  The preparation method of thermoelectric PbTe-CdTe semiconductor
nanocomposite in the form of a bulk material doped with Bi, I or Na, intended
for production the mid-temperature thermoelectric energy generators is
presented. The method takes advantage of the extremely low mutual solubility of
both semiconductors, resulting from their different crystal structure, and is
based on a specifically designed Bridgman growth procedure. It is shown that
the formation of zinc-blende crystalline CdTe grains in the rock-salt matrix of
thermoelectric PbTe can be forced during the synthesis of a composite by
introducing Cd in the form of CdTe compound and choosing the growth temperature
above the melting point of PbTe but below the melting point of CdTe. X-ray
diffraction and SEM-EDX spectroscopy analyzes as well as basic electric and
thermoelectric characterization of the nanocomposite samples containing 2, 5
and 10 at. \% of Cd showed that using proposed growth procedure, it is possible
to obtain both n-type (Bi- or I-doped) and p-type (Na-doped) material with
carrier concentration of 1{\div}5 x 10\^{19} cm\^{-3} and uniformly distributed
CdTe grains with a diameter of the order of 100 nm.
