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Abstract:
The thermoelectric properties of the intermetallic semiconductor RuGa3
are investigated. Large single crystals were grown to study intrinsic
properties. To investigate the influence of grain boundaries in this
system, the single crystals were ground to powder and densified using
spark plasma sintering treatment. The initial chemical composition is
maintained with the introduction of grain boundaries. Electrical
resistivity data show semiconducting behavior for single- and
polycrystalline samples. The high thermal conductivity (>500 W K-1
m(-1)) obtained for single crystals at low temperatures is reduced by a
factor of 10 in the polycrystalline specimen. The thermopower shows a
change between n-type and p-type behavior with a sharp minimum of about
-700 mu V K-1 at 38 K for single crystals, which is completely
suppressed by the introduction of grain boundaries. A comparison with
RuIn3 shows the potential of RuGa3 as a thermoelectric material in its
single- and polycrystalline form. (C) 2014 Elsevier Masson SAS. All
rights reserved.
