Thermoelectric properties of Ca1−xSrxRuO3 compounds prepared by spark plasma sintering

Single phase Ca1−xSrxRuO3 (x = 0–1.0) powders were synthesized by a solid-state reaction and compacted by spark plasma sintering. The a-length of the lattice parameter showed a slight minimum around x = 0.6, whereas the b-length, c-length and the unit cell volume increased continuously with increasing x from 0 to 1.0, indicating a solid solution in the whole range. The relative density of Ca1−xSrxRuO3 compacted bodies increased from 75 to 95% with increasing x from 0 to 1.0. The electrical conductivity (σ) at x = 0.1–0.9 was higher than those of the end members (CaRuO3 and SrRuO3) except for that at x = 0.5, and showed metallic conduction at all compositions. The Seebeck coefficient (S) was 30–40 μV K−1, almost independent of composition and temperature. The thermal conductivity (κ) was 2–3 W m−1 K−1 at room temperature and increased with increasing temperature. The κ showed the lowest values at x = 0.2 in the whole temperature range. The dimensionless figure-of-merit (ZT) at x = 0.1–0.9 was higher than those of the end members. The highest ZT was 0.07 at x = 0.2 and 600 K.

► A series of (Ca,Sr)RuO3 solid solution was first prepared by spark plasma sintering. ► Effect of composition of (Ca,Sr)RuO3 solid solution on thermal conductivity and dimensionless figure-of-merit was first investigated. ► Effect of porosity on the electrical conductivity and thermal conductivity has been compensated by Maxwell–Eucken's equation.