Mössbauer Studies on the Tellurium-Selenium Mixed Chains

125 Te Mossbauer absorption measurements have been carried out for Te-Se mixed chains confined in the one-dimensional channels of mordenite crystals as well as for the mixed chains in trigonal crystalline and amorphous phases. 129 I Mossbauer emission spectra have been also taken for 129 Te labeled amorphous and trigonal Te-Se mixtures. The quadrupole splitting at the 125 Te atom is found to be appreciably larger for the isolated chains than for the trigonal mixtures, suggesting that the anisotropy of Te bonding is increased by reducirng the interchain coupling between the adjacent chains. Both 125 Te and 129 I Mossbauer results indicate that the molecular character is much stronger in the amorphous phase than in the trigonal phase.