Microwave-assisted rapid synthesis of Sb2Te3nanosheets and thermoelectric properties of bulk samples prepared by spark plasma sintering

Abstract

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.