Microwave-assisted rapid synthesis of Sb2Te3 nanosheets and thermoelectric properties of bulk samples prepared by spark plasma sintering

Sb2Te3 single-crystalline nanosheets having edge lengths of 300–500 nm and thicknesses of 50–70 nm were rapidly synthesized by a microwave-assisted method using SbCl3, Na2TeO3 and hydrazine hydrate in ethylene glycol at 200 °C for 15 min, and the reaction mechanism was proposed. The bulk sample of Sb2Te3 nanosheets was prepared by spark plasma sintering (SPS), and it still consisted of Sb2Te3 nanosheets after SPS and thermoelectric property measurements. High electrical conductivity σ (2.49 × 104 Ω−1 m−1), high Seebeck coefficient S (210 μV K−1) and low thermal conductivity κ (0.76 W m−1 K−1) at 420 K were achieved. The ZT value was reported for the first time for the Sb2Te3 sintered bulk sample prepared from nanosheet powder, and a relatively high ZT of 0.58 at 420 K was obtained. It is very difficult to achieve high electrical conductivity σ without obvious growth of nanocrystals after sintering, and herein we have made a successful attempt.