An experimental and theoretical approach for temperature-dependent Raman-active optical phonons driven thermal conductivity of layered PbBi2Se4 nano-flowers

Topologically active, crystalline layered PbBi2Se4 has been probed for significantly low thermal conductivity and excellent thermal properties. The present work focuses on the investigation of thermal properties of the PbBi2Se4 composite, such as diffusivity, effusivity, specific heat, Debye temperature, thermal conductivity, lattice thermal conductivity using temperature, and incident laser power-dependent Raman scattering. The thermal properties are very important for thermal energy harvesting applications. The obtained results have been substantiated with first-principles calculations. It is observed that the septuple interface Se atoms govern high-frequency Raman Active modes, and their role is crucial for thermal properties. High phonon density of states at low-frequency, strong phonon coupling drove scattering, and low phonon lifetime of optically active E-g(2) and A21g modes govern the low thermal conductivity (55 Wm -1 K-1). The thermal conductivity of PbBi2Se4 is an order of magnitude lower than the other ternary compounds from the PbxBi2ySe3x?y family but is comparable to that of transition metal chalcogenide materials (e. g. MoS2). The present work provides an efficient method to investigate the thermal conductivity of layered material. Further, it can be used to tune the thermal properties of the topological insulators by exploring the phonon dynamics.

Automated summary

The thermal properties of PbBi2Se4 composite, such as diffusivity, effusivity, specific heat, Debye temperature, thermal conductivity, and lattice thermal conductivity, have been investigated using temperature and incident laser power-dependent Raman scattering. The results provide insights into the thermal conductivity of layered materials and can be used to tune the thermal properties of topological insulators.