Electronic structure and thermoelectric properties of full Heusler compounds CaYZ (Y = Au, Hg; Z = As, Sb, Bi, Sn and Pb).

We investigate the transport properties of bulk CaYZ (Y = Au, Hg; Z = As, Sb, Bi, Sn and Pb) by a combination method of first-principles and Boltzmann transport theory. The focus of this article is the systematic study of the thermoelectric properties under the effect of a spin-orbit coupling. The highest dimensionless figure of merit () of CaAuAs at optimum carrier concentration are 1.23 at 700 K. Interestingly enough, for n-type CaHgPb, the maximum are close to each other from 500 K to 900 K and these values are close to 1, which suggests that semimetallic material can also be used as an excellent candidate for thermoelectric materials. From another viewpoint, at room temperature, the maximum PF for CaYZ are greater than 3 mW m K, which is very close to that of ∼3 mW m K for BiTe and ∼4 mW m K for FeVAl. However, the room temperature theoretical of CaYZ is only about 0.85-1.6 W m K, which is comparing to 1.4 W m K for BiTe and remarkably lower than 28 W m K for FeVAl at same temperature. So CaYZ should be a new type of promising thermoelectric material at room temperature.