Promising thermoelectric properties of heavy-fermion semimetal Pr₃Os₄Ge₁₃

Here we report the magnetic, electronic and thermal transport properties of the heavy-fermion semimetal Pr3Os4Ge13 with a cage-like structure by means of magnetic susceptibility, χ(T), isothermal magnetization, M(B, T), electrical resistivity, ρ(B, T), Hall coefficient, R H(T), specific heat, C p(T), thermal conductivity, κ(T) and thermoelectric power, S(T). ρ(T) and R H(T) show semimetallic features in a manner that mimics a thermal activated behaviour with an activation energy, Δ/k B = 6.5 K indicating the opening of a small energy gap in the material. At low temperatures, a Sommerfeld coefficient, γ = 128 mJ (mol-1 K-2) observed indicates a mass enhancement of the quasiparticles at low temperatures which bears witness to a heavy fermion state in Pr3Os4Ge13. A Wilson-Sommerfeld ratio, W R and the dimensionless ratio, S/γT of 1.01 and 0.62 0.018 observed, respectively, are in good agreement with the Fermi liquid scenario. S(T) and R H(T) reveal hole dominated transport (p-type material) with a relatively large room temperature value of S(T) = 32.85 0.98 μV K-1. A room temperature low value of κ(T) = 1.61 W K-1 m-1 leads to a thermoelectric figure of merit, ZT = 0.03 0.001 which is comparable to values achieved in several clathrates around the same temperature. Features from S(T) and ρ(T) favour the realization of a higher ZT value at elevated temperatures.