Structural and thermoelectric characterizations of high pressure sintered nanocrystalline Bi2Te3 bulks

Using Bi2Te3 nanopowders prepared from ball milling of elemental Bi and Te, nanocrystalline Bi2Te3 bulks were fabricated with high pressure sintering technique under variable pressures. The structural and thermoelectric properties were characterized, revealing a strong correlation with the sintering pressure. The nanocrystalline Bi2Te3 bulk fabricated under 2 GPa exhibits good thermoelectric properties with ZT over 0.8 from 300 to 460 K and a peak ZT of 1.03 occurring at 403 K, which can be attributed to the small thermal conductivity from enhanced phonon scattering by grain boundaries and defects, as well as to the good electrical property comparable to that of the zone melting material.