Low-temperature transportproperties of alpha- and beta-Zn4Sb3 compounds preparedby a gradient freeze and a spark plasma sintering methods


T. Souma, G.Nakamoto, M. Kurisu


 Japan Advanced Institute of Science andTechnology, Tatsunokuchi, Ishikawa 923-1292, Japan


We have prepared two types of Zn4Sb3bulk samples using a gradient freeze (GF) and a spark plasma sintering (SPS)methods to investigate their transport properties below 300 K. From the XRDmeasurement, both samples have been found to be single phase and to possesshigh densities more than 95% of the theoretical one. The measurements ofthermoelectric power, electrical resistivity and magnetic susceptibility forboth the samples have been performed in the temperature range of 5 to 300 K.Both dilatometric and Hall effect measurements have been also done from 78 to300 K. The anomalies associated with the structural phase transition from thebeta- to alpha-phase are observed in these physical quantities at 257.4 K forGF and 236.5 K for SPS samples. The hole concentration for the GF sample isdecreased to one-tenth by the phase transition from the beta- to alpha-phase,whereas for the SPS sample it is not decreased largely. The EPMA measurementshows that the GF sample has higher Zn concentration than the SPS sample. Theseresults suggest that the transport properties of the alpha-Zn4Sb3are strongly dependent on both the chemical composition and sample processing.