Macroscopic thermoelectric inhomogeneities in (AgSbTe2)x(PbTe)1-x -: art. no. 171903

Exceptionally high thermoelectric figure of merit (zT>2), has been reported for (Ag1-ySbTe2)(0.05)(PbTe)(0.95), which may involve the nanoscale microstructure. However, conflicting reports on the same materials claim only zT of 1 or less. Here we show that (Ag1-ySbTe2)(0.05)(PbTe)(0.95) materials are multiphase on the scale of millimeters despite appearing homogeneous by x-ray diffraction and routine electron microscopy. Using a scanning Seebeck microprobe, we find significant variation of Seebeck coefficient (including both n-type and p-type behavior in the same sample) that can explain the discrepancy in reported zT. More homogeneous samples can be prepared with faster cooling rates. (C) 2005 American Institute of Physics.