Nanostructuring of Undoped ZnSb by Cryo-Milling
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We report the preparation of nanosized ZnSb powder by cryo-milling. The effect of cryo-milling then hot-pressing of undoped ZnSb was investigated and compared with that of room temperature ball-milling and hot-pressing under different temperature conditions. ZnSb is a semiconductor with favorable thermoelectric properties when doped. We used undoped ZnSb to study the effect of nanostructuring on lattice thermal conductivity, and with little contribution at room temperature from electronic thermal conductivity. Grain growth was observed to occur during hot-pressing, as observed by transmission electron microscopy and x-ray diffraction. The thermal conductivity was lower for cryo-milled samples than for room-temperature ball-milled samples. The thermal conductivity also depended on hot-pressing conditions. The thermal conductivity could be varied by a factor of two by adjusting the process conditions and could be less than a third that of single-crystal ZnSb.
KeywordsNanostructuring ZnSb thermal conductivity thermoelectric materials
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We thank Jaya Nolt of UCSB for performing XRD at different temperatures. X.S. is grateful for help with the rapid hot-press at California Institute of Technology (c/o Jeff Snyder) and use of high-temperature Hall setup. This work was supported by the Norwegian Research Council under contract NFR11-40-6321 (NanoThermo) and the University of Oslo. X.S. acknowledges financial support by a Kristine Bonnevie stipend from University of Oslo, a travel grant, and infrastructure grants from the Norwegian Nano-Network and from NorFab.
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