Isotherms of thermal conductivity in PbTe-MnTe solid solutions

The temperature dependences of the thermal conductivity λ of PbTe-MnTe solid solutions (0–4 mol % MnTe) are measured in the range 170–670 K. The data obtained are used in constructing the isotherms of the lattice thermal conductivity λ_l and in estimating the effective cross section for phonon scattering by Mn impurity atoms. It is found that all the isotherms exhibit an anomalous increase in λ_l in the concentration range 1.25–2.0 mol % MnTe, which disagrees with the usually observed decrease in λ_l with an increase in the impurity concentration. It is assumed that the anomalous increase in λ_l manifests itself after attainment of the percolation threshold when a continuous chain of overlapping deformation fields produced by individual atoms (an infinite cluster) is formed in the crystal. In the crystal lattice, stresses are partly compensated and phonon scattering decreases. The assumption is made that the effect observed has a universal character.