TY - JOUR
T1 - Large Thermal Conductivity Drops in the Diamondoid Lattice of CuFeS2 by Discordant Atom Doping
AU - Xie, Hongyao
AU - Su, Xianli
AU - Hao, Shiqiang
AU - Zhang, Cheng
AU - Zhang, Zhengkai
AU - Liu, Wei
AU - Yan, Yonggao
AU - Wolverton, Christopher
AU - Tang, Xinfeng
AU - Kanatzidis, Mercouri G.
N1 - Funding Information:
This work was supported by a grant from the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences under Award Number DE-SC0014520. The authors wish to acknowledge support from the National Basic Research Program of China (973 program) under project 2013CB632502, the Natural Science Foundation of China (Grant No. 51521001, 51632006) and the 111 Project of China (Grant No. B07040).
Publisher Copyright:
© 2019 American Chemical Society.
PY - 2019/11/27
Y1 - 2019/11/27
N2 - Doping in a lattice refers to the introduction of very small quantities of foreign atoms and has a generally small effect on decreasing the lattice thermal conductivity, unlike alloying which involves large fractions of other elements and strongly enhances point defect phonon scattering. Here, we report that, by alloying only 3% of In on the Cu sites of the diamond-like lattice of CuFeS2 chalcopyrite compound (Cu1-xInxFeS2, x = 0.03) has a disproportionally large effect in reducing the lattice thermal conductivity of the compound from 2.32 to 1.36 Wm-1K-1 at 630 K. We find that In is not fully ionized to +3 when on the Cu sublattice and exists mainly in the +1 oxidation state. The 5s2 lone pair of electrons of In+ makes this atom incompatible (referred to as discordant) with the tetrahedral geometry of the crystallographic site. This causes strong local bond distortions thereby softening the In-S and Cu-S chemical bonds and introducing localized low frequency vibrations. The latter couple with the base phonon frequencies of the CuFeS2 matrix enhancing the anharmonicity and decreasing the phonon velocity, and consequently the lattice thermal conductivity. The control material in which the In doping is on the Fe3+ site of the structure at the same doping level (and found in the site-compatible In3+ state), has a far smaller effect on the phonon scattering.
AB - Doping in a lattice refers to the introduction of very small quantities of foreign atoms and has a generally small effect on decreasing the lattice thermal conductivity, unlike alloying which involves large fractions of other elements and strongly enhances point defect phonon scattering. Here, we report that, by alloying only 3% of In on the Cu sites of the diamond-like lattice of CuFeS2 chalcopyrite compound (Cu1-xInxFeS2, x = 0.03) has a disproportionally large effect in reducing the lattice thermal conductivity of the compound from 2.32 to 1.36 Wm-1K-1 at 630 K. We find that In is not fully ionized to +3 when on the Cu sublattice and exists mainly in the +1 oxidation state. The 5s2 lone pair of electrons of In+ makes this atom incompatible (referred to as discordant) with the tetrahedral geometry of the crystallographic site. This causes strong local bond distortions thereby softening the In-S and Cu-S chemical bonds and introducing localized low frequency vibrations. The latter couple with the base phonon frequencies of the CuFeS2 matrix enhancing the anharmonicity and decreasing the phonon velocity, and consequently the lattice thermal conductivity. The control material in which the In doping is on the Fe3+ site of the structure at the same doping level (and found in the site-compatible In3+ state), has a far smaller effect on the phonon scattering.
UR - http://www.scopus.com/inward/record.url?scp=85075125067&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85075125067&partnerID=8YFLogxK
U2 - 10.1021/jacs.9b10983
DO - 10.1021/jacs.9b10983
M3 - Article
C2 - 31680516
AN - SCOPUS:85075125067
SN - 0002-7863
VL - 141
SP - 18900
EP - 18909
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 47
ER -