TY - JOUR
T1 - Quaternary Pavonites A1+xSn2-xBi5+xS10 (A+ = Li+, Na+)
T2 - Site Occupancy Disorder Defines Electronic Structure
AU - Khoury, Jason F.
AU - Hao, Shiqiang
AU - Stoumpos, Constantinos C.
AU - Yao, Zhenpeng
AU - Malliakas, Christos D.
AU - Aydemir, Umut
AU - Slade, Tyler J.
AU - Snyder, G. Jeffrey
AU - Wolverton, Chris
AU - Kanatzidis, Mercouri G.
N1 - Funding Information:
This work was supported by the National Science Foundation Grant DMR-1708254, as well as the NASA Science Mission Directorate’s Radioisotope Power Systems Thermoelectric Technology Development. S.H. and C.W. (DFT calculations) were supported by the Department of Energy, Office of Science Basic Energy Sciences Grant DE-SC0014520. C.D.M. was supported by IMSERC at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF NNCI-1542205); the State of Illinois; and International Institute for Nanotechnology (IIN). We acknowledge the use of QUEST, the supercomputer resource facility at Northwestern University. We thank Michael L. Aubrey for helpful discussions, and Daniel G. Chica for assisting in ammonia synthesis of Na2S and Li2S.
PY - 2018/2/19
Y1 - 2018/2/19
N2 - The field of mineralogy represents an area of untapped potential for the synthetic chemist, as there are numerous structure types that can be utilized to form analogues of mineral structures with useful optoelectronic properties. In this work, we describe the synthesis and characterization of two novel quaternary sulfides A1+xSn2-xBi5+xS10 (A = Li+, Na+). Though not natural minerals themselves, both compounds adopt the pavonite structure, which crystallizes in the C2/m space group and consists of two connected, alternating defect rock-salt slabs of varying thicknesses to create a three-dimensional lattice. Despite their commonalities in structure, their crystallography is noticeably different, as both structures have a heavy degree of site occupancy disorder that affects the actual positions of the atoms. The differences in site occupancy alter their electronic structures, with band gap values of 0.31(2) eV and 0.07(2) eV for the lithium and sodium analogues, respectively. LiSn2Bi5S10 exhibits ultralow thermal conductivity of 0.62 W m-1 K-1 at 723 K, and this result is corroborated by phonon dispersion calculations. This structure type is a promising host candidate for future thermoelectric materials investigation, as these materials have narrow band gaps and intrinsically low thermal conductivities.
AB - The field of mineralogy represents an area of untapped potential for the synthetic chemist, as there are numerous structure types that can be utilized to form analogues of mineral structures with useful optoelectronic properties. In this work, we describe the synthesis and characterization of two novel quaternary sulfides A1+xSn2-xBi5+xS10 (A = Li+, Na+). Though not natural minerals themselves, both compounds adopt the pavonite structure, which crystallizes in the C2/m space group and consists of two connected, alternating defect rock-salt slabs of varying thicknesses to create a three-dimensional lattice. Despite their commonalities in structure, their crystallography is noticeably different, as both structures have a heavy degree of site occupancy disorder that affects the actual positions of the atoms. The differences in site occupancy alter their electronic structures, with band gap values of 0.31(2) eV and 0.07(2) eV for the lithium and sodium analogues, respectively. LiSn2Bi5S10 exhibits ultralow thermal conductivity of 0.62 W m-1 K-1 at 723 K, and this result is corroborated by phonon dispersion calculations. This structure type is a promising host candidate for future thermoelectric materials investigation, as these materials have narrow band gaps and intrinsically low thermal conductivities.
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U2 - 10.1021/acs.inorgchem.7b03091
DO - 10.1021/acs.inorgchem.7b03091
M3 - Article
C2 - 29411610
AN - SCOPUS:85042198269
VL - 57
SP - 2260
EP - 2268
JO - Inorganic Chemistry
JF - Inorganic Chemistry
SN - 0020-1669
IS - 4
ER -