On the structural, electronic, and thermoelectric properties of EuMg${}_2$X${}_2$ (X = P, As, Sb, Bi) zintl phase; A first principles investigations

The key solution to the now-a-days energy crisis is the conversion of waste heat into useful electrical energy. In this work, the structural, electronic, and thermoelectric characteristics of EuMg${}_2$X${}_2$ (X = P, As, Sb, Bi) zintl materials have been investigated comprehensively through first principles studies. Structural analysis shows that our measured values fit well with the previous available experimental data. Three potential functionals, PBE GGA, TB-mBJ, and hybrid functional (YS-PBE0), have been used to study the electronic behavior of the titled compounds. EuMg${}_2$X${}_2$ (X = P, As, Sb, Bi) reveal band gaps of 0.83 eV, 0.72 eV, 0.34 eV, and 0.41 eV, respectively, through hybrid functional (YS-PBE0). Density of states (DOS) and partial density of states (PDOS) studies reveals the role offered by different atomic orbitals in the formation of electronic band structures of the samples. Similarly, thermoelectric tone of the said compounds is calculated by virtue of BoltzTraP2 computational code. The ultralow thermal conductivity and optimum level of carriers' concentration encompass these materials to be good thermoelectrics with better and reasonable thermoelectric efficiency (ZTe).