in this study, internal friction (IF) measurements in the temperature interval of 20-600 degrees C are investigated for p-PbTe and n-PbTe:Cr crystals with the use of a torsion pendulum at low frequencies such as 1 Hz. The corresponding processes of diffusion of oscillation energy are characterized by values of activation energy and frequency factor. We consider that relaxation processes of IF may be the result of the dislocations that slip on the different planes. The influence of chromium doping to PbTe causes the creation of additional barriers with the oscillation of dislocations and increment of cohesion forces within the nuclei of the dislocations. The latter significantly influences the increase of shear modulus from 1.3 x 10(4)N/m(2) for pure PbTe to 3.14 x 10(4) N/m(2) for Cr-doped PbTe. Moreover, IF exhibits different characters in different temperature intervals. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.