HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

No abstract

Density functional (DFT) theory and semiclassical Boltzmann theory are used to calculate structural, mechanical, electronic, and transport properties of RuVAs and RuNbAs half‐Heusler alloys. The band structure calculations reveal a p‐type semiconducting state with narrow indirect (L–X) gap values of 0.20 and 0.36 eV for RuVAs and RuNbAs alloys, respectively. The Seebeck coefficient S, electrical conductivity σ, thermal conductivity κe, and figure of merit ZT are calculated in the temperature range 100–1200 K. The lattice thermal conductivity κL and the relaxation time τ are also determined. At room temperature, RuVAs and RuNbAs alloys exhibit ZT values of 0.22 and 0.30 respectively, which correspond to the lattice thermal conductivity κL equal to 18.67 and 15.14 W m−1 K. κL rapidly decreases with increasing temperature. In addition, the maximum value of ZT reaches 0.47 at 900 K and 0.62 at 1000 K for RuVAs and RuNbAs alloys, respectively. Consequently, these compounds could be a candidate for use as p‐type thermoelectric materials operating at high temperatures.

No abstract

Structural, electronic and thermoelectric properties of LiAuTe ternary compound are studied using density functional theory (DFT) and semi-classical Boltzmann transport theory. The cubic α -phase (space group F 4 ¯ 3m) is predicted to be ground state structure with a significant energy difference compared to honeycomb structure (space group P63mmc). The mechanical and dynamical stability of the α -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 (S), electrical conductivity (σ), electronic (κ e ) and lattice (κ L ) thermal conductivities are computed. Electrons and holes relaxation times (τ) are also predicted. Hence, LiAuTe compound exhibits a low κ L value of 1.76 W mK−1 at room temperature which decreases with temperature increasing. At 900 K, κ L falls to 0.58 W mK−1 leading to a maximum ZT value of 0.52 at optimized n-doping concentration of 2.5 × 1020 cm−3. 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.