Low-temperature transport and thermodynamic properties of dense Kondo alloys Ce8Pd24(Al1−xSnx)

The alloys Ce8Pd24(Al1−xSnx) with 0≤x≤1 were studied by means of electrical resistivity, thermal conductivity, thermoelectric power, magnetic susceptibility and magnetization measurements. In the entire composition range, an antiferromagnetic (AFM) long-range ordering has been established at low temperatures, with the Néel temperature increasing linearly from TN = 4.3 K for Ce8Pd24Al to TN = 7 K for Ce8Pd24Sn. Below TN, the electrical resistivity is dominated by scattering conduction electrons on spin-wave excitations. In the paramagnetic state, the electrical transport in the alloys with 0≤x≤0.7 reveals both coherent Kondo lattice scattering and crystal-electric field (CEF) effect, while that in the alloys with x≥0.8 appears governed by CEF only. Above TN, all the alloys exhibit well localized magnetic behavior due to trivalent Ce ions. At high temperatures, the thermoelectric power can be interpreted in terms of a phenomenological resonance model giving an estimate of the CEF effect. The thermoelectric figure of merit of Al-rich alloys is small compared to those of commercial thermoelectric materials.