Thermoelectrical properties of the compounds ScMVIIISb and YMVIIISb (MVIII = Ni, Pd, Pt)

The research into new materials with good thermoelectric properties has revealed new compounds consisting of metallic elements (Bando Y, Suemitsu T, Takagi K, Tokushima H, Echizen Y, Katoh K, Umeo K, Maeda Y and Takabatake T 2000 J. Alloys Compounds 313 1-6, Ghelani N, Loo S, Chung D, Sportouch S, Nardi S, Kanatzidis M, Hogan T and Nolas G 2000 Mater Res. Soc. 626 Z8.61). The half-Heusler compound ZrNiSn, in particular, shows promising thermoelectric properties and has been studied by many scientists during recent years (Uher C, Hu S, Yang J, Meisner G P and Morelli D T 1997 Proc. ICT'97: 16th Int. Conf. on Thermoelectrics pp 485-8, Romaka L P, Stadnyk Yu V, Goryn A M, Gorelenko Yu K and Skolozdra R V 1997 Proc. ICT'97: 16th Int. Conf. on Thermoelectrics pp 516-19, HOW H, Ramirez A P, Goldmann C, Ernst G, Wolfing B and Bucher E 1998 J. Phys.: Condens. Matter 11 1697-709, Oestreich J, Kafer W, Richardt F, Probst U and Bucher E 1999 Proc. 5th European Workshop on Thermoelectrics pp 192-5): In an effort to find new thermoelectric materials, the half-Heusler compounds of the groups ScM(VIII)Sb and YM(VIII)Sb (M(VIII) = Ni, Pd, Pt) were synthesized by arc melting and the thermoelectric properties were examined by standard characterization methods. Doping experiments showed that it is possible to change the electrical properties of the compounds while retaining the half-Heusler structure. Within the two groups, YPtSb showed the best thermoelectrical properties. At a temperature of 400 K the electrical conductivity of YPtSb is 748 Omega(-1) cm(-1) and the Seebeck coefficient is 116.3 muV K(-1). The thermal conductivity at 400 K extrapolated using the Wiedemann-Franz law is 2.87 W K(-1) m(-1). This leads to a dimensionless figure of merit of 0.14.