Enhanced Thermoelectric Properties of Selenium-Deficient Layered TiSe2鈥?i>x: A Charge-Density-Wave Material
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- 作者：Ranu Bhatt ; Shovit Bhattacharya ; Ranita Basu ; Sajid Ahmad ; A. K. Chauhan ; G. S. Okram ; Pramod Bhatt ; Mainak Roy ; M. Navaneethan ; Y. Hayakawa ; A. K. Debnath ; Ajay Singh ; D. K. Aswal ; S. K. Gupta
- 刊名：ACS Applied Materials & Interfaces
- 出版年：2014
- 出版时间：November 12, 2014
- 年：2014
- 卷：6
- 期：21
- 页码：18619-18625
- 全文大小：494K
- ISSN：1944-8252
文摘
In the present work, we report on the investigation of low-temperature (300鈥? K) thermoelectric properties of hot-pressed TiSe2, a charge-density-wave (CDW) material. We demonstrate that, with increasing hot-pressing temperature, the density of TiSe2 increases and becomes nonstoichiometric owing to the loss of selenium. X-ray diffraction, scanning electron microscopy, and transimission electron microscopy results show that the material consists of a layered microstructure with several defects. Increasing the hot-press temperature in nonstoichiometric TiSe2 leads to a reduction of the resistivity and enhancement of the Seebeck coefficient in concomitent with suppression of CDW. Samples hot-pressed at 850 掳C exhibited a minimum thermal conductivity (魏) of 1.5 W/m路K at 300 K that, in turn, resulted in a figure-of-merit (ZT) value of 0.14. This value is higher by 6 orders of magnitude compared to 1.49 脳 10鈥? obtained for cold-pressed samples annealed at 850 掳C. The enhancement of ZT in hot-pressed samples is attributed to (i) a reduced thermal conductivity owing to enhanced phonon scattering and (ii) improved power factor (伪2蟽).