Synthesis and properties of CaCd2Sb2 and EuCd2Sb2

High density polycrystalline CaCd2Sb2 and EuCd2Sb2 intermetallics are synthesized by Spark Plasma Sintering and their thermoelectric properties are investigated. X-ray diffraction measurements reveal both materials have a structure in R (3) over barm space group, containing a small amount of CdSb as a second phase. Thermoelectric measurements indicate both are p-type conductive materials. The figure of merit value of CaCd2Sb2 is 0.04 at 600 K and that of EuCd2Sb2 is 0.60 at 617 K. Theoretical calculations show that CaCd2Sb2 is a degenerate semiconductor with a band gap of 0.63 eV, while EuCd2Sb2 is metallic with DOS of 13.02 electrons/eV. For deeper understanding of the better thermoelectric properties of EuCd2Sb2, its low temperature magnetic, transport and heat capacity properties are investigated. Its Neel temperature is 7.22 K, convinced by heat capacity anomaly at 7.13 K. Hall effect convinced that it is a p-type conductive material. It has high Hall coefficient, high carrier concentration and high carrier mobility of + 1.426 cm(3)/C, 4.38 x 10(18)/cm(3) and 182.40 cm(2)/Vs, respectively. They are all in the magnitude of good thermoelectric materials. The Eu 4f level around Fermi energy and antiferromagnetic order may count for the better thermoelectric properties of EuCd2Sb2 than that of CaCd2Sb2. (C) 2009 Elsevier Ltd. All rights reserved.