Impact of microstructure on the thermoelectric properties of the ternary compound Ce3Cu3Sb4

Abstract

We present detailed structural and thermoelectric studies of the ternary compound Ce3Cu3Sb4. This material is of interest due to previously reported considerable thermopower above room temperature (∼ 100μV/K) and low thermal conductivity (2W/(mK)). Here, we present detailed studies concerning microstructural and thermoelectric data, their variation across the samples and possible explanations for the observed behaviour. We have used X-ray diffraction, scanning electron microscopy (SEM), and time-of-flight secondary ion mass spectrometry (TOF-SIMS) for microstructural analysis. The thermoelectric properties were examined using a physical property measurement system (PPMS). We analyse the impact of the sample quality on the thermoelectric properties. The most unstable parameter is the material resistivity which varies between 1.5 and 15mΩcm at room temperature. The properties variability is mainly due to structural defects caused by stresses during material preparation and also due to formation of foreign phases CeCuSb2 and CeSb. The figure of merit ZT is also strongly dependent on the quality of the sample. The largest value ZT ≈ 0.15 at 400K is determined for the almost stoichiometric sample with small amounts of a impurity phases.