Journal
AIP ADVANCES
Volume 8, Issue 11, Pages -Publisher
AMER INST PHYSICS
DOI: 10.1063/1.5063274
Keywords
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Funding
- Nano-Material Technology Development Program through the National Research Foundation of Korea (NRF) - Ministry of Education, Science and Technology [2011-0030147]
- Materials and Components Technology Development Program of MOTIE/KEIT [10063286]
- National Research Foundation of Korea [2011-0030147] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
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The InTe has intrinsically low lattice thermal conductivity kappa(L) originating from the anharmonic bonding of In1+ ion in the lattice, which scatters the phonons. Here we report the enhancement of thermoelectric properties in Te-deficient InTe1-delta (delta = 0, 0.01, 0.1, and 0.2) polycrystalline compounds by lattice softening and energy band gap opening. Te-deficiency gives rise to more weak chemical bonding between In1+ atoms and In3+Te2- clusters than those of pristine InTe, resulting in the reduction of kappa(L) near the room temperature. The weak ionic bonding is confirmed by the increase of lattice volume from the X-ray diffraction and lattice softening by the decrease of Debye temperature with increasing Te-deficiency. We observed the low lattice thermal conductivity kappa(L) of 0.53 W m(-1) K-1 at 300 K for InTe0.99, which is about 25 % decreased value than those of InTe. The Te-deficiency also induces energy band gap so that the electrical resistivity and Seebeck coefficient are increased due to the decrease of carrier concentration. Temperature-dependent thermoelectric properties shows the high Seebeck coefficient at high temperature and high electrical conductivity near room temperature, resulting in the temperature-insensitive high power factor S-2 sigma over a wide temperature range. Owing to the temperature-insensitive high power factor and intrinsic low lattice thermal conductivity by Te-deficiency, the thermoelectric performances of figure-of-merit ZT and engineering ZT(eng) are enhanced at mild temperature range (<= 550 K). (C) 2018 Author(s).
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