Under ambient conditions, arsenic telluride (As₂Te₃) adopts a monoclinic structure (α phase with space group (S.G.)  C2/m). This crystal structure is different from the rhombohedral R-3m structure of α-X₂Te₃ (X= Sb, Bi), commonly known as good thermoelectric materials and more recently, as topological insulators (TIs). However, it is known that under high-pressure (HP) and high-temperature conditions α-As2Te3 transforms into the rhombohedral structure (β phase with S.G. R-3m), isostructural to α-X₂Te₃ (X=Sb, Bi). β-As₂Te₃ can also be obtained by quenching from melted α-As2Te3 sample and it is known to display a good thermoelectric performance upon Sn doping. Therefore, it is no surprise that β-As₂Te₃ was recently proposed to also harbor topological surface states.

The hexagonal unit cell of β-As₂Te₃ contains three quintuple layer (QL) atomic blocks (Te1–As–Te2–As–Te1) linked by van der Waals bonds, as in a-X₂Te₃ (X=Sb, Bi)  . Since the strength of the spin-orbit coupling is lower in β-As₂Te₃ than in a-X₂Te₃ (X=Sb, Bi) due to the lighter mass of As, the transition from a trivial band insulator to a TI requires HP in β-As₂Te₃. According to this, a theoretical study shows that uniaxial strain could cause a quantum phase transition (PT) from a band insulator to a TI state in β-As₂Te₃  at 1.8 GPa.

α-As2Te3 has a lower thermoelectric figure of merit than a-X₂Te₃ (X=Sb, Bi) at room pressure. However, a study of α-As2Te3 under uniaxial stress has revealed a pressure induced structural PT from monoclinic (α-As2Te3) to rhombohedral structure (β-As2Te3) near 7.0 GPa, leading to a dramatic enhancement in its thermoelectric properties. In this context, it is important to understand the behavior of pure β-As2Te3 under hydrostatic pressure before investigating the thermoelectric properties of β-As2Te3 with dopants. A close comparison of the energy bands of b-As₂Te₃ with energy bands of α-Bi₂Te₃ shows that the band structures are quite similar. This indicates that β-As2Te3 may have good thermoelectric properties.

All the studies previously mentioned point to the fact that it is necessary to perform further HP investigations with b-As₂Te₃ without considering uniaxial strain in order to explore the evolution of phase b under hydrostatic pressure. With this purpose, we have successfully synthetized β-As₂Te₃, with a high degree of purity by using a Paris-Edinburg cell, and carried out in-situ angle-dispersive X-ray diffraction and Raman spectroscopy measurements as well as first principles calculations at HP. Our simulations and measurements have allowed us to characterize the structural and vibrational behavior of b-As₂Te₃ under hydrostatic pressure. In particular, our electronic band structure calculations have been crucial to shed light on the possible TI state and to explore the improvement of thermoelectric power of b-As₂Te₃ ,since it is well known that the valence and conduction bands closest to the Fermi level exhibit multiple valleys in narrow gap semiconductors.