title: Yb14MgBi11: structure, thermoelectric properties and the effect of the structure on low lattice thermal conductivity.
abstract: Zintl phases Yb14MnSb11and Yb14MgSb11, which share the same complex structure type, have been demonstrated as the best p-type thermoelectric materials for the high temperature region (800-1200 K). A new iso-structural compound, Yb14MgBi11, was synthesized in order to investigate the structure and thermoelectric properties of the Bi analogs. Yb14MgBi11crystallizes in the Ca14AlSb11structure-type with the space group I41/acd [a = 16.974(2) Å, c = 22.399(4) Å, V = 6454(2) Å3, R1/wR2= 0.0238/0.0475]. The structure follows the previous description of this structure type and the trend observed in previous analogs. Thermoelectric properties of Yb14MgBi11are measured together with Yb14MnBi11and both compounds are metallic. Compared to Yb14MgSb11, Yb14MgBi11has a higher carrier concentration with a similar mobility and effective mass. The lattice thermal conductivity of Yb14MgBi11is extremely low, which is as low as 0.16-0.36 W(mK)-1. The zT values of Yb14MgBi11and Yb14MnBi11reach 0.2 at 875 K.
authors.affiliation: Chemistry Department, One Shields Avenue, University of California, Davis, 95616USA. smkauzlarich@ucdavis.edu.
authors.forename: Yufei
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Chemistry Department, One Shields Avenue, University of California, Davis, 95616USA. smkauzlarich@ucdavis.edu.
authors.forename: Susan M
authors.identifier: http://orcid.org/0000-0002-3627-237X
authors.initials: SM
authors.lastname: Kauzlarich