| 作成者 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 本文言語 |
|
| 出版者 |
|
| 発行日 |
|
| 収録物名 |
|
| 巻 |
|
| 号 |
|
| 開始ページ |
|
| 終了ページ |
|
| アクセス権 |
|
| 権利関係 |
|
|
|
| 関連DOI |
|
| 関連URI |
|
| 概要 |
We report the preparations, thermoelectric and magnetic properties, and electronic structures of Cu–Ti–S systems, namely, cubic thiospinel c-Cu_<1–x>Ti_2S_4 (x ≤ 0.375), a derivative cubic and Ti-rich... phase c-Cu_<1–x>Ti_<2.25>S_4 (x = 0.5, 0.625), and a rhombohedral phase r-CuTi_2S_4. All samples have the target compositions except for r-CuTi_2S_4, whose actual composition is Cu_<1.14>Ti_<1.80>S_4. All of the phases have n-type metallic character and exhibit Pauli paramagnetism, as proven by experiments and first-principles calculations. The Cu and Ti deficiencies in c-Cu_<1–x>Ti_2S_4 and r-CuTi_2S_4, respectively, decrease the electron-carrier concentration, whereas the “excess” of Ti ions in c-Cu_<1–x>Ti_<2.25>S_4 largely increases it. For r-CuTi_2S_4, the reduced carrier concentration increases the electrical resistivity and Seebeck coefficient, leading to the highest thermoelectric power factor of 0.5 mW K^<–2> m^<–1> at 670 K. For all of the Cu–Ti–S phases, the thermal conductivity at 670 K is 3.5–5 W K^<–1> m^<–1>, where the lattice part of the conductivity is as low as 1 W K^<–1> m^<–1> at 670 K. As a result, r-CuTi_2S_4 shows the highest dimensionless thermoelectric figure of merit ZT of 0.2. The present systematic study on the Cu–Ti–S systems provides insights into the structural design of thermoelectric materials based on Cu–M–S (M = transition-metal elements).続きを見る
|
Mendeley出力
