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    • Keywords

       

      Be$_x$Mg$_{1−x}$S, Be$_x$Mg$_{1−x}$Se and Be$_x$Mg$_{1−x}$Te alloys; DFT-based FP-LAPW methodology; WC-GGA, mBJ and EV-GGA functional; structural and elastic features; electronic and optical characteristics.

    • Abstract

       

      Structural,mechanical and optoelectronic features of cubic Be$_x$Mg$_{1−x}$S, Be$_x$Mg$_{1−x}$Se and Be$_x$Mg$_{1−x}$Te alloyshave been explored by DFT-based FP-LAPW approach. Nonlinear reduction in lattice constant, but increment in bulk modulus and each of the elastic constants $C_{11}$, $C_{12}$ and $C_{44}$, occurs with increasing Be-concentration $x$ in each system. All the specimens exhibit elastic anisotropy. Specimens at $x = 0.0$, 0.25 and 0.50 show ductility, but remaining specimens at $x = 0.75$ and 1.0 show brittleness. Each ternary alloy is a direct ($\Gamma$−$\Gamma$) band gap ($E_{\rm g}$) semiconductor. Almost linear decrease in $E_{\rm g}$ with increase in $x$ is observed in each alloy system. Ionic bonding exists among the constituents of all specimens. The occupied valence chalcogen-p as initial and unoccupied conduction Be-3s, 2p and Mg-4s, 3p as final states play a keyrole in optical transitions. Nature of variation of zero-frequency limit in each of the $\epsilon_1(\omega)$, $n(\omega)$ and $R(\omega)$ spectra with $x$ isopposite to, while critical point in each of the $\epsilon_2(\omega)$, $k(\omega)$, $\sigma(\omega)$ and $\alpha(\omega)$ spectra with $x$ is similar to, the nature of variation of $E_{\rm g}$ with $x$.

    • Author Affiliations

       

      BIMAL DEBNATH1 MANISH DEBBARMA1 DEBANKITA GHOSH1 SAYANTIKA CHANDA1 RAHUL BHATTACHARJEE1 2 SURYA CHATTOPADHYAYA1

      1. Department of Physics, Tripura University, Suryamaninagar 799022, India
      2. Department of Physics, Women’s College, Agartala 799001, India
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