Speaker
Description
Tin selenide (SnSe) doped with manganese (Mn) is a promising mid-temperature thermoelectric material owning to its ultralow lattice thermal conductivity and tunable electronic properties. Advances densification techniques such as spark plasma sintering (SPS) impose significant cost and scalability barriers. This study investigates the use of processing aid (PA) agents, ethylene glycol (EG) and stearic acid (SA) to enhance the cold press densification of Sn0.8Mn0.2Se synthesized by wet ball milling. Pellets were compacted at 200, 390, and 618 MPa and subsequently annealed at 450 °C under a nitrogen atmosphere. Structural, microstructural, thermal properties were systematically characterized using XRD, FESEM, EDX and LFA. Results demonstrate that SA at 618 MPa stabilizes the SnSe orthorhombic lattice (Sn:Se = 1.02:1), preserves p-type Seebeck behaviour, and achieves an ultralow thermal conductivity of ~0.15 Wm−1K−1 through extreme grain refinement (~21 nm) and phonon glass-like scattering. In contrast, EG at 390 MPa promotes selenium vacancy formation (VSe), driving strong n-type behaviour with higher thermal conductivity of ~0.5 Wm−1K−1. These findings establish that PA chemistry and compaction pressure are co-determining parameters that govern thermoelectric performance through competing densification and grain engineered mechanisms, offering a cost-effective and scalable fabrication pathway for Sn-based thermoelectric materials.
