... X-ray absorption fine structure studies of the local structure of large Pb and Sn substitutional impurities in GeTe were carried out. ... The off-centering of Pb and Sn impurities is explained by participation of their deeply lying 6s 2 and 5s 2 lone electron pairs in chemical bonding in the condition of strong local stress created by these impurities in the lattice. ... Other works on off-center impurities ...