Incorporation of Ag in the crystal lattice of Sb2Te3 creates structural defects that had a strong influence on the transport properties. Single crystals of Sb2−xAgxTe3 (x = 0.0, 0.014, 0.018 and 0.022) were characterized by measurements of the temperature dependence of the electrical resistivity, Hall coefficient, Seebeck coefficient and thermal conductivity at 5 to 300K. With an increasing content of Ag the electrical resistance, the Hall coefficient and the Seebeck coefficient all decrease. This implied that the incorporation of Ag atoms in the Sb2Te3 crystal structure results in an increasing concentration of holes. However, the doping efficiency of Ag appears to be only about 50% of the expected value. This discrepancy was explained by a model based on the interaction of Ag impurity with the native defects in the Sb2−xAgxTe3 crystal lattice. Defects had a particularly strong influence on the thermal conductivity. The temperature dependence of the lattice thermal conductivity was analyzed within the context of the Debye model. Of the various phonon scattering contributions, the dominant influence of Ag incorporation in the crystal lattice of Sb2Te3 was revealed to be point-defect scattering where both the mass defect and elastic strain play a pivotal role.

Transport Coefficients and Defect Structure of Sb2−xAgxTe3 Single Crystals. P.Loštáka, Č.Drašar, J.Horák, Z.Zhou, J.S.Dyck, C.Uher: Journal of Physics and Chemistry of Solids, 2006, 67[7], 1457-63