@article{622bc27b226643fe850dc2b5a618e2ab,
title = "Mg Deficiency in Grain Boundaries of n-Type Mg3Sb2 Identified by Atom Probe Tomography",
abstract = "Highly resistive grain boundaries significantly reduce the electrical conductivity that compromises the thermoelectric figure-of-merit zT in n-type polycrystalline Mg3Sb2. In this work, discovered is a Mg deficiency near grain boundaries using atom-probe tomography. Approximately 5 at% of Mg deficiency is observed uniformly in a 10 nm region along the grain boundary without any evidence of a stable secondary or impurity phase. The off-stoichiometry can prevent n-type dopants from providing electrons, lowering the local carrier concentration near the grain boundary and thus the local conductivity. This observation explains how nanometer scale compositional variations can dramatically determine thermoelectric zT, and provides concrete strategies to reduce grain-boundary resistance and increase zT in Mg3Sb2-based materials.",
keywords = "atom-probe tomography, grain boundary, thermoelectrics",
author = "Kuo, {Jimmy Jiahong} and Yuan Yu and Kang, {Stephen Dongmin} and Oana Cojocaru-Mir{\'e}din and Matthias Wuttig and Snyder, {G. Jeffrey}",
note = "Funding Information: J.J.K. carried out synthesis, characterization, and APT measurements at Northwestern University; Y.Y. performed APT measurement and analysis at RWTH Aachen. J.J.K., Y.Y., S.D.K., O.C.-M., M.W., and G.J.S. prepared and edited the manuscript. Y.Y., O.C.M., and M.W. acknowledge the financial support by the DPG (SFB 917). J.J.K. acknowledges NSF DMREF (grant nos. 1334713, 1334351, and 1333335) for support of this research. This work made use of the Northwestern University Center for Atom-Probe Tomography (NUCAPT) and the EPIC facility of Northwestern University's NUANCE Center. The LEAP tomograph at NUCAPT was purchased and upgraded with grants from the NSF-MRI (DMR-0420532) and ONR-DURIP (N00014-0400798, N00014-0610539, N00014-0910781, N00014-1712870) programs. NUCAPT received support from the MRSEC program (NSF DMR-1720139) at the Materials Research Center, the SHyNE Resource (NSF ECCS-1542205), and the Initiative for Sustainability and Energy (ISEN) at Northwestern University. The NUANCE Center received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1720139) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. Funding Information: J.J.K. carried out synthesis, characterization, and APT measurements at Northwestern University; Y.Y. performed APT measurement and analysis at RWTH Aachen. J.J.K., Y.Y., S.D.K., O.C.-M., M.W., and G.J.S. prepared and edited the manuscript. Y.Y., O.C.M., and M.W. acknowledge the financial support by the DPG (SFB 917). J.J.K. acknowledges NSF DMREF (grant nos. 1334713, 1334351, and 1333335) for support of this research. This work made use of the Northwestern University Center for Atom-Probe Tomography (NUCAPT) and the EPIC facility of Northwestern University{\textquoteright}s NUANCE Center. The LEAP tomograph at NUCAPT was purchased and upgraded with grants from the NSF-MRI (DMR-0420532) and ONR-DURIP (N00014-0400798, N00014-0610539, N00014-0910781, N00014-1712870) programs. NUCAPT received support from the MRSEC program (NSF DMR-1720139) at the Materials Research Center, the SHyNE Resource (NSF ECCS-1542205), and the Initiative for Sustainability and Energy (ISEN) at Northwestern University. The NUANCE Center received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1720139) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. Publisher Copyright: {\textcopyright} 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim",
year = "2019",
month = jul,
day = "9",
doi = "10.1002/admi.201900429",
language = "English (US)",
volume = "6",
journal = "Advanced Materials Interfaces",
issn = "2196-7350",
publisher = "John Wiley and Sons Ltd",
number = "13",
}