Thermal conductivity, thermoelectric power and Mössbauer investigations on atiferromagnetic CeFe1.7Ir0.3Al10

CeFe2Al10 is known to exhibit a Kondo semiconducting behavior without any signature of long range magnetic ordering. A partial Ir substitution for Fe in CeFe2Al10 is found to drive the system towards long range magnetic ordering, and a 15% Ir substitution is found to result in an antiferromagnetically ordered state below 3.1(2) K in CeFe1.7Ir0.3Al10. We present the results of the electrical resistivity ρ, thermal conductivity κ and thermoelectric power S measurements as a function of temperature T, and 57Fe Mössbauer spectroscopy on polycrystalline CeFe1.7Ir0.3Al10. The ρ(T) exhibits Kondo lattice behavior and presents evidence for the formation of a superzone gap in antiferromagnetic state. We estimate Kondo temperature TK≈18 K. The κ(T) does not show any anomaly and reflects a phonon dominated thermal transport. The Lorenz number L(T)=κ(T)ρ(T)/T is found to be much larger than the theoretical Sommerfeld value L0 which also reflects a phonon dominance. The S(T) exhibits a minimum at low T (Smin≈−2.3μV/K, TSmin≈30 K) and a maximum at high T (Smax≈5.4μV/K, TSmax≈225 K). The S(T) data are described by a two-band model with contributions from two Lorentzian shaped f-bands. From the analysis of S(T), we infer that while one of the contributing f-band lies 22 K below the Fermi energy EF, the other one is at 190 K above EF. The 57Fe Mössbauer spectra collected in zero field do not show clear evidence of magnetic ordering, however, the Mössbauer measurements in external fields support an antiferromagnetic ordering in CeFe1.7Ir0.3Al10.