Influence of Sn substitution on the thermoelectric properties in YbAl3

The compound YbAl3 exhibits a very high power factor, but also rather a large thermal conductivity, leading to a low figure of merit. The solid solutions YbAl3-xSnx with x = 0, 0.05, 0.10, 0.20, 0.30 and 0.50 were synthesized by high frequency induction melting, spark plasma sintering (SPS) and annealing treatment. The influence of Sn substitution on the thermoelectric properties of YbAl3 was investigated. The carrier concentration increases but the carrier mobility decreases with increasing x. The electrical resistivity of the sample does not increase apparently with increasing Sn content x until 0.10 but increases evidently with further increasing Sn content x. The absolute Seebeck coefficient increases with increasing Sn content x until 0.20 while the thermal conductivity decreases significantly with increasing x. As a result, the figure of merit ZT can be enhanced by the substitution of Sn for Al. The maximum ZT of 0.27 could be obtained in the YbAl2.90Sn0.10 at 300 K, which is larger than 0.18 for the pure YbAl3 or 0.19 for the Sc-doped YbAl3. (C) 2014 Elsevier B. V. All rights reserved.