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a b s t r a c tMagnesium silicide based solid solutions are highly attractive materials for thermoelectric energy harvesting due to their abundance and excellent thermoelectric properties. Identification and testing of suitable contacts is -besides material optimization -the major challenge in the development of thermoelectric modules. We have applied Ni contacts on doped Mg 2 Si samples using a simple one-step sintering technique. These contacts were analyzed by combining microstructural analysis with spatially resolved and temperature dependent contact resistance measurements. We observe very good adhesion, homogeneous and low contact resistances <10 lX cm 2 . as well as good stability with temperature. Three different approaches for determining the contact resistances are compared and the respective errors are discussed.

Solid solutions from magnesium silicide and magnesium stannide exhibit excellent thermoelectric properties due to a favorable electronic band structure and a reduced thermal conductivity compared to the binary compounds. We have optimized the composition Mg2Si0.8Sn0.2 by Sb doping and obtained a thermoelectric figure of merit close to unity. The material comprises of several phases and exhibits intrinsic nanostructuring. Nevertheless, the main features of the electronic transport can be understood within the framework of a single parabolic band model. Compared to Mg2Si we observe a comparable power factor, a drastically reduced thermal conductivity and an increased effective mass.This journal is

Thermoelectric materials can directly convert heat into electrical energy. The characterization of different materials is an important part in thermoelectric materials research to improve their properties. Usually, different methods and setups are combined for the temperature dependent determination of all thermoelectric key quantities - Seebeck coefficient, electrical conductivity, and thermal conductivity. Here, we present a measurement system for the simultaneous determination of all of these quantities plus the direct determination of the figure of merit by means of the Harman method (zT)H in a temperature range from room temperature up to 600 K. A simultaneous measurement saves time and reduces the measurement error, and the change of all material properties can be monitored even for unstable materials. Thermal conductivity measurements are inherently affected by undesired thermal losses, in particular, through radiation at higher temperatures. We show a simple experimental approach to measure radiation losses and correct for those. Comparative measurements on traditional systems show good agreement for all measured quantities.