Tunable Intrinsic Phonon Mode versus Anomalous Thermal Transport in Two-Dimensional Strongly Anharmonic Group IB Chalcogenides A₂^IBSe_1/2Te_1/2 (A^IB = Cu, Ag, or Au)

Origin of positive/negative effects on pressure-dependent thermal conductivity: the role of bond strength and anharmonicity

“…The increased differences in X–Se atomic size and electronegativity from BeSe to CaSe are important factors in enhancing anharmonicity. 48,49 First, in the F 4̄3 m phase, the increase in atomic size competes with the strong covalent bond directionality to enhance the anharmonicity. The contour line of the F 4̄3 m phase is not axisymmetric along the bond direction, and the localized electrons increase from BeSe to CaSe in Fig.…”