Thermoelectric transport properties of the van der Waals-type layered rhombohedral SnAs-based compound, EuSn2As2

Abstract The thermoelectric transport properties of the van der Waals-type layered rhombohedral SnAs-based compound, EuSn 2 As 2 , have been investigated. A densified polycrystalline sample of EuSn 2 As 2 with porosity ( ϕ ) of 2.4(9) vol.% exhibited a weak orientation to the c -axis for hexagonal coordination system; the weak orientation is parallel ( P ∥ ) to the pressing direction of hot pressing. Measurements of electrical resistivity ( ρ ), Seebeck coefficient ( S ), and thermal conductivity ( κ ) were conducted perpendicular ( P ⊥ ) to the pressing direction. The experimental values of ρ and S exhibit metallic temperature dependence and p -type carrier polarity. The power factor ( P ) was 0.51(8) mW m −1 K −2 at 673(4) K. Using the Wiedemann–Franz–Lorenz law, the phonon thermal conductivity ( κ ph ) was estimated to be 0.4(6) W m −1 K −1 at 673(6) K. The dimensionless figure of merit, ZT , was 0.092(17) at 673(3) K.