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Achieving zT > 1 in Inexpensive Zintl Phase Ca_9Zn_(4+x)Sb_9 by Phase Boundary Mapping

Ohno, Saneyuki and Aydemir, Umut and Amsler, Maximilian and Pöhls, Jan-Hendrik and Chanakian, Sevan and Zevalkink, Alex and White, Mary Anne and Bux, Sabah K. and Wolverton, Chris and Snyder, G. Jeffrey (2017) Achieving zT > 1 in Inexpensive Zintl Phase Ca_9Zn_(4+x)Sb_9 by Phase Boundary Mapping. Advanced Functional Materials, 27 (20). Art. No. 1606361. ISSN 1616-301X.

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Complex multinary compounds (ternary, quaternary, and higher) offer countless opportunities for discovering new semiconductors for applications such as photovoltaics and thermoelectrics. However, controlling doping has been a major challenge in complex semiconductors as there are many possibilities for charged intrinsic defects (e.g., vacancies, interstitials, antisite defects) whose energy depends on competing impurity phases. Even in compounds with no apparent deviation from a stoichiometric nominal composition, such defects commonly lead to free carrier concentrations in excess of 10^(20) cm^(−3). Nevertheless, by slightly altering the nominal composition, these defect concentrations can be tuned with small variation of the chemical potentials (composition) of each element. While the variation of chemical composition is undetectable, it is shown that the changes can be inferred by mapping (in nominal composition space) the boundaries where different competing impurity phases form. In the inexpensive Zintl compound Ca_9Zn_(4+x)Sb_9, the carrier concentrations can be finely tuned within three different three-phase regions by altering the nominal composition (x = 0.2–0.8), enabling the doubling of thermoelectric performance (zT). Because of the low thermal conductivity, the zT can reach as high as 1.1 at 875 K, which is one of the highest among the earth abundant p-type thermoelectrics with no ion conducting.

Item Type:Article
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URLURL TypeDescription
White, Mary Anne0000-0001-8142-0004
Snyder, G. Jeffrey0000-0003-1414-8682
Alternate Title:Achieving zT > 1 in Inexpensive Zintl Phase Ca9Zn4+xSb9 by Phase Boundary Mapping
Additional Information:© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Received: December 2, 2016; Revised: February 3, 2017; Published online: March 29, 2017. This work was supported by the NASA Science Mission Directorate's Radioisotope Power Systems Thermoelectric Technology Development. S.O. acknowledges the financial assistance of Japan Student Service Organization (JASSO) and would like to thank Stephen Dongmin Kang and Max Wood for the helpful discussions. M.A.W. acknowledges the support of NSERC and the Materials Characterization Facilities at Dalhousie University's Institute for Research in Materials. J.-H.P. is grateful to the NSERC CREATE DREAMS (Dalhousie Research in Energy, Advanced Materials and Sustainability program) for funding. M.A. acknowledges the support from the Novartis Universität Basel Excellence Scholarship for Life Sciences and the Swiss National Science Foundation (Grant No. P300P2-158407). C.W. (DFT calculations) acknowledges the support from the DOE (Grant No. DE-FG02-07ER46433). The Swiss National Supercomputing Center in Lugano (Project s499, s621, and s700), the Extreme Science and Engineering Discovery Environment (XSEDE) (which was supported by the National Science Foundation Grant No. OCI-1053575), the Bridges system at the Pittsburgh Supercomputing Center (PSC) (which was supported by the NSF Award No. ACI-1445606), and the National Energy Research Scientific Computing Center (DOE: DE-AC02-05CH11231), are gratefully acknowledged.
Funding AgencyGrant Number
Japan Student Service Organization (JASSO)UNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Dalhousie UniversityUNSPECIFIED
Novartis UniversitätUNSPECIFIED
Swiss National Science Foundation (SNSF)P300P2-158407
Department of Energy (DOE)DE-FG02-07ER46433
Department of Energy (DOE)DE-AC02-05CH11231
Subject Keywords:energy conversion; phase boundary mapping; semiconductors; thermoelectrics; Zintl phases
Issue or Number:20
Record Number:CaltechAUTHORS:20170329-142514472
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Official Citation:S. Ohno, U. Aydemir, M. Amsler, J.-H. Pöhls, S. Chanakian, A. Zevalkink, M. A. White, S. K. Bux, C. Wolverton, G. J. Snyder, Adv. Funct. Mater. 2017, 27, 1606361
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:75519
Deposited By: Tony Diaz
Deposited On:29 Mar 2017 22:04
Last Modified:03 Oct 2019 16:51

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