Suppressed Lone Pair Electrons Explain Unconventional Rise of Lattice Thermal Conductivity in Defective Crystalline Solids

Hanhwi Jang; Michael Y. Toriyama; Stanley Abbey; Brakowaa Frimpong; G. Jeffrey Snyder; Yeon Sik Jung; Min Wook Oh

doi:10.1002/advs.202308075

Suppressed Lone Pair Electrons Explain Unconventional Rise of Lattice Thermal Conductivity in Defective Crystalline Solids

Hanhwi Jang, Michael Y. Toriyama, Stanley Abbey, Brakowaa Frimpong, G. Jeffrey Snyder^*, Yeon Sik Jung^*, Min Wook Oh^*

^*Corresponding author for this work

Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

Abstract

Manipulating thermal properties of materials can be interpreted as the control of how vibrations of atoms (known as phonons) scatter in a crystal lattice. Compared to a perfect crystal, crystalline solids with defects are expected to have shorter phonon mean free paths caused by point defect scattering, leading to lower lattice thermal conductivities than those without defects. While this is true in many cases, alloying can increase the phonon mean free path in the Cd-doped AgSnSbSe₃ system to increase the lattice thermal conductivity from 0.65 to 1.05 W m⁻¹ K⁻¹ by replacing 18% of the Sb sites with Cd. It is found that the presence of lone pair electrons leads to the off-centering of cations from the centrosymmetric position of a cubic lattice. X-ray pair distribution function analysis reveals that this structural distortion is relieved when the electronic configuration of the dopant element cannot produce lone pair electrons. Furthermore, a decrease in the Grüneisen parameter with doping is experimentally confirmed, establishing a relationship between the stereochemical activity of lone pair electrons and the lattice anharmonicity. The observed “harmonic” behavior with doping suggests that lone pair electrons must be preserved to effectively suppress phonon transport in these systems.

Original language	English (US)
Article number	2308075
Journal	Advanced Science
Volume	11
Issue number	24
DOIs	https://doi.org/10.1002/advs.202308075
State	Published - Jun 26 2024

Funding

This work was supported by the research fund of Hanbat National University in 2019. This work made use of the IMSERC X\u2010RAY facility at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS\u20102025633), and Northwestern University. M.Y.T. was funded by the United States Department of Energy through the Computational Science Graduate Fellowship (DOE CSGF) under grant number DE\u2010SC0020347. This research was supported in part by the computational resources and staff contributions provided for the Quest high\u2010performance computing facility at Northwestern University, which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology.

Keywords

defect engineering
density functional theory
lone pair electrons
thermal conductivity
thermoelectrics

ASJC Scopus subject areas

Medicine (miscellaneous)
General Chemical Engineering
General Materials Science
Biochemistry, Genetics and Molecular Biology (miscellaneous)
General Engineering
General Physics and Astronomy

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title = "Suppressed Lone Pair Electrons Explain Unconventional Rise of Lattice Thermal Conductivity in Defective Crystalline Solids",

abstract = "Manipulating thermal properties of materials can be interpreted as the control of how vibrations of atoms (known as phonons) scatter in a crystal lattice. Compared to a perfect crystal, crystalline solids with defects are expected to have shorter phonon mean free paths caused by point defect scattering, leading to lower lattice thermal conductivities than those without defects. While this is true in many cases, alloying can increase the phonon mean free path in the Cd-doped AgSnSbSe3 system to increase the lattice thermal conductivity from 0.65 to 1.05 W m−1 K−1 by replacing 18% of the Sb sites with Cd. It is found that the presence of lone pair electrons leads to the off-centering of cations from the centrosymmetric position of a cubic lattice. X-ray pair distribution function analysis reveals that this structural distortion is relieved when the electronic configuration of the dopant element cannot produce lone pair electrons. Furthermore, a decrease in the Gr{\"u}neisen parameter with doping is experimentally confirmed, establishing a relationship between the stereochemical activity of lone pair electrons and the lattice anharmonicity. The observed “harmonic” behavior with doping suggests that lone pair electrons must be preserved to effectively suppress phonon transport in these systems.",

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author = "Hanhwi Jang and Toriyama, {Michael Y.} and Stanley Abbey and Brakowaa Frimpong and Snyder, {G. Jeffrey} and Jung, {Yeon Sik} and Oh, {Min Wook}",

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Suppressed Lone Pair Electrons Explain Unconventional Rise of Lattice Thermal Conductivity in Defective Crystalline Solids

Abstract

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