Investigating Carbon Telluride Compounds via First-Principles Calculations: Structural, Property, and High-Pressure Response Analyses

The structural stability, mechanical properties, electronic transport characteristics, and phonon dynamics of three predicted C–Te compounds (CTe, CTe 2, and C 3 Te 8 ) under high pressure were systematically examined using first-principles calculations based on density functional theory. Among them, triclinic C 3 Te 8 shows the lowest stability and cannot exist stably even at zero temperature and pressure. In contrast, orthorhombic CTe 2 remains stable up to about 5 GPa, beyond which pressure-induced phase transition or decomposition occurs. Tetragonal CTe has the highest stability, maintaining a phonon spectrum without imaginary frequencies up to 10 GPa. Both CTe and CTe 2 compounds exhibit a combination of polar covalent and van der Waals bonding. Calculations of the band structure and electron transport properties reveal that CTe is a metal, while CTe 2 is a direct bandgap semiconductor with an intrinsic band gap ( E g ) of 1.387 eV. With increasing pressure, CTe 2 evolves from a direct to an indirect band gap semiconductor and finally metallizes. The calculated room-temperature carrier mobilities of CTe 2 along the [001] direction reach 83.74 cm 2 /(V·s) for electrons and 368.02 cm 2 /(V·s) for holes, representing the maximum values for both carrier types. Furthermore, pressure-dependent infrared and Raman spectra of both CTe and CTe 2 have been systematically computed, providing essential theoretical reference for subsequent experimental identification of their spectroscopic characteristics.