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arXiv · 2411.10738

Structural origins of ultra-low glass-like thermal conductivity in AgGaGe3Se8

Peter Skjøtt Thorup·Rasmus Baden Stubkjær·Kim-Khuong Huynh·Pavankumar Ventrapati·Emilie Skytte Vosegaard·Bo Brummerstedt Iversen
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Abstract

Materials with a low thermal conductivity are important for a variety of applications such as thermal barrier coatings and thermoelectrics, and understanding the underlying mechanisms of low heat transport, and relating them to structural features, remains a central goal within material science. Here, we report on the ultra-low thermal conductivity of the quarternary silver chalcogenide AgGaGe3Se8 with a remarkable value of only 0.2 Wm-1K-1 at room temperature, and an unusual glass-like thermal behavior from 2 K to 700 K. The ultra-low thermal conductivity is linked to a disordered nature of Ag in the structure, displaying extremely large Ag atomic displacement parameters obtained from multi-temperature synchrotron powder X-ray scattering measurements, and Ag ionic conductivity at elevated temperatures. Additionally, signs of structural anharmonicity and soft bonding are evident from a low temperature Boson peak in the heat capacity and a low Debye temperature of 147 K.

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Peter Skjøtt Thorup, Rasmus Baden Stubkjær, Kim-Khuong Huynh, Pavankumar Ventrapati, Emilie Skytte Vosegaard, Bo Brummerstedt Iversen. 2024-11-16. Structural origins of ultra-low glass-like thermal conductivity in AgGaGe3Se8. https://arxiv.org/abs/2411.10738

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