Supplemental Material
Enhanced Thermoelectric Performance of In-substituted
GeSb6Te10 with Homologous Structure
Atsuko Kosuga,1,a) Kazuki Nakai,1,2 Mie Matsuzawa,1 Yousuke Fujii,1 Ryoji Funahashi,3
Takuya Tachizawa,2 Yoshiki Kubota,2 and Kouichi Kifune2,4
1
Nanoscience and Nanotechnology Research Center, Research Organization for the 21st
Century, Osaka Prefecture University, Sakai 599-8570, Japan
2
Department of Physical Science, Graduate School of Science, Osaka Prefecture
University, Sakai 599-8531, Japan
3
Research Institute for Ubiquitous Energy Devices, National Institute of Advanced
Industrial Science & Technology, Ikeda 563-8577, Japan
4
Faculty of Engineering, Hiroshima Institute of Technology, Hiroshima 731-5193, Japan
*E-mail: a-kosuga@21c.osakafu-u.ac.jp
Figure S1.
TG-DTA profile of GeSb6Te10.
Figure S1 shows that the mass loss up to 750 K was within 0.4%, so we considered the material
chemically stable over several consecutive warming and cooling cycles within the temperature range
of the ZT measurement.
Figure S2.
Le Bail fitting of 0 at.%, 3 at.%, 5 at.% and 10 at.% In-substituted GeSb6Te10 (denoted In-0, In-3,
In-5, and In-10, respectively) using a commensurate model. The dotted and solid lines are the
observed data and fit, respectively. The vertical marks show the Bragg peaks of GeSb6Te10. The
bottom curve is the difference between the observed and calculated patterns. The R factors are
Rwp=13.56%, Rp=9.55% for In-0; Rwp=14.35%, Rp=10.03% for In-3; Rwp=14.54%, Rp=10.2% for
In-5; Rwp=12.26%, Rp=9.12% for In-10.
Table SI.
Room-temperature crystal structure and transport properties of GeInxSb6−xTe10 (x=0, 0.18, 0.3, and
0.6; corresponding to In-0, In-3, In-5, and In-10, respectively).
In-0
In-3
In-5
In-10
Crystal structure
Lattice parameter a3-layer (Å)
4.2492(2)
4.2458(5)
4.2427(5)
4.2407(9)
Lattice parameter c3-layer (Å)
5.9997(3)
5.9846(7)
5.9964(6)
5.993(1)
93.815(6)
93.43(2)
93.48(2)
93.33(4)
1.7642(1)
1.7602(1)
1.76461(9)
1.7613(2)
Lattice volume V3-layer
(Å3)
Modulation wavevector q
Transport properties
Electrical resistivity,  (m)
4.1
5.5
15.7
22.2
(VK−1)
32.7
38.3
74.0
76.8
0.40
0.56
0.59
0.94
27.7
11.1
8.6
3.0
0.9
1.3
2.5
3.6
2.16
1.58
0.93
0.44
Lattice thermal conductivity, lat (Wm−1K−1)
0.3–1.0
0.3-0.8
0.5-0.6
0.1–0.3
Electronic thermal conductivity, el
1.1–1.8
0.8-1.4
0.3-0.5
0.1–0.2
Debye temperature, D (K)
172
–
–
165
Dimensionless figure of merit, ZT
0.04
0.05
0.12
0.19
Seebeck coefficient, S
Carrier concentration, n×1021 (cm−3)
Carrier mobility,
(cm2V−1s−1)
Carrier effective mass, m*
Thermal conductivity,
 (Wm−1K−1)
(Wm−1K−1)
TABLE SII.
Bulk density and relative density of GeInxSb6−xTe10 (x=0, 0.18, 0.3, and 0.6; corresponding to In=0, 3,
5, and 10 at.% substitution, respectively, denoted as In-0, In-3, In-5, and In-10, respectively).
In-0
In-3
In-5
In-10
Bulk density, d (gcm−3)
6.181
6.382
6.315
6.347
Relative density, d/dth×100 (%)
95
98
97
98
The theoretical density (dth) of GeSb6Te10 used to calculate these relative densities is 6.5019
gcm−3, derived from its lattice parameters and the atomic weights of the compound.
Figure S3.
Temperature dependence of  of 0, 3, 5, and 10 at. % In-substituted GeSb6Te10 (In-0, In-3, In-5, and
In-10, respectively).
Figure S4.
Low-temperature Cp data and T3–Cp plot of In-0.