Investigation on transport properties and anomalously heat-carrying optical phonons in KXY (X = Ca, Mg; Y = Sb, Bi)

In this work, we systematically studied the thermal transport properties of ternary zintl compound KXY using self-consistent phonon theory combined with compressive sensing technology and the Boltzmann transport equation. The effects of quartic anharmonic induced phonon renormalization and 4 -phonon scattering on the results are fully considered. Vibrational mode visualization reveals that the anomalous contribution of optical phonons to lattice thermal conductivity in KCaBi originates from high-speed out-of-phase vibrations of Ca atoms. We analyzed the microscopic mechanism of heat transport from the perspective of atomic bonding combined with the results of group velocity, scattering rate, Gru center dot neisen parameter, mean free path, etc. In addition, we verified and predicted the mechanical properties in KXY by calculation.(c) 2023 Elsevier Ltd. All rights reserved.

Automated summary

In this work, the thermal transport properties of ternary zintl compound KXY were systematically studied using self-consistent phonon theory combined with compressive sensing technology and the Boltzmann transport equation. The effects of quartic anharmonic induced phonon renormalization and 4-phonon scattering on the results were fully considered. Vibrational mode visualization revealed that the anomalous contribution of optical phonons to lattice thermal conductivity in KCaBi originated from high-speed out-of-phase vibrations of Ca atoms. The microscopic mechanism of heat transport was analyzed from the perspective of atomic bonding combined with the results of group velocity, scattering rate, Gru center dot neisen parameter, mean free path, etc. Additionally, the mechanical properties in KXY were verified and predicted through calculation. (c) 2023 Elsevier Ltd. All rights reserved.