Effects of Pd atom vibration in the Sr–Te octahedral interstitial space in Zintl compound SrPdTe on lattice anharmonicity and thermoelectric properties.

This article investigates the thermoelectric (TE) properties of the Zintl compound SrPdTe through first-principles calculations, focusing on the impact of anharmonic lattice vibrations and phonon scattering on thermal conductivity. The study reveals that the large atomic mean square displacement of Pd atoms, situated between Sr–Te octahedra, leads to strong quartic anharmonic effects and ultralow lattice thermal conductivity (κL), which is further influenced by three- and four-phonon scattering processes and phonon frequency renormalization. Electron transport analysis, including spin–orbit coupling effects, shows multiple near-degenerate valence bands contributing to a high power factor (PF) at elevated temperatures. Combining ultralow κL and high PF, SrPdTe exhibits promising thermoelectric performance with calculated figure of merit (ZT) values reaching 3.24 for p-type and 2.74 for n-type doping at 700 K, suggesting its potential as an efficient thermoelectric material pending further experimental validation.