Fig. 5. R(T) curves for Pb_1-xSn_xTe_0.95S_0.05 samples. 1 - x=0.023, 2 - x=0.046, 3 - x=0.118, 4 - x=0.248, 5 - x=0.358, 6 - x=0.629. Curves 2, 3, 4, 5 are shifted up by 10, 20, 25 and 20 units, respectively. Samples 1-3 are of n-type, 4-6 - of p-type. Arrows indicate the direction of temperature change during recording the curves. The insert shows the dependence of T_c on tin concentration.