was further reduced
to elemental antimony at more negative potentials. However, the
pre-wave r1 in ethylene glycol solutions could not be assigned to
Sb(III) to Sb(II). This was proven by the wait-scan experiments: a
constant potential of +0.1 V, where only the first reduction reac-
tion would happen, was applied for 10 seconds, then the potential
scanned from +0.1 V to +1.1 V after waiting at open circuit poten-
tial for different times. An oxidation peak was always observed
at the potential scan, indicating the reduction product at the first
reduction peak was insoluble and did not diffuse away during the
+
+
orophosphate (Fc ) and 1 M LiNO . The potential of the Fc/Fc
3
electrode was compared with the Ag/AgCl/3 M KCl electrode in a
+
3
M KCl solution at room temperature. The potential of Fc/Fc elec-
trode was +0.29 V vs. Ag/AgCl/3 M KCl electrode. In this paper, all
the potentials were converted with respect to the standard hydro-
gen electrode (SHE). A platinum coil was used as counter electrode.
The films were deposited on gold-coated silicon wafers (silicon cov-
ered with 500 nm of silica, 10 nm of titanium and 100 nm of gold).
The wafers were cleaned by degreasing in an alkaline cleaner (P3-
◦
RST Henkel) at 70 C for 10 min, then rinsed with deionized water
and immersed in a 10 wt.% HCl solution for 1 min, followed by rins-
ing with deionized water and absolute ethanol, and finally dried
in a stream of warm air. The working electrode for cyclic voltam-
metry and for linear scan voltammetry experiments was a polished
®
platinum disk (diameter ꢁ = 1 mm) embedded in EpoFix resin. The

M. Wu et al. / Electrochimica Acta 147 (2014) 451–459
453
(a) 1.2
Pt
0
0
0
0
.9
.6
.3
.0
a2
a1
r1
-
0.3
0.6
r2
-
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
E / V vs. SHE
Fig. 2. SEM images of the antimony films deposited from a 50 mM Sb(NO3)3 and
0.5 M LiNO3 solution in ethylene glycol at 50 C at different potentials: (a) +0.1 V, (b)
◦
(b) 0.6
−
0.05 V, and (c) −0.15 V.
GC
0
0
.3
.0
the crystalline form. The stripping peak a1 associated with the
pre-wave r1 was observed before the oxidation peak a2 which cor-
responds to the dissolution of bulk antimony. The pre-wave can be
assigned to the deposition of amorphous antimony.
Very uniform and flat antimony films could be electrodeposited
at +0.1 V. At more negative potentials, the film became rough and
dendrites could be observed (Fig. 2). Electrochemical quartz crys-
tal microbalance (EQCM) studies were carried out to compare the
electrochemical behavior of antimony deposition in a solution of
Sb(NO3)3 in ethylene glycol with the behavior of a solution of
-
0.3
0.6
SbCl in ethylene glycol. Cyclic voltammograms were recorded on
3
-
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
a platinum-coated EQCM working electrode, and the correspond-
ing frequency was simultaneously recorded using an EQCM. Fig. 3
shows the EQCM results of the ethylene glycol solution of Sb(NO3)3
Fig. 1. Cyclic voltammograms of an ethylene glycol solution containing 0.05 M
Sb(NO3)3 and 0.5 M LiNO3 at 50 C on different working electrodes: (a) on a plat-
inum disk electrode: the CVs were stopped at different cathodic vertex potentials,
and (b) on a glassy carbon disk electrode. The counter electrode was a platinum coil.
The scan rate was 20 mV s
◦
or SbCl . The blue curves are the real mass changes on the crystal
3
which are calculated based on the frequency changes, and the red
curves are the theoretical mass changes which are based on the
charge passed through the working electrode. The mass increased
during the cathodic scan due to the deposition of antimony, and
then the mass decreased as the current changed to positive which
is due to the stripping of the deposit from the crystal. In the ethylene
glycol solution containing Sb(NO ) (Fig. 3a), the theoretical mass
−
1
.
waiting time. Rotating ring-disk electrode (RRDE) experiment also
shows that there was no Sb(II) produced on the cathodic scan. A
constant potential of +0.8 V (vs. SHE) was applied on the ring while
a cyclic voltammetry was performed on the disk. No oxidation cur-
rent was detected on the ring. This suggests that no Sb(II) or Sb(I)
ions formed on the disk. Besides, to the best of our knowledge, there
are no other literature reports on the existence of Sb(II) species in
solution. So the pre-wave r1 is not due to the multi-step reduc-
tion of Sb(III). The nucleation loop on the cyclic voltammogram and
the position of the pre-oxidation peak eliminates the possibility of
the underpotential deposition of antimony [47,48]. A reasonable
explanation for this pre-wave is the formation of the “explosive”
allotrope of antimony. “Explosive” antimony is an amorphous,
metastable form of antimony. By providing excitation energy, for
instance by rubbing or scratching the compound, it “explosively”
transforms into the stable crystalline form [49,50]. Preparation of
3
3
did not fall back to zero after cyclic voltammetry. This is because
the cathodic charge was greater than the anodic charge leading to
a current efficiency lower than 100%. This is also evident in the
EQCM data where it can be seen that the real mass increase dur-
ing the cathodic scan is lower than the theoretical mass increase. In
the potential range of the first reduction wave (Fig. 3a inset), a mass
increase could be observed, indicating antimony was deposited on
the working electrode. This finding is consistent with the statement
in the previous paragraph that Sb(III) is not reduced to Sb(II). In the
SbCl -containing ethylene glycol solution (Fig. 3b), on the forward
3
scan, the real mass of the antimony deposit coincided with the the-
oretical mass change at potentials more positive than −0.4 V (vs.
SHE). At the potentials more negative than −0.4 V, the experimen-
tally observed mass became greater than the theoretical one. This
can be explained by the morphology effect. At more negative over-
potentials, the films became very rough and feather-like dendrites
were formed leading to a mass increase (Fig. 4). At the first reduc-
tion peak (Fig. 3b inset), a real mass increase was also observed,
which is due to the deposition of antimony. In both Sb(NO ) and
“
explosive” antimony by electrodeposition was first described by
Gore in 1855 [51]. This kind of amorphous antimony can be easily
obtained by continuous electrodeposition from aqueous solutions
at room temperature or below room temperature [50,52]. The crys-
tallinity can be improved by elevating the temperature, increasing
the deposition rate or using pulsed electrodeposition [53–55]. In
ethylene glycol solutions, the peak current density of the pre-wave
r1 is only −0.05 A dm which is a favorable condition for forming
amorphous antimony. The electrodeposited amorphous antimony
is less stable than crystalline antimony, so that it is stripped before
3
3
SbCl solutions, a pre-wave could be observed which corresponds
3
−
2
to the deposition of amorphous antimony.
The diffusion coefficient of Sb(III) in the ethylene glycol solu-
tion containing 0.05 M Sb(NO ) and 0.5 M LiNO was studied using
3
3
3

4
54
M. Wu et al. / Electrochimica Acta 147 (2014) 451–459
(
a) 0.8
120
90
(a)
0
.0
theoretical
0
0
0
0
.6
.4
.2
.0
real
60
-0.3
1
00 rpm
50 rpm
200 rpm
00 rpm
30
1
-0.6
-0.9
-1.2
0
3
-0.2
-0.4
-0.6
-30
-60
-90
500 rpm
800 rpm
-0.9 -0.6 -0.3 0.0
0.3
0.6
0.9
1.2
1.5
-0.6
-0.4
-0.2
0.0
0.2
0.4
E
/ V vs. SHE
E
/ V vs. SHE
(
b) 1.2
240
180
120
60
(b)
1
0
0
0
0
.2
0
0
0
0
.9
real
.6
.3
.0
theoretical
.9
.6
.3
.0
0
-
-
-
0.3
0.6
0.9
-60
-120
-180
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
E
/ V vs. SHE
0
2
4
6
1 1/2
8
10
-
(
/ rad s )
Fig. 3. Cyclic voltammograms and corresponding real mass and theoretical mass
changes on the crystal in ethylene glycol solutions containing (a) 50 mM Sb(NO3)3
◦
Fig. 5. Polarization curves performed on an antimony-coated platinum rotating disk
(ꢁ = 3 mm) in an ethylene glycol solution containing 50 mM Sb(NO ) and 0.5 M
and 0.5 M LiNO3, and (b) 50 mM SbCl3 and 0.5 M LiNO3 at 50 C. The working and
−
1
counter electrodes were platinum, and the scan rate was 20 mV s
.
3 3
◦
LiNO3 at 50 C (a), and Levich plot (b). The counter electrode was a platinum coil,
−
1
and the scan rate was 5 mV s
.
scans with different rotating speeds were carried out on a plat-
inum rotating disk electrode, and all the scans started from open
circuit potential. Fig. 5a shows the polarization curves without IR-
drop correction. The limiting current density at each rotation speed
could be easily read from the plateau. The currents at −0.27 V were
taken as the limiting currents. The diffusion coefficient of Sb(III)
ions was derived from the plot of the limiting current density
and the square root of the rotation speed (Fig. 5b), and a value of
−
11
2
−1
6
.96 ± 0.34 10
m s (95% confidence interval) was obtained.
−
9
2
−1
This value is smaller than that in aqueous solutions (∼10 m s ),
but of the same order as the value in the choline chloride - urea deep
−
11
2
−1
eutectic solvent (1.76 10
m s ) [57]. The difference in diffusion
coefficient in different solutions is due to the variation in viscosity.
As the Stoke-Einstein equation illustrates, the diffusion coefficient
is inversely proportional to viscosity. The viscosity of ethylene gly-
col is higher than water leading to a lower diffusion coefficient in
ethylene glycol. The value of the diffusion coefficient of Sb(III) ions
is comparable to the values of the diffusion coefficients of Bi(III)
and Te(IV) ions in the chloride-free ethylene glycol solutions, 8.5
Fig. 4. SEM image of the antimony film deposited from a 50 mM SbCl3 and 0.5 M
LiNO3 solution in ethylene glycol at 50 C at −0.15 V.
◦
linear scan voltammetry on a rotating disk electrode. The diffusion
coefficient in the solution was calculated from the Levich equation
−
11
2
−1
−11 −1
2
1
0
m s and 3.2 10
m s , respectively [29].
[
56]:
2
3
1
2
1
6
−
3.2. Electrodeposition of Sb-Te and Bi–Sb alloys
jl = 0.62z FD
ω
ꢃ
c
(2)
−
2
where j is the limiting current density (A m ), F is the Faraday
The cyclic voltammogram of a solution of 50 mM Sb(NO ) and
l
3 3
−1
2
−1
s ), c
constant (96485 C mol ), ꢃ is the kinematic viscosity (m
is the concentration (mol m ), and ω is the rotation rate (rad s ).
Based on the linear relationship between ω and j , the diffusion
coefficient can be calculated from the slope. A series of cathodic
50 mM Bi(NO3)3 in ethylene glycol contains two reduction peaks
(Fig. 6a). Because bismuth and antimony are perfectly miscible in
the solid state, there is only one stripping peak. The first reduction
peak at +0.14 V can be assigned to the reduction of Bi(III) to Bi(0).
−
3
−1
√
l

M. Wu et al. / Electrochimica Acta 147 (2014) 451–459
455
(
a) 2.0
(a)
-14
1
1
0
0
.5
.0
.5
.0
-
-
-
-
-
15
16
17
18
19
Bi + Sb
Bi
Sb
-
0.5
1.0
-
0.0
0.2
0.4
0.6
0.8
1.0
-0.5
0.0
0.5
1.0
1.5
XSb
E
/ V vs. SHE
(b)
(
b) 2.5
0
0
0
0
0
.25
.20
.15
.10
.05
Sb + Te
2
1
1
0
0
.0
.5
.0
.5
.0
Sb
Te
-0.5
0
.0
0.2
0.4
0.6
0.8
1.0
-
1.0
XSb
-
0.5
0.0
0.5
1.0
1.5
E
/ V vs. SHE
Fig. 7. Gibbs free energy of bismuth-antimony alloys (a) and the calculated potential
shift of antimony versus the mole fraction of antimony (b), calculated at 50 C.
◦
◦
Fig. 6. Cyclic voltammograms in ethylene glycol solutions at 50 C: (a) 50 mM
Sb(NO3)3, 50 mM Bi(NO3)3 and 0.5 M LiNO3, (b) 50 mM Sb(NO3)3, 50 mM Te(NO3)4
and 0.5 M LiNO3. The working and counter electrodes were platinum, and the scan
xSb is the molar fraction of antimony in the alloy. The deposition
potential shift of antimony in bismuth-antimony alloy deposition
was calculated according to the free energy of bismuth-antimony
alloy, as shown in Fig. 7. The Gibbs free energy is proportional to the
alloy composition, and the deposition potential of antimony shifted
−
1
rate was 20 mV s
.
The second reduction peak at +0.015 V is due to the formation of a
bismuth-antimony alloy. This peak lies at a potential +0.09 V more
positive than the potential of the reduction of pure antimony (Fig. 1)
which is caused by the activity of the alloy constituents [58,59]:
+
0.051 V to more positive potential. The potential shift calculated
from equation 6 and 7 corresponds well with the experimental shift
of the potential observed in Fig. 6a.
ꢀ
ꢁ
ꢀ
ꢁ
RT
aSb3+
RT
4F
aBi3+
0
Sb
0
Bi
E
+
ln
+ ÁSb = E
+
ln
+ ÁBi
(3)
(4)
(5)
3F
aSb
ꢁ
aBi
Bismuth-antimony alloys were electrodeposited from ethylene
ꢀ
glycol solution containing 50 mM Sb(NO ) and 50 mM Bi(NO ) at
ꢄ
3 3
3 3
Sb
aSb = exp
different potentials. The SEM images of the films are shown in Fig. 8.
At large overpotentials, nucleation is favored over crystal growth
and the crystals become smaller. The antimony content in the alloy
increased as more negative potentials were applied.
RT
ꢂ
ꢃ
RT
F
ꢄSb
0
ESb = E
Sb
+
ln aSb3+
−
+ ÁSb
3
3F
0
i
z+
where E is the standard potential, a is the activity of discharged
ions, a is the activity of the metal at the surface of the alloy, Á
is the cathodic overpotential, and ꢄ is the chemical potential or
partial molar free energy of component i in the alloy. If the charge
transfer kinetics for the deposition of component i is independent
Fig. 6b shows the cyclic voltammogram of a solution of 50 mM
Sb(NO3)3 and 50 mM Te(NO3)4 in ethylene glycol. There are two
reduction peaks on the cathodic scan. The first peak at around
+0.14 V is due to the reduction of Te(IV) to Te(0), and the second
peak at +0.02 V is due to the formation of an antimony-tellurium
alloy. This peak lies at a potential +0.1 V more positive than the
potential of the reduction of pure antimony (Fig. 1) due to the alloy
formation lowering the chemical potential of antimony in the alloy.
The antimony-tellurium alloy electrodeposition in ethylene glycol
follows the regular deposition behavior. The electrodeposition of
the more noble element, tellurium, in the ethylene glycol solu-
tion containing both Te(NO3)4 and Sb(NO3)3 is favored at lower
overpotentials. The tellurium content in the film increases as its
molar ratio increases in the bath (Fig. 9). Very uniform and flat
antimony-tellurium films were obtained from +0.18 V to −0.04 V,
i
i
i
i
of the substrate composition, then Á is constant. The deposition
potential shift of antimony in alloy deposition can then be written
i
as:
ꢄSb
ꢂESb = − 3F
(6)
(7)
Gꢁ
∂
ꢁ
ꢄSb = G + (1 − xSb
)
∂
xSb
ꢁ
where G is the Gibbs free energy of the alloy, which was calculated
using the thermodynamic simulation software PANDATTM, where

4
56
M. Wu et al. / Electrochimica Acta 147 (2014) 451–459
Fig. 8. SEM images of the bismuth-antimony films deposited from
Sb(NO3)3, 50 mM Bi(NO3)3 and 0.5 M LiNO3 solution in ethylene glycol at 50 C at
a
50 mM
Fig. 10. SEM images of the antimony telluride films deposited from a 50 mM
Sb(NO3)3, 50 mM Te(NO3)4 and 0.5 M LiNO3 solution in ethylene glycol at 50 C at
◦
◦
different potentials: (a) +0.18 V (99 at.% Bi), (b) +0.08 V (86 at.% Bi), and (c) −0.04 V
different potentials: (a) 0.18 V (95 at.% Te), (b) 0.08 V (74 at.% Te), and (c) −0.04 V
(
64 at.% Bi).
(64 at.% Te).
1
00
1
00
5
1
2
5
0 rpm
00 rpm
00 rpm
00 rpm
8
6
4
2
0
0
0
0
0
8
6
0
0
0
0
0
.18 V
.08 V
V
40
20
0
-0.1 V
0
20
40
60
80
100
-0.2
-0.1
0.0
0.1
0.2
0.3
Te in bath / (at.%)
E
/ V vs. SHE
Fig. 9. Dependence of the film composition on the electrolyte bath composition at
◦
4+
3+
5
0
C without stirring. The total metal ion concentration ([Te ]+[Sb ]) was 0.2 M.
Fig. 11. Composition of the films electrodeposited from an ethylene glycol solution
containing 20 mM Bi(NO3)3, 100 mM Sb(NO3)3, 30 mM Te(NO3)4 and 0.5 M LiNO3 at
◦
50
C on a rotating disk electrode with different rotating speeds: red: 50 rpm, blue:
and the atomic concentration of tellurium in the film decreased at
more negative potentials in an ethylene glycol solution containing
100 rpm, green: 200 rpm and grey: 500 rpm. The symbols represent the concentra-
tion of different elements: • Bi, ꢀ Sb, and ꢁ Te.
5
0 mM Te(NO ) and 50 mM Sb(NO ) (Fig. 10).
3 4 3 3
4
. Electrodeposition of multilayered thermoelectric
material
To obtain thermoelectric material with a high ZT number, a high
electric conductivity and a low thermal conductivity are desired.
The most common way to increase ZT number is reducing the ther-
mal conductivity by increasing phonon scattering more than the
electron scattering. One way to achieve that is by making multilayer
materials. The scattering of phonons at the interphase of the two
layers lowers the thermal conductivity of the material. Multilayer
materials are expected to have better thermoelectric performance
compared to the single layer materials. Bi Te /(Bi
Sbx) Te mul-
2
3
1−x
2 3
tilayer material could be electrodeposited from a single bath using
pulse plating with the help of a rotating disk electrode. In the solu-
tion containing 20 mM Bi(NO ) , 100 mM Sb(NO ) and 30 mM
3
3
3 3
Te(NO ) , films with different compositions were electrodeposited
3
4
(
Fig. 11). The antimony content in the film increased and the
Fig. 12. SEM pictures of the films electrodeposited from an ethylene glycol solution
containing 20 mM Bi(NO3)3, 100 mM Sb(NO3)3 and 30 mM Te(NO3)4 at −0.1 V with
tellurium content decreased as more negative potentials were
applied. The increase in antimony content accompanied a decrease
of tellurium content. This phenomenon was also observed for
different rotation speeds: (a) 50 rpm, (b) 100 rpm, (c) 200 rpm, and (d) 500 rpm at
◦
50
C.

M. Wu et al. / Electrochimica Acta 147 (2014) 451–459
457
(
Bi Sb ) Te
1-x x 2 3
x=0.64
x=0.17
x=0.12
x=0.09
∗
x=0
2
0
25
30
35
40
45
50
55
o
2
/
Fig. 14. XRD patterns of the (Bi1−xSbx)2Te3 films electrodeposited from an ethylene
glycol solution containing 20 mM Bi(NO3)3, 100 mM Sb(NO3)3, 30 mM Te(NO3)4 and
◦ ∗
.5 M LiNO3 at 50 C. The pattern is reported in ref. [29].
0
electrodeposition from aqueous solutions [25]. At more positive
potentials or higher rotation speeds, 60 at.% Te could be obtained.
At rotation speeds of 100 rpm and 200 rpm, the tellurium con-
tent increased from 40 at.% to 60 at.% for all potentials and the
antimony fraction x in Bi1 Sbx decreased from 0.38 to 0.10. At a
−x
rotation rate of 500 rpm, the tellurium content was about 60 at.%
at all the potentials, and the antimony fraction x varied from 0.24
to 0.10. The morphology of the films changed with the rotation
speed and applied potentials. Fig. 12 and 13 are SEM images of films
electrodeposited at different rotation speeds and different poten-
tials. With an increase in the rotation speeds, the crystals became
larger. The crystals became smaller when more negative potentials
were applied. The surface images of the films electrodeposited from
the ethylene glycol solution exhibited a smooth morphology. The
cross-section of the film (Fig. 13e) shows a continuous film instead
of crystal islands. The Seebeck coefficient of the electrodeposited
Fig. 13. SEM pictures of films electrodeposited from an ethylene glycol solution
containing 20 mM Bi(NO3)3, 100 mM Sb(NO3)3 and 30 mM Te(NO3)4 with a rotation
speed of 200 rpm at different potentials: (a,e) +0.25 V, (b) +0.1 V, (c) 0.0 V, (d) and
◦
−
0.1 V at 50 C. (a-d) shows the surface morphology of the films and (e) shows the
cross-section.
(
Bi1 Sbx) Te3 films were measured using the method described
−x 2
Fig. 15. BSE images (a,b) and antimony distribution (c) of films electrodeposited from an ethylene glycol solution containing 20 mM Bi(NO3)3, 100 mM Sb(NO3)3, 30 mM
◦
Te(NO3)4 and 0.5 M LiNO3 at 50 C and for different rotation rates: (a) 500 rpm, the potential was switched from −0.1 V for 60 s to +0.25 V for 200 s (b) 200 rpm, the potential
was switched from −0.1 V for 80 s to +0.25 V for 500 s.

4
58
M. Wu et al. / Electrochimica Acta 147 (2014) 451–459
by Nguyen et al. [60]. (Bi1 Sbx) Te (x < 0.4) thin films are n-type
thermoelectric materials.
References
−x
2
3
[
[
1] J.R. Sootsman, D.Y. Chung, M.G. Kanatzidis, New and old concepts in thermo-
electric materials, Angew. Chem. Int. Ed. 48 (2009) 8616–8639.
2] M. Zebarjadi, K. Esfarjani, M.S. Dresselhaus, Z.F. Ren, G. Chen, Perspectives on
thermoelectrics: from fundamentals to device applications, Energy Environ.
Sci. 5 (2012) 5147–5162.
The alloys containing 60 at.% Te were electrodeposited at dif-
ferent conditions. The X-ray diffraction (XRD) patterns of those
(
Bi1 Sbx) Te illustrate the existence of a single rhombohedral
−x 2 3
phase (Fig. 14). The diffraction peaks shift to higher angles with
the increase of antimony content. Similar peak shifts were also
[
3] Y. Pei, H. Wang, G.J. Snyder, Band engineering of thermoelectric materials, Adv.
Mater. 24 (2012) 6125–6135.
found for bulk (Bi1 Sbx) Te materials synthesized by mechanical
−x
2
3
[4] A. Shakouri, Recent developments in semiconductor thermoelectric physics
and materials, Annu. Rev. Mater. Res. 41 (2011) 399–431.
[5] L.E. Bell, Cooling, heating, generating power, and recovering waste heat with
thermoelectric systems, Science 321 (2008) 1457–1461.
◦
alloying and pulse discharge sintering [61]. The peak at 2Â ∼ 27.8 ,
◦
◦
◦
3
5
8.3 , 41.2 and 50.3 correspond to the crystal orientation of (0 1
), (1 0 10), (1 1 0) and (2 0 5), respectively.
[
6] Z.-G. Chen, G. Han, L. Yang, L. Cheng, J. Zou, Nanostructured thermoelectric
materials: Current research and future challenge, Prog. Nat. Sci. 22 (2012)
(
Bi0.91Sb ) Te /(Bi0.8Sb ) Te multilayer films were elec-
0.09 2 3 0.2 2 3
535–549.
trodeposited from the ethylene glycol solution containing 20 mM
Bi(NO ) , 100 mM Sb(NO ) and 30 mM Te(NO3)4 on a rotating
[
7] D.A. Polvani, J.F. Meng, N.V. Chandra Shekar, J. Sharp, J.V. Badding,
Large improvement in thermoelectric properties in pressure-tuned p-type
Sb1.5Bi0.5Te3, Chemistry of Materials 13 (2001) 2068–2071.
3
3
3 3
disk electrode with a rotation speed of 500 rpm. Pulsed potential
deposition was used to obtain layers with different composi-
tions. (Bi0.8Sb ) Te layers were electrodeposited at −0.1 V and
[
[
8] D.M. Rowe (Ed.), CRC Handbook of Thermoelectrics, CRC, Boca Raton (Fla.),
1995.
0.2 2
3
9] W. Liu, K.C. Lukas, K. McEnaney, S. Lee, Q. Zhang, C.P. Opeil, G. Chen, Z. Ren,
Studies on the Bi Te -Bi Se -Bi S system for mid-temperature thermoelectric
(
Bi0.91Sb ) Te layers were electrodeposited at +0.25 V. The layer
0.09 2 3
2
3
2
3
2 3
energy conversion, Energy Environ. Sci. 6 (2013) 552–560.
thickness could be easily controlled using different pulsed time. The
back scatter electrons image (BSE) of the cross-section in Fig. 15a
shows a clear contrast between each layer, indicating the differ-
ent layer compositions. The antimony distribution is shown in
Fig. 15c. Each layer has a thickness around 1 ␮m. There is almost
no antimony present in the layer electrodeposited at +0.25 V. The
fraction of antimony in the alloy could be increased by reducing
[
[
10] B.C. Sales, Smaller is cooler, Science 295 (2002) 1248–1249.
11] B. Poudel, Q. Hao, Y. Ma, Y. Lan, A. Minnich, B. Yu, X. Yan, D. Wang, A. Muto, D.
Vashaee, X. Chen, J. Liu, M.S. Dresselhaus, G. Chen, Z. Ren, High-thermoelectric
performance of nanostructured bismuth antimony telluride bulk alloys, Science
320 (2008) 634–638.
[
[
12] A. Purkayastha, A. Jain, C. Hapenciuc, R. Buckley, B. Singh, C. Karthik, R.J. Mehta,
T. Borca-Tasciuc, G. Ramanath, Synthesis and thermoelectric properties of thin
film assemblies of bismuth telluride nanopolyhedra, Chem. Mater. 23 (2011)
3029–3031.
the rotation speed. (Bi0.9Sb ) Te /(Bi0.7Sb
)
Te2.2 multilayers
0.1 2
3
0.3 2.8
13] Y. Ma, E. Ahlberg, Y. Sun, B.B. Iversen, A.E. Palmqvist, Thermoelectric properties
of thin films of bismuth telluride electrochemically deposited on stainless steel
substrates, Electrochim. Acta 56 (2011) 4216–4223.
were electrodeposited at a rotation speed of 200 rpm using a poten-
tial of −0.1 V for 80 s and +0.25 V for 500 s (Fig. 15b). The layer
thickness could be easily controlled by adjusting the deposition
time. Efforts were made to measure both the in-plane and cross-
plane thermal conductivity. However due to the influence of the
substrates, the errors were so large that the results were not
reliable.
[
[
14] C.B. Vining, An inconvenient truth about thermoelectrics, Nat. Mater. 8 (2009)
83–85.
15] C. Frantz, N. Stein, Y. Zhang, E. Bouzy, O. Picht, M. Toimil-Molares, C. Boulanger,
Electrodeposition of bismuth telluride nanowires with controlled composition
in polycarbonate membranes, Electrochim. Acta 69 (2012) 30–37.
16] I.Y. Erdogan, Ümit Demir, Orientation-controlled synthesis and characteriza-
tion of Bi2Te3 nanofilms, and nanowires via electrochemical co-deposition,
Electrochim. Acta 56 (2011) 2385–2393.
[
[
[
17] L. Hicks, M. Dresselhaus, Effect of quantum-well stuctures on the thermoelec-
tric figue of merit, Phys. Rev. B 47 (1993) 12727–12731.
18] R. Venkatasubramanian, E. Siivola, T. Colpitts, B. O’Quinn, Thin-film thermo-
electric devices with high room-temperature figures of merit, Nature 413
5
. Conclusions
Chloride-free ethylene glycol solutions were used for electrode-
(
2001) 597–602.
position of antimony and Bi Te /(Bi Sbx) Te multilayers. In the
2
3
1−x
2
3
[19] W. Glatz, L. Durrer, E. Schwyter, C. Hierold, Novel mixed method for the electro-
chemical deposition of thick layers of Bi2+xTe3−x with controlled stoichiometry,
Electrochim. Acta 54 (2008) 755–762.
antimony solutions, Sb(III) was reduced to two different allotropes.
Amorphous antimony might have been obtained at the first reduc-
tion wave in the cyclic voltammogram. At more negative potentials,
Sb(III) was reduced to crystalline Sb(0). Both bismuth-antimony
and antimony-tellurium show regular alloy deposition behavior
from chloride-free ethylene glycol solutions. The antimony con-
tent in the alloys increased at more negative potentials. In the alloy
deposition, the formation of the alloys lowered the partial molar
energy of antimony leading to a positive shift of reduction potential
[
20] B. Yoo, C.-K. Huang, J. Lim, J. Herman, M. Ryan, J.-P. Fleurial, N. Myung, Elec-
trochemically deposited thermoelectric n-type Bi2Te3 thin films, Electrochim.
Acta 50 (2005) 4371–4377.
21] H. Köse, M. Bicer, C. Tutunoglu, A.O. Aydin, I. Sisman, The underpotential depo-
sition of Bi2Tey−3Sey thin films by an electrochemical co-deposition method,
Electrochim. Acta 54 (2009) 1680–1686.
[
[22] F.-H. Li, W. Wang, Electrodeposition of p-type Bi Sb Tey thermoelectric film
x
2−x
from dimethyl sulfoxide solution, Electrochim. Acta 55 (2010) 5000–5005.
[
23] W.-J. Li, W.-L. Yu, C.-Y. Yen, Pulsed electrodeposition of Bi2Te3 and Bi2Te3/Te
nanowire arrays from
510–515.
a DMSO solution, Electrochim. Acta 58 (2011)
of antimony. n-Type thermoelectric Bi Te /(Bi Sbx) Te (x < 0.4)
2
3
1−x
2
3
multilayer could electrodeposited from a single electroplating bath
by pulsed potentials using a rotating disk electrode. The layer
thickness could be controlled by changing the deposition time.
Lowering the rotation speed or electrodepositing at higher over-
potential increased the antimony fraction in the (Bi1 Sbx) Te3
ternary alloys.
[24] Y. Ma, E. Ahlberg, Y. Sun, B.B. Iversen, A.E.C. Palmqvist, Thermoelectric char-
acteristics of electrochemically deposited Bi2Te3 and Sb2Te3 thin films of
relevance to multilayer preparation, J. Electrochem. Soc. 159 (2012) D50–D58.
[
25] D. Banga, J.L. Lensch-Falk, D.L. Medlin, V. Stavila, N.Y.C. Yang, D.B. Robinson, P.A.
Sharma, Periodic modulation of Sb stoichiometry in Bi2Te3/Bi2−xSbxTe3 multi-
layers using pulsed electrodeposition, Cryst. Growth Des. 12 (2012) 1347–1353.
26] X. Li, K. Cai, D. Yu, Y. Wang, Electrodeposition and characterization of thermo-
electric Bi2Te2Se/Te multilayer nanowire arrays, Superlattices Microstruct. 50
−x
2
[
(
2011) 557–562.
[
[
27] B. Yoo, F. Xiao, K.N. Bozhilov, J. Herman, M.A. Ryan, N.V. Myung, Electrodeposi-
tion of thermoelectric superlattice nanowires, Adv. Mater. 19 (2007) 296–299.
28] H.P. Nguyen, M. Wu, J. Su, R.J. Vullers, P.M. Vereecken, J. Fransaer, Electrodepo-
sition of bismuth telluride thermoelectric films from a nonaqueous electrolyte
using ethylene glycol, Electrochim. Acta 68 (2012) 9–17.
29] M. Wu, H.P. Nguyen, R.J. Vullers, P.M. Vereecken, K. Binnemans, J. Fransaer,
Electrodeposition of bismuth telluride thermoelectric films from chloride-free
ethylene glycol solutions, J. Electrochem. Soc. 4 (2013) D196–D201.
Acknowledgements
The authors acknowledge financial support from the IWT (SBO
project “Material processing in ionic liquids”, MAPIL) and the
FWO-Flanders (Research community “Ionic liquids”, and research
project G.0B96.13N). The authors thank Ruud Vullers from the
Holst institute for the gold sputtered wafers. The authors also
[
[
30] Y.N. Sadana, J.P. Singh, R. Kumar, Electrodeposition of antimony and antimony
alloys-A review, Surf. Coat. Technol. 24 (1985) 319–353.
thank Yuanyuan Guan and Liugang Chen for their help with
[31] J. Kuleshova, E. Koukharenko, X. Li, N. Frety, I.S. Nandhakumar, J. Tudor,
S.P. Beeby, N.M. White, Optimization of the electrodeposition process of
high-performance bismuth antimony telluride compounds for thermoelectric
applications, Langmuir 26 (2010) 16980–16985.
TM
PANDAT
tively.
software and field emission microprobe, respec-

M. Wu et al. / Electrochimica Acta 147 (2014) 451–459
459
[
32] H.P. Nguyen, X. Peng, G. Murugan, R.J.M. Vullers, P.M. Vereecken, J. Fransaer,
Electrodeposition of antimony, tellurium and their alloys from molten
acetamide mixtures, J. Electrochem. Soc. 160 (2013) D75–D79.
[48] Y.-C. Fu, J.-W. Yan, Y. Wang, J.-H. Tian, H.-M. Zhang, Z.-X. Xie, B.-W.
Mao, In situ STM studies on the underpotential deposition of antimony on
Au(111) and Au(100) in a BMIBF4 ionic liquid, J. Phys. Chem. C 111 (2007)
10467–10477.
[49] C. Wickersham, G. Bajor, J. Greene, Impulse stimulated “explosive” crystalliza-
tion of sputter deposited amorphous (In,Ga)Sb films, Solid State Commun. 27
(1978) 17–20.
[50] F. Aymerich, A. Delunas, On the explosive semiconductor-semimetal transition
of antimony, Phys. Stat. Sol (a) 31 (1975) 165–170.
[51] G. Gore, On a peculiar phenomenon in the electro-deposition of antimony,
Philos. Mag. 9 (1855) 73–74.
[52] C. Coffin, Studies on explosive antimony. ii. its structure, electrical conductivity,
and rate of crystallization, Proc. Roy. Soc A 152 (1935) 47–63.
[53] J. Lensch-Falk, D. Banga, P. Hopkins, D. Robinson, V. Stavila, P. Sharma, D. Medlin,
Electrodeposition and characterization of nano-crystalline antimony telluride
thin films, Thin Solid Films 520 (2012) 6109–6117.
[
[
33] I.K. Gisbert Leimkühler, R. Reineke-Koch, Electrodeposition of antimony tel-
luride, J. Electrochem. Soc. 149 (2002) C474–C478.
34] M.-H. Yang, M.-C. Yang, I.-W. Sun, Electrodeposition of indium antimonide from
the water-stable 1-ethyl-3-methylimidazolium chloride/tetrafluoroborate
ionic liquid, J. Electrochem. Soc. 150 (2003) C544–C548.
[
[
35] Q. Huang, A.J. Kellock, S. Raoux, Electrodeposition of sbte phase-change alloys,
J. Electrochem. Soc. 155 (2008) D104–D109.
36] X. Dou, G. Li, H. Lei, X. Huang, L. Li, I.W. Boyd, Template epitaxial growth of
thermoelectric Bi/BiSb superlattice nanowires by charge-controlled pulse, J.
Electrochem. Soc. 156 (2009) K149–K154.
[
37] M. Martín-González, A.L. Prieto, M.S. Knox, R. Gronsky, T. Sands, A.M. Stacy,
Electrodeposition of Bi1−xSbx films and 200-nm wire arrays from a nonaqueous
solvent, Chem. Mater. 15 (2003) 1671–1681.
[
[
[
38] H. Ebe, M. Ueda, T. Ohtsuka, Electrodeposition of Sb, Bi, Te, and their alloys in
AlCl3-NaCl-KCl molten salt, Electrochim. Acta 53 (2007) 100–105.
39] M. Pourbaix, Atlas of electrochemical equilibria in aqueous solutions, NACE
International, Houston Texas USA, 1974.
40] A.L. Pitman, M. Pourbaix, N. de Zoubov, Potential-pH diagram of the antimony-
water system: Its applications to properties of the metal, its compounds, its
corrosion, and antimony electrodes, J. Electrochem. Soc. 104 (1957) 594–600.
41] W. Qiu, S. Yang, T. Zhu, J. Xie, X. Zhao, Antimony telluride thin films electrode-
posited in an alkaline electrolyte, J. Electron. Mater. 40 (2011) 1506–1511.
42] H. Yamamoto, R. Iguchi, M. Morishita, Electrodeposition of Zn-Sb alloy film
from ethylene glycol solvent, ECS Trans 16 (2009) 191–201.
[54] H. Jung, N.V. Myung, Electrodeposition of antimony telluride thin films from
acidic nitrate-tartrate baths, Electrochim. Acta 56 (2011) 5611–5615.
[55] M.-Y. Kim, T.-S. Oh, Crystallization behavior and thermoelectric characteris-
tics of the electrodeposited Sb2Te3 thin films, Thin Solid Films 518 (2010)
6550–6553.
[56] S. Treimer, A consideration of the application of Koutecky-Levich plots in the
diagnoses of charge-transfer mechanisms at rotated disk electrodes, Electro-
analysis 14 (2002) 154–171.
[57] F. Golgovici, A. Cokocaru, M. Nedelcu, T. Visan, Voltammetric and impedance
studies of electrodeposition of Te and its binary compounds with Bi and Sb
using choline chloride- urea based electrolyte, Chalcogenide Lett. 6 (2009)
323–333.
[58] R.C. Alkire, D.M. Kolb, Chemistry - Advances In Electrochemical Science And
Engineering, Vol. 7, Wiley-VCH, Weinheim, 2002.
[
[
[
[
[
[
[
43] G. Sauerbrey, Verwendung von Schwingquarzen zur Wägung dünner Schichten
und zur Mikrowägung, Z. Phys. 155 (1959) 206–222.
44] C. Gabrielli, M. Keddam, R. Torresi, Calibration of the electrochemical quartz
crystal microbalance, J. Electrochem. Soc. 138 (1991) 2657–2660.
45] A.J. Bard, R. Parsons, J. Jordan, Standard potentials in aqueous solutions, CRC
Press, New York, 1985.
46] F. Li, W. Wang, Y. Gong, J. Li, Electrodeposition of SbxTey thermoelectric films
from dimethyl sulfoxide solution, J. Electron. Mater. 41 (2012) 3039–3043.
47] C. Wang, Y. Du, Z. Zhou, The study of antimony underpotential deposition
on gold electrode and its analytical application, Electroanalysis 14 (2002)
[59] T. Moffat, Electrodeposition of Ni1−xAlx in a chloroaluminate melt, J. Elec-
trochem. Soc. 141 (1994) 3059–3070.
[60] H. Nguyen, J. Su, Z. Wang, R. Vullers, P.M. Vereecken, J. Fransaer, Measuring
in-plane seebeck coefficicent of electroplated thermoelectric films in presence
of a conductive seed layer, J. Mater. Res 26 (2011) 1953–1957.
[61] X.-D. Liu, Y.-H. Park, Structure and transport properties of (Bi1−xSbx)2Te3 ther-
moelectric materials prepared by mechanical alloying and pulse discharge
sintering, Mater. Trans. 43 (2002) 681–687.
8
49–852.