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The Er169(169Tm)emission Mössbauer spectroscopy has evidenced that photoluminescence centers in Er-doped amorphous hydrogenated silicon are [Er–O] clusters. The local environment of the Er3+ ions in the clusters is similar to the Er3+ environment in Er2O3.

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The influence of the crystal‐to‐glass transition on the local structure in semiconducting compounds and alloys such as As2S3, As2Se3, As2Te3, AsSI, AsSeI, As4Te5I2, As2Se3 · As2Te3, Ge15Te85, and As4Ge15Te81 is analysed by Mössbauer spectroscopy for nuclei of 125Te, 127I, 129Te(129I), and 119Sn and by measuring the chemical shift of the AsLα1 line. It is shown that for such compounds and alloys as As2Te3, As4Te5I2, Ge15Te85, As4Ge15Te81 the transition into the glassy state may take place only under conditions of severe quenching. For such semiconductors the crystal‐to‐glass transition is accompanied by a change in the symmetry of the local environment of the tellurium, iodine, and germanium atoms. A correlation between the change in the electric conductivity and density and the change in the local structure at the crystal‐to‐glass transition is observed.

The effective atomic charges for all sites of the RBa2Cu 0 7 lattices have been found using our Mossbauer data with the G7C~~("Zn) ,"':j Ba('"'CCs), 'n EufS5Gd) isotopes, our calculations of the lattice electric field gradient (EFG) at the lattice sitcs, as wcll as the I7O NMR data available in literature. The charges show holes placed in the chain oxygen sublattice mainly. The CuZf Sternheimer factor has been estimated and the Cu'+ valence EFG in YBa2Cib07 has been found. The zaxes of the total, lattice, and valence EFG tensors for Cii(2) coincide with the crystal axis c. For Cu(1) they coincide with the axes b, a, and a, respectively. a p H n b I aTOMOB BO BCeX Y n a X PeLUeTOK RBaZCu307 H?&eHbI C llOMOqbH) HaLUIIXMeCC-6ay3pOBCKkiX AaHHbIX H a C L I (~~Z~) ,133 BEL('~~CS), EU('"%~), HaIIIIIX BhIYliCJIeHHII~ peIIIe-Toworo r p a n H e H T a s n e~~p u s e c~o r o nonrr (r'3l-I) B ymax, u n w~e p a~y p~b i x HaHHbix no 5IKP H a 1 7 0 . ~T E 3aprrnb1 c o o T s e T m y m T AbIpKe, H a x o n a q e i r c r r npemyqecmemro B n o n p e m e T K e qenoseworo K n c n o p o n a . A a H a oqema + a K T o p a Uhepmaihepa nna Cu2+. H a W e H B a n e m -l3l-I cosnaxawr c K p u c T a n n o r p a @ , l i q e c K o i i ocblo c, a ~n n Cu(1) c o 4 a~u b, a, H a, c o o T B e T c T -Hbl# r3l-I HJIR CU2+ B YBazCu307. mn cU(2) 2-OCU IIOnHOrO, P e l I l e T O s H O r O II BaJIeHTHOrO BeHHO.