MOSSBAUR SPECTROSCOPY OF TIN-119 AND TELLURIUM-125 OF TERNARY COMPOUNDS OF THE SYSTEM THALLIUM-TIN-TELLURIUM

The three compounds Tl2SnTe5, Tl2SnTe3, and Tl4SnTe3 in the thallium-tin-tellurium system have been isolated. The crystal structure of Tl4SnTe3 is not known. The electronic local order around tin and tellurium has been characterized by means of Mossbauer spectroscopy (Sn-119 and Te-125). According the crystal structure of Tl2SnTe5 and Tl2SnTe3, the Mossbauer data are discussed in terms of covalent bonding, both tin or tellurium. The crystal structure of Tl2SnTe5 can be described by the chains [Sn2Te(2)(2)Te(1)(8)](n). The Te(1) and Te(2) atoms have different behavior. For Tl2SnTe3, the crystal structure can be characterized by[Sn2Te8] and Te atoms behave as tellurium and Te(1) of Tl2SnTe5. For these two compounds, Sn atoms are as Sn alpha. For Tl4SnTe3, the ionic character of the Sn-Te bond is enhanced and the isomer shifts and quadrupole splittings of Sn-119 and Te-125 show the two oxidation state for tin(+2) and tellurium(-2). (C) 1994 Academic Press, Inc.