Journal
JOURNAL OF ALLOYS AND COMPOUNDS
Volume 641, Issue -, Pages 30-36Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.jallcom.2015.04.048
Keywords
Nanostructured materials; Thermoelectric; Sintering; Ball milling
Categories
Funding
- NSF/DOE Joint Thermoelectric Partnership (NSF) [CBET-1048767]
- NSF [DMR-1229131, DMR-1122603.]
- Direct For Mathematical & Physical Scien
- Division Of Materials Research [1229131] Funding Source: National Science Foundation
- Div Of Chem, Bioeng, Env, & Transp Sys
- Directorate For Engineering [1048767] Funding Source: National Science Foundation
Ask authors/readers for more resources
Bulk nanostructured higher manganese silicide (HMS) samples with different grain size are prepared by melting, subsequent ball milling (BM), and followed by spark plasma sintering (SPS). The effects of BM time on the microstructures and thermoelectric properties of these samples are investigated. It is found that BM effectively reduces the grain size to about 90 nm in the sample after SPS, which leads to a decrease in both the thermal conductivity and electrical conductivity. By prolonging the BM time, MnSi and tungsten/carbon-rich impurity phases are formed due to the impact-induced decomposition of HMS and contamination from the tungsten carbide jar and balls during the BM, respectively. These impurities result in a reduced Seebeck coefficient and increased thermal conductivity above room temperature. The measured size-dependent lattice thermal conductivities agree qualitatively with the reported calculation results based on a combined phonon and diffuson model. The size effects are found to be increasingly significant as temperature decreases. Because of the formation of the impurity phases and a relatively large grain size, the ZT values are not improved in the ball-milled HMS samples. These findings suggest the need of alternative approaches for the synthesis of pure HMS with further reduced grain size and controlled impurity doping in order to enhance the thermoelectric figure-of-merit of HMS via nanostructuring. (C) 2015 Elsevier B.V. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available