Metavalent Bonding-Mediated Dual 6s2 Lone Pair Expression Leads to Intrinsic Lattice Shearing in n-Type TlBiSe2

• DOI: 10.1021/jacs.3c02146
• Publication Date: 2023-04-12T12:22:23Z
• Authors: Ivy Maria; Raagya Arora; Moinak Dutta; Subhajit Roychowd...; Umesh V. Waghmare; Kanishka Biswas
• Keywords: Lone pair; Translational symmetry

Metavalent bonding has attracted immense interest owing to its capacity impart a distinct property portfolio materials for advanced functionality. Coupling metavalent lone pair expression can be an innovative way propagate lattice anharmonicity from pair-induced local symmetry-breaking via the soft p-bonding electrons achieve long-range phonon dampening in crystalline solids. Motivated by shared chemical design pool topological quantum and thermoelectrics, we based our studies on three-dimensional (3D) insulator TlBiSe2 that held prospects 6s2 dual-cation investigate if proposed hypothesis deliver novel thermoelectric material. Herein, trace inherent phononic origin of low thermal conductivity n-type dual intrinsic shearing strongly suppresses value 1.1-0.4 Wm-1 K-1 between 300 715 K. Through synchrotron X-ray distribution function first-principles studies, have established exists not monomorphous R-3m structure but as distorted configurations. Via cooperative movement constituent atoms akin transverse mode facilitated TlBiSe2, shuttles various energetically accessible low-symmetry structures. The orbital interactions ensuing multicentric visualized through Wannier functions augment transmission atomic displacement effects TlBiSe2. With additional point-defect scattering, κlatt 0.3 was achieved TlBiSeS with maximum figure merit (zT) ∼0.8 at