TY - JOUR
T1 - Two-Dimensional CsAg5Te3- xSx Semiconductors
T2 - Multi-anion Chalcogenides with Dynamic Disorder and Ultralow Thermal Conductivity
AU - Hodges, James M.
AU - Xia, Yi
AU - Malliakas, Christos D.
AU - Alexander, Grant C.B.
AU - Chan, Maria K.Y.
AU - Kanatzidis, Mercouri G.
N1 - Funding Information:
This work was supported by the Midwest Integrated Center for Computational Materials (MICCoM) as part of the Computational Materials Sciences Program funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division (5J-30161-0010A). Use of the Center for Nanoscale Materials, an Office of Science User Facility, was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the U.S. Department of Energy, Office of Science, under Contract DE-AC02-05CH11231. Use was made of the IMSERC X-ray Facility at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205), the State of Illinois, and the International Institute for Nanotechnology (IIN).
PY - 2018/10/23
Y1 - 2018/10/23
N2 - Metal chalcogenides underpin a wide variety of energy-related applications and are ideal systems for probing lattice dynamics and fundamental transport phenomena. Here we describe the synthesis and transport properties of CsAg5TeS2 and its solid solution CsAg5Te3-xSx (x = 1-2), new semiconductors with tunable band gaps ranging from 0.17 to 0.30 eV. CsAg5TeS2 has a fully ordered two-dimensional structure that includes a group of Ag atoms in a heteroleptic tetrahedral coordination geometry (AgTe2S2). Single-crystal X-ray diffraction indicates that the compounds crystallize in the tetragonal space group P4/mmm, while pair distribution function (PDF) analysis reveals off-centering at the heteroleptic Ag sites, signifying the lower-symmetry I4/mcm space group. The underlying disorder acts as a phonon-blocking mechanism that helps facilitate an ultralow lattice thermal conductivity below 0.40 W·m-1·K-1 at ∼300 K, highlighting the importance of local disorder in thermal transport. Density functional theory provides additional insight into the electronic and thermal properties of the materials, which are good candidates for p-type thermoelectrics.
AB - Metal chalcogenides underpin a wide variety of energy-related applications and are ideal systems for probing lattice dynamics and fundamental transport phenomena. Here we describe the synthesis and transport properties of CsAg5TeS2 and its solid solution CsAg5Te3-xSx (x = 1-2), new semiconductors with tunable band gaps ranging from 0.17 to 0.30 eV. CsAg5TeS2 has a fully ordered two-dimensional structure that includes a group of Ag atoms in a heteroleptic tetrahedral coordination geometry (AgTe2S2). Single-crystal X-ray diffraction indicates that the compounds crystallize in the tetragonal space group P4/mmm, while pair distribution function (PDF) analysis reveals off-centering at the heteroleptic Ag sites, signifying the lower-symmetry I4/mcm space group. The underlying disorder acts as a phonon-blocking mechanism that helps facilitate an ultralow lattice thermal conductivity below 0.40 W·m-1·K-1 at ∼300 K, highlighting the importance of local disorder in thermal transport. Density functional theory provides additional insight into the electronic and thermal properties of the materials, which are good candidates for p-type thermoelectrics.
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U2 - 10.1021/acs.chemmater.8b03306
DO - 10.1021/acs.chemmater.8b03306
M3 - Article
AN - SCOPUS:85054629976
VL - 30
SP - 7245
EP - 7254
JO - Chemistry of Materials
JF - Chemistry of Materials
SN - 0897-4756
IS - 20
ER -