• Cherifi, Fatiha
• Meghoufel, Zahira Faiza
• Menad, Abdelkader
• Kara, Ilham

Abstract

<jats:title>Abstract</jats:title><jats:p>Structural, electronic and thermoelectric properties of LiAuTe ternary compound are studied using density functional theory (DFT) and semi-classical Boltzmann transport theory. The cubic <jats:inline-formula><jats:tex-math> <?CDATA $ $?> </jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi>α</mml:mi></mml:math><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="psac76eeieqn1.gif" xlink:type="simple" /></jats:inline-formula>-phase (space group F<jats:inline-formula><jats:tex-math> <?CDATA ${4}\,$?> </jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mover accent="true"><mml:mn>4</mml:mn><mml:mo stretchy="true">¯</mml:mo></mml:mover><mml:mspace width="0.25em" /></mml:math><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="psac76eeieqn2.gif" xlink:type="simple" /></jats:inline-formula>3m) is predicted to be ground state structure with a significant energy difference compared to honeycomb structure (space group P6<jats:sub>3</jats:sub>mmc). The mechanical and dynamical stability of the <jats:inline-formula><jats:tex-math> <?CDATA $ $?> </jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi>α</mml:mi></mml:math><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="psac76eeieqn3.gif" xlink:type="simple" /></jats:inline-formula>-phase is confirmed by calculating the elastic constants and phonon dispersion frequencies. At equilibrium lattice, with and without spin–orbit coupling, the LiAuTe compound band structure calculations show an s-p band inversion at Γ point, leading to a topological nontrivial semimetal phase. Thermoelectric parameters, such as Seebeck coefficient (<jats:italic>S</jats:italic>), electrical conductivity (<jats:italic>σ</jats:italic>), electronic (<jats:italic>κ</jats:italic><jats:sub><jats:italic>e</jats:italic></jats:sub>) and lattice (<jats:italic>κ</jats:italic><jats:sub><jats:italic>L</jats:italic></jats:sub>) thermal conductivities are computed. Electrons and holes relaxation times (<jats:italic>τ</jats:italic>) are also predicted. Hence, LiAuTe compound exhibits a low <jats:italic>κ</jats:italic><jats:sub><jats:italic>L</jats:italic></jats:sub> value of 1.76 W mK<jats:sup>−1</jats:sup> at room temperature which decreases with temperature increasing. At 900 K, <jats:italic>κ</jats:italic><jats:sub><jats:italic>L</jats:italic></jats:sub> falls to 0.58 W mK<jats:sup>−1</jats:sup> leading to a maximum ZT value of 0.52 at optimized <jats:italic>n</jats:italic>-doping concentration of 2.5 × 10<jats:sup>20</jats:sup> cm<jats:sup>−3</jats:sup>. The present study reveals that LiAuTe compound is a suitable candidate for thermoelectric applications and will open new horizons for further researches on similar types of topological thermoelectric materials with better ZT.</jats:p>

Topics

• density
• impedance spectroscopy
• dispersion
• compound
• phase
• theory
• density functional theory
• electrical conductivity
• band structure
• metal-matrix composite
• space group