Cu-Bi-Se-based pavonite homologue: a promising thermoelectric material with low lattice thermal conductivity

摘要

Pavonite homologues, Cu_(x_y)Bi_(5-y)Se8 (1.2 ≤ × 1.5,0.1 ≤ y≤ 0.4), in a polycrystalline bulk form have been synthesized using a conventional solid state sintering technique. Their thermal and electronic transport properties were evaluated for mid-temperature thermoelectric power generation applications. Structural complexity, based on unique substitutional and interstitial Cu atoms in the structure, makes this system attractive as an intrinsic low thermal conductivity material; also the band structure calculations revealed that interstitial Cu atoms generate n-type carrier conduction. Room temperature lattice thermal conductivities ranging between 0.41 W m~(-1) K~(-1) and 0.55 W m~(-1) K~(-1) were found for Cu_(x_y)Bi_(5-y)Se8; these values are comparable to those of the state-of-the-art low lattice thermal conductivity systems. These extremely low thermal conductivities combined with the power factors result in the highest ZT = 0.27 at 560 K for Cu_(1.9Bi_(4.6)Se8.