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1. Magneto-thermal conductivity effect and enhanced thermoelectric figure of merit in Ag2Te

   https://doi.org/10.1063/5.0131326  

   Hirata, Keisuke; Kuga, Kentaro; Matsunami, Masaharu; Zhu, Minyue; Heremans, Joseph_P; Takeuchi, Tsunehiro (January 2023, AIP Advances)

   In this study, we report a large magneto-thermal conductivity effect, potentially usable in heat flow switches and thermoelectric devices, in Ag2Te over a wide temperature range, including room temperature. When a magnetic field of μ0H = 9 T is applied to Ag2Te at 300 K along the direction perpendicular to the heat and electric currents, the thermal conductivity κ decreases by a remarkable 61%. This effect is mainly caused by the suppressed electronic thermal conductivity in association with a significant magnetoresistance effect, but the suppression of the thermal conductivity is larger than that of the electrical conductivity, presumably due to a field-induced decrease in the Lorenz ratio. Its very low lattice thermal conductivity, as low as 0.5 W m−1 K−1, also greatly contributes to the large relative magneto-thermal conductivity effect. The significant decrease in thermal conductivity and the 18% increase in the Seebeck coefficient S lead to a nearly 100% increase in the thermoelectric figure of merit zT = S2σTκ−1 despite the 43% decrease in electrical conductivity σ. 

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2. Thermal Conductivity of CaSrFe0.75Co0.75Mn0.5O6-δ

   https://doi.org/10.54963/neea.v3i1.222  

   Medicine_Cloud, Gillian; Guinn, Mandy; Krishna_Hona, Ram (January 2024, New Energy Exploitation and Application)

   CaSrFe0.75Co0.75Mn0.5O6-δ, an oxygen-deficient perovskite, had been reported for its better electrocatalytic properties of oxygen evolution reaction. It is essential to investigate different properties such as the thermal conductivity of such efficient functional materials. The thermal conductivity of CaSrFe0.75Co0.75Mn0.5O6-δ is a critical parameter for understanding its thermal transport properties and potential applications in energy conversion and electronic devices. In this study, the authors present an investigation of the thermal conductivity of CaSrFe0.75Co0.75Mn0.5O6-δ at room temperature for its thermal insulation property study. Experimental measurement was conducted using a state-of-the-art thermal characterization technique, Thermtest thermal conductivity meter. The thermal conductivity of CaSrFe0.75Co0.75Mn0.5O6-δ was found to be 0.724 W/m/K at 25 °C, exhibiting a notable thermal insulation property i.e., low thermal conductivity. 

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3. Thermal Conductivity of CaSrFe2O6-δ

   https://doi.org/10.19080/AJOP.2024.06.555685  

   Hona, Ram Krishna (January 2024, Academic Journal of Polymer Science)

   unknown (Ed.)

   The thermal conductivity of CaSrFe2O6-δ, an oxygen-deficient perovskite, is a critical parameter for understanding its thermal transport properties and potential applications in energy conversion and electronic devices. In this study, we present an investigation of the thermal conductivity of CaSrFe2O6-δ at room temperature for its thermal insulation property study. Experimental measurement was conducted using a state-of-the-art thermal characterization technique, Thermtest thermal conductivity meter. The thermal conductivity of CaSrFe2O6-δ was found to be 0.574W/m/K, exhibiting a notable thermal insulation property. 

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4. First-principles prediction of thermal conductivity of bulk hexagonal boron nitride

   https://doi.org/10.1063/5.0210935  

   Guo, Ziqi; Han, Zherui; Alkandari, Abdulaziz; Khot, Krutarth; Ruan, Xiulin (April 2024, Applied Physics Letters)

   Despite its importance, a sophisticated theoretical study of thermal conductivity in bulk h-BN has been lacking to date. In this study, we predict thermal conductivity in bulk h-BN crystals using first-principles predictions and the Boltzmann transport equation. We consider three-phonon (3ph) scattering, four-phonon (4ph) scattering, and phonon renormalization. Our predicted thermal conductivity is 363 and 4.88 W/(m K) for the in-plane and out-of-plane directions at room temperature, respectively. Further analysis reveals that 4ph scattering reduces thermal conductivity, while phonon renormalization weakens phonon anharmonicity and increases thermal conductivity. Eventually, the in-plane and out-of-plane thermal conductivities show intriguing ∼T−0.627 and ∼T−0.568 dependencies, respectively, far deviating from the traditional 1/T relation. 

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5. Thermal Conductivity of BAs under Pressure

   https://doi.org/10.1002/aelm.202200017  

   Hou, Songrui; Sun, Bo; Tian, Fei; Cai, Qingan; Xu, Youming; Wang, Shanmin; Chen, Xi; Ren, Zhifeng; Li, Chen; Wilson, Richard_B (July 2022, Advanced Electronic Materials)

   Abstract The thermal conductivity of boron arsenide (BAs) is believed to be influenced by phonon scattering selection rules due to its special phonon dispersion. Compression of BAs leads to significant changes in phonon dispersion, which allows for a test of first principles theories for how phonon dispersion affects three‐ and four‐phonon scattering rates. This study reports the thermal conductivity of BAs from 0 to 30 GPa. Thermal conductivity vs. pressure of BAs is measured by time‐domain thermoreflectance with a diamond anvil cell. In stark contrast to what is typical for nonmetallic crystals, BAs is observed to have a pressure independent thermal conductivity below 30 GPa. The thermal conductivity of nonmetallic crystals typically increases upon compression. The unusual pressure independence of BAs's thermal conductivity shows the important relationship between phonon dispersion properties and three‐ and four‐phonon scattering rates. 

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