Lattice Transformation from 2D to Quasi 1D and Phonon Properties of Exfoliated ZrS₂ and ZrSe₂

Abstract

Recent reports on thermal and thermoelectric properties of emerging 2D materials have shown promising results. Among these materials are Zirconium-based chalcogenides such as zirconium disulfide (ZrS 2 ), zirconium diselenide (ZrSe 2 ), zirconium trisulfide (ZrS 3 ), and zirconium triselenide (ZrSe 3 ). Here, the thermal properties of these materials are investigated using confocal Raman spectroscopy. Two different and distinctive Raman signatures of exfoliated ZrX 2 (where X = S or Se) are observed. For 2D-ZrX 2 , Raman modes are in alignment with those reported in literature. However, for quasi 1D-ZrX 2 , Raman modes are identical to exfoliated ZrX 3 nanosheets, indicating a major lattice transformation from 2D to quasi-1D. Raman temperature dependence for ZrX 2 are also measured. Most Raman modes exhibit a linear downshift dependence with increasing temperature. However, for 2D-ZrS 2 , a blueshift for A1g mode is detected with increasing temperature. Finally, phonon dynamics under optical heating for ZrX 2 are measured. Based on these measurements, the calculated thermal conductivity and the interfacial thermal conductance indicate lower interfacial thermal conductance for quasi 1D-ZrX 2 compared to 2D-ZrX 2 , which can be attributed to the phonon confinement in 1D. The results demonstrate exceptional thermal properties for Zirconium-based materials, making them ideal for thermoelectric device applications and future thermal management strategies.