Prediction of Thermoelectric Properties of PtSnX (X = Ti, Zr) Based on First-Principles Calculations

In this study, the thermoelectric transport properties of PtSnTi and PtSnZr are systematically investigated using advanced computational methods, including self-consistent phonon (SCP) theory, compressed sensing (CS) techniques, and the Boltzmann transport equation (BTE). The lattice thermal conductivity (κ_L) is accurately determined by combining three-phonon and four-phonon scattering processes. In addition, the Grüneisen parameter, phonon scattering rate, and available phase space are analyzed in detail. The significant reduction of κ_L is attributed to an anomalous dithering (rattling) effect, which originates from the weakening of the Pt–Sn bond and leads to the enhancement of noncovalent interactions. In the electronic transport analysis, five main scattering mechanisms are considered: anisotropic acoustic deformation potential (ADP), polar optical phonons (POP), ionized impurity (IMP), piezoelectric interaction (PIE), and mean free path (MFP) scattering. These mechanisms enable accurate prediction of key electronic transport properties, including electrical conductivity (σ), Seebeck coefficient (S), and power factor (PF). Notably, PtSnZr exhibits a multivalley electronic structure, which enhances the PF and exhibits excellent electrical performance. The calculated maximum dimensionless figure of merit (ZT) values of PtSnTi and PtSnZr reach 0.58 and 0.76 at 800 K, respectively. In summary, this study elucidates the physical mechanisms behind the low lattice thermal conductivity and high power factor in PtSnX (X = Ti, Zr) compounds, providing a theoretical basis for the rational design of high-performance thermoelectric materials.