Thermoelectric Properties of Zintl Phase Compounds of Ca_1−xEu_xZn₂Sb₂ (0 ≤ x ≤ 1)

p-Type Ca_1−xEu_xZn₂Sb₂ (0 ≤ x ≤ 1) polycrystalline specimens were prepared by direct solid-state reaction of elements followed by appropriate annealing, grinding and spark plasma sintering for densification. The thermoelectric (TE) properties of Zintl phase Ca_1−xEu_xZn₂Sb₂ were investigated by measuring resistivity, Seebeck coefficient and thermal conductivity from 300 K to 720 K. All Eu doped specimens show more than 50% decrease in electrical resistivity, while their Seebeck coefficient value only slightly decrease as compared to CaZn₂Sb₂. Furthermore, a reduction of thermal conductivity was achieved by the additional phonon scatterings of Eu dopants. The cationic substitution of rare earth element Eu in the Ca-site significantly increased the thermoelectric dimensionless figure of merit for all Europium substituted samples. Within this series, EuZn₂Sb₂ shows a good thermoelectric property with a maximum zT value of 0.98 at 720 K.