Yuefeng Yin

Abstract Mg3Bi2-xSbx compounds have emerged as promising mid-temperature thermoelectric materials, due to their excellent electrical performance and the ultralow thermal conductivity. In this study, we investigate the complex phonon interactions in Mg3Bi2-xSbx compounds and reveal nontrivial symmetry-protected topological crossings and avoided-crossing phenomena in the phonon dispersion, arising from the strong coupling between the acoustic and low-energy optical phonons.

Sb and Bi monolayers, as single-element ferroelectric materials with similar atomic structure, hold intrinsic piezoelectricity theoretically, which makes them highly promising for applications in functional nanodevices such as sensors and actuators. Here, using density functional theory calculations, we systematically explore the piezoelectric response of Sb and Bi monolayers. Our findings reveal that Sb exhibits a negative piezoelectric response, whereas Bi displays a positive one.