NMR Studies of the System B-S-Tl

H. Eckert, W. Müller-Warmuth, W. Hamann and B. Krebs

Abstract

11B, 203Tl and 205Tl NMR studies of glasses in the system Tl2SB2S3 have shown striking similarities to borate glasses. For low thallium contents, the fraction N4 of four-coordinated boron atoms increases in proportion to R = mol.% Tl2S/mol.% B2S3, and the monovalent thallium is tetrahedrally coordinated by sulfur. N4 reaches a maximum near R = 0.5, and discontinuous changes of the thallium bonding state towards more covalency is indicated at high Tl contents. Detailed information about the structural units and the precipitation of crystalline phases is obtained from the NMR and X-ray data. Differences between oxide and non-oxide systems are discussed.