Elastic, electronic, optical and thermodynamic properties of Ba3Ca2Si2N6 semiconductor: First-principles predictions

Abstract

In this paper, we present and discuss the results of first-principles calculations of the structural, electronic, optical, elastic and thermodynamic properties of the monoclinic quaternary nitride Ba<inf>3</inf>Ca<inf>2</inf>Si<inf>2</inf>N<inf>6</inf>. A comparison between the computed crystal structure parameters and the corresponding experimental counterparts shows a very good agreement between them. The elastic constants were evaluated numerically for the monocrystalline and polycrystalline Ba<inf>3</inf>Ca<inf>2</inf>Si<inf>2</inf>N<inf>6</inf> using the strain–stress approach. The predicted elastic constants demonstrate that Ba<inf>3</inf>Ca<inf>2</inf>Si<inf>2</inf>N<inf>6</inf> is soft, ductile and mechanically stable. Ba<inf>3</inf>Ca<inf>2</inf>Si<inf>2</inf>N<inf>6</inf> shows a strong anisotropic behavior of the elastic and structural properties. The calculated band structure reveals a semiconductor character of Ba<inf>3</inf>Ca<inf>2</inf>Si<inf>2</inf>N<inf>6</inf>. The spectra of the macroscopic linear optical functions, namely the complex dielectric function, reflection coefficient, energy loss of electrons, absorption coefficient and complex refractive index, were calculated and discussed. The quasi-harmonic Debye model was used to explore the temperature and pressure dependencies of certain macroscopic physical parameters for Ba<inf>3</inf>Ca<inf>2</inf>Si<inf>2</inf>N<inf>6</inf>. © 2020 Elsevier B.V., All rights reserved.