Transport properties of Zintl phase Yb1–xCaxCd2Sb2 at low temperature

We investigated the transport properties of isoelectronic substitution of Yb by Ca for Zintl phase YbCd2Sb2 below 300 K. The p-type Yb1–xCaxCd2Sb2 (0.2≤x≤0.8) samples were synthesized via a solid-state reaction followed by suitable cooling, annealing, grinding, and spark plasma sintering (SPS) densification processes. For samples with x=0.2, 0.4, 0.5, 0.6, 0.8, the electrical conductivity, Seebeck coefficient, thermal conductivity, heat capacity and Hall effect measurements were carried out in the temperature range from 1.9 to 300 K. It was found that the Ca substitution effectively lowered the thermal conductivity at low temperature, while the electrical resistivity and the Seebeck coefficient in the compounds were found to increase with increasing Ca concentration. As a result, the dimensionless figure of merit ZT of 0.18 was attained at 300 K for sample with x=0.2.