Layered GeP2S6, GeP2Se6, GeP2Te6, SnP2S6, SnP2Se6, and SnP2Te6 Polar Crystals with Semiconductor-Metal Transitions Induced by Pressure or Chemical Composition

Family of phosphorus-containing MM'P2S(Se)(6) chalcogenide materials with including promising layered ferrielectric CuInP2S6 and three-dimensional ferroelectric Sn2P2S6 crystals can be extended by searching for new van der Waals compounds of SnP2S6 type. New SnP2Se6, SnP2Te6, GeP2S6, GeP2Se6, and GeP2Te6 compounds with layered rhombohedral structure R3 are predicted by DFT calculations in GGA approximation. Variation of electron and phonon spectra is traced for Sn -> Ge substitution in the cation sublattice and for compounds with S, Se, or Te in anion sublattice. A polar metal state is expected at normal pressure in layered GeP2Te6 crystal. Softening of the phonon spectrum and metallization was found for SnP2S6 crystal at a pressure of about 80 GPa.

Automated summary

The family of phosphorus-containing chalcogenide materials can be extended by searching for new van der Waals compounds, with potential new properties predicted through DFT calculations. Substitution of elements and changes in the lattice structure have been shown to impact the electronic and phonon spectra of these compounds.