Abstract
We report the results of pressure-induced semiconductor-metal phase transition of the semiconducting chalcogenide compound KPSe6 under high pressure using the ab initio methods. The ground-state energy calculations were performed within density functional theory and the generalized gradient approximation using the pseudopotential method with plane-wave basis sets. The projector augmented-wave (PAW) pseudopotentials were used in our calculation. The optimized lattice parameters were found from total energy calculations as 13 Bohr, 1.6 Bohr, and 1.8 Bohr for cell dimensions one, two, and three, respectively, which are in good agreement with experimental calculations. At zero pressure, the material portrayed a semiconducting property with a direct bandgap of ≈1.7 eV. As we subjected the material to pressure, the band gap was observed to reduce until it disappeared. The phase transition from the semiconductor to metal was found to occur at ∼45 GPa, implying that the material underwent metallization as pressure was increased further.
Highlights
In the recent past, research on the effect of pressure on structural phase transformations and characteristics of materials by calculations from first principles have attracted much attention since they give an insight into the nature of solid-state theories [1, 2], and assist in determining values of essential parameters for industrial applications [3]
When a material is subjected to compressional forces, its electronic band structure changes [10, 11] which further results in a change in its structural properties [10, 12,13,14]. is often leads first to the formation of low-symmetry complex structures which at higher pressure transform into high-symmetry close-packed structures [6, 8, 13]
K 2(s) P 2(p) Se 2(p) functional, the generalized gradient approximation of Perdew–Burke–Ernzerhof [34,35,36] based on Plane Wave self-consistent field (PWscf ) and Ultrasoft pseudopotential (USPP) method
Summary
Research on the effect of pressure on structural phase transformations and characteristics of materials by calculations from first principles have attracted much attention since they give an insight into the nature of solid-state theories [1, 2], and assist in determining values of essential parameters for industrial applications [3]. The delocalization of bonding electrons under pressure reduces the differences between the chemical properties of the elements and their crystal structures [15]. CaS, CaSe, and CaTe alkaline-earth chalcogenides undergo a structural phase transition at a pressure of 40 GPa, 38 GPa, and 33 GPa, respectively [9, 14]. Subjecting a material to high pressure leads to a reduction of interatomic spacing which in turn affects the crystal structure and electronic orbitals [1, 18,19,20,21,22,23]. High pressure can result in the formation of new material with different features from the initial material [24]. Chalcogenide glasses are based on selenium, tellurium, and the addition of other elements such as arsenic, germanium, antimony, gallium, and potassium [3, 25]. ey are well known for their advantages, such as a wide transmittance range (1–12 μm) [3], low intrinsic losses in the mid-IR [26], low phonon energy [27], and the absence of free-carrier
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