Double crystal topographic investigations of PbTe grown by the travelling heater method (THM)
b'THM-grown PbTe and PbTe: Tl were examined near the (n, - n)-position by means of X-ray double crystal arrangement. The half-width of the rocking curves of Tl doped PbTe is larger than that of undoped PbTe by factor two. Long range and local lattice plane distortions, as well as disturbances induced during preparation, in the from of dislocation slip lines and greatly disoriented areas were observed.'