Structural studies of AgSbTe2 under pressure: Experimental and theoretical analyses

The crystal structure of AgSbTe₂ has been refined using first-principles calculations, from which the ordering of the cations, Ag and Sb, was confirmed. The spontaneous formation of two (D4 and L1₁) phases at ambient and elevated pressure was demonstrated theoretically. The compound was also prepared and its high-pressure structural deformation sequence, ranging from ambient to 50.9 GPa, was observed with synchrotron radiation at room temperature. The compound underwent a pressure-induced amorphization (PIA) at 24.6 GPa and then started recrystallizing at 49.2 GPa. The bulk modulus (B₀) and pressure derivative of the bulk modulus (B_p) were determined experimentally to be 56.3 ± 5.1 GPa and 4.3 ± 0.8, respectively. We suggest that large displacements of Te atoms to Ag vacancy positions are responsible for PIA and the recrystallization.