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- Title
Mechanical alloying-spark plasma sintering synthesis and thermoelectric properties of n-type NiSe semiconductors: analysis of intrinsic defects and phase structures.
- Authors
Zheng, Li-Jun; Zhang, Bo-Ping; Han, Cheng-Gong; Pei, Jun; Chen, Ning
- Abstract
A series of bulk samples NiSe ( x = 0, 0.01, 0.02, 0.06) were prepared by mechanical alloying (MA) and spark plasma sintering (SPS). The effect of excessive selenium content ( x) on the phase structure, microstructure and thermoelectric properties was investigated. The formation energy of intrinsic defects in NiSe was calculated using first principle theory. The added selenium initially entered into the Se vacancy ( $$V_{Se}^{ \cdot }$$ ) which is resulted from the Se volatilization during the MA and/or SPS process and subsequently into the interstitial sites ( $$Se_{i}^{\prime }$$ ). An improved absolute value of Seebeck coefficient (| α|) 9.27 μVK at 323 K for the NiSe was reached along with an inversely varied electrical conductivity ( σ) as increasing x. A minimum thermal conductivity ( κ) value 3.43 Wm K was achieved at 323 K for the NiSe, along with a high ZT value 0.0049 at 323 K for the NiSe among NiSe system. Our work provides a preliminary approach towards TE performance enhancement in n-type NiSe semiconductors via tailoring Se content in a nonstoichiometry, and will certainly be of value for further exploration of high performance NiSe semiconductors by either doping or microstructure controlling.
- Subjects
MECHANICAL alloying; SINTERING; SELENIUM; MICROSTRUCTURE; THERMOELECTRICITY
- Publication
Journal of Materials Science: Materials in Electronics, 2016, Vol 27, Issue 8, p8363
- ISSN
0957-4522
- Publication type
Article
- DOI
10.1007/s10854-016-4847-0