| 학회 |
한국재료학회 |
| 학술대회 |
2018년 가을 (11/07 ~ 11/09, 여수 디오션리조트) |
| 권호 |
24권 2호 |
| 발표분야 |
H. 한-일 재료공학(KJMST 2018) |
| 제목 |
Transport properties of the layered hexagonal compound, EuSn2As2 |
| 초록 |
Thermoelectric exchange (TE) power generators are solid-state devices based on thermoelectric power. TE materials is expected to convert thermal current (or temperature gradients) to electric voltage without a chemical reaction. The efficiency of TE materials is verified by the material-specific dimensionless figure of merit ZT, which is defined as ZT = S2Tρ-1κ-1, where S is the Seebeck coefficient, ρ is the electrical resistivity, κ is the thermal conductivity, and T is the absolute temperature. Although many researchers have searched for new TE materials with higher ZT, one of the most widespread TE materials is still Bismuth telluride (Bi2Te3) and its alloys, which was reported by Goldsmid et al. in 1950s. There are still requirement for a new TE material which exhibits higher ZT than that of Bi2Te3 at room temperature. In this work, we demonstrate the TE properties of layered hexagonal compounds, EuSn2As2. The crystallographic structure of EuSn2As2 consists of isolated Eu2+ cations and [Sn2As2]2-anions bilayers, which is bound by van der Waals forces. Both EuSn2As2 and Bi2Te3 crystal has a hexagonal structure that consists of atomic layer series along the c-axis. And since, both [Sn2As2]2-–[Sn2As2]2- and Te–Te layers are weakly bonded by the van der Waals forces. The measured density of the hot-pressed (HP) polycrystalline EuSn2As2 sample was 6.53(6) g cm-3 and the porosity was 2.4(9) vol.%. The HP sample was defined that directions for the X-ray diffraction (XRD) measurements vertical/parallel to the pressing axis as P⊥/P//. The XRD pattern of P// shows c-axis orientation in hexagonal lattice. ρ was measured by the DC four-terminal method. κ was measured both by the steady-state method (SS-κ) and by the laser flash method (LF-κ). The transport properties of HP EuSn2As2 sample were as follows: ρ= 0.264(16) mΩ cm, S =-43(0) μV K-1, and SS-κ= 8.2(2) W m-1 K-1 in the P⊥ direction at 373(2) K and LF-κ= 5.5(6) W m-1 K-1 at 376 K in the direction of P//. Thus, ZT is equal to 0.032(3) at 373(2) K in the P⊥ direction. The measurements of T dependence of ZT of HP EuSn2As2 will be reported in the conference. |
| 저자 |
Ryosuke SAKAGAMI1, Harunari KARIMATA2, Nobuhiko AZUMA3, Michitaro YAMAGUCHI4, Suguru IWASAKI5, Yosuke GOTO6, Yoshikazu MIZUGUCHI1, Masanori MATOBA2, Yoichi KAMIHARA3
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| 소속 |
11Department of Applied Physics and Physico-Informatics, 2Faculty of Science and Technology, 3Keio Univ., 43-14-1 Hiyoshi, 5Yokohama 223-8522, 6Japan |
| 키워드 |
Thermoelectric material; SnAs-based layered hexagonal compound; EuSn<SUB>2</SUB>As<SUB>2</SUB>
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| E-Mail |
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