Effect of annealing treatment on thermoelectric properties of n-type Bi-Te-Se sintered materials

In this study, n-type Bi-Te-Se crystals were prepared by the zone melting (ZM) method and bulk materials with high bending strength were fabricated by ZM followed by spark plasma sintering (SPS) technique. The annealing treatment was then carried out at 593 K with holding time of 36 hr for the sintered materials. Thermoelectric properties, including Seebeck coefficient (alpha), electrical conductivity (sigma) and thermal conductivity (kappa) were measured in the temperature range of 300-500 K. The results showed the maximum figure of merit (ZT = alpha²sigmaT/kappa) of 0.79 was obtained for the n-type Bi-Te-Se material through the annealing treatment, which was very close to that of the zone-melted crystal.