Existence of quasi-stable structures in liquid pnictogens proven by Kazan Federal University scientists

The relative positions of atoms in pnictogen melts exhibit universal properties, and quasi-stable structures within them form according to a common pattern. Scientists from the Institute of Physics at Kazan Federal University have demonstrated the existence of quasi-stable structures in liquid pnictogens (arsenic, antimony, and bismuth)—short-lived chains of atoms that make the medium more ordered at the atomic level compared to conventional liquids.

The structure and spatial arrangement of these chains determines the solidification process and, consequently, the resulting solid material. Understanding the structure of pnictogen melts is important for the fabrication of electronic devices based on them.

The research was supported by a grant from the Academy of Sciences of the Republic of Tatarstan; the results appeared in the Journal of Non-Crystalline Solids. The team of authors included three researchers from the Department of Computational Physics: Department Chair, Professor Anatolii Mokshin, Associate Professor Bulat Galimzyanov, and Assistant Professor Artem Tsygankov.

Arsenic, antimony, and bismuth are silvery metals that are widely used as components in the semiconductor industry. Semiconductor crystals based on these substances are created from the liquid phase.

The scientists investigated the structural features of liquid pnictogens using ab initio molecular dynamics simulations and subsequent analysis of the distributions of the crystalline orbital Hamiltonian population in the detected formations. This approach involves numerically solving the Schrödinger equations, which allows for reliable information on the local structure of the substance without the use of complex, expensive experiments.

The authors discovered that quasi-stable structures in liquid pnictogens form according to a common pattern, driven by p-electron orbitals. An analysis of the structure's total energy as a function of size also revealed a decrease in structural stability with increasing size. This result allows these liquids to be considered in terms of two competing processes: crystallization and the thermal motion of atoms, which inhibits crystallization.

Numerical calculations confirmed that liquid pnictogens differ from ordinary liquids in that they possess quasi-stable structures. Understanding the internal processes occurring at the atomic level will enable the creation of compounds with improved electrical properties. Furthermore, these data can assist in selecting a protocol for fabricating compounds with precisely defined characteristics and analyzing them using both experimental and computer simulation methods.

Today, quantum-mechanical molecular dynamics simulations are actively used to determine the structure of both crystalline solids and liquids. However, in the case of liquid pnictogens, the challenge arises of obtaining reliable information about the local structure of melts containing anomalous inclusions. It should be noted that during the work, an original method of time analysis was used, in which quantum-mechanical calculations are accompanied by the interpretation of the detected anomalous formations as carriers of the crystalline phase.

More information:
Atomic bonding in equilibrium single-component melts. The cases of arsenic, antimony and bismuth
www.sciencedirect.com/science/ … ii/S0022309325004077

Provided by Kazan Federal University