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H. Hoshino, A. Endo, K. Maruyama
The Network-Chain Transformation in the Liquid As-Te Mixtures near the Semiconductor-Metal Transition
The results of neutron diffraction and EXAFS measurements for l-Te and l-As-Te mixtures (10, 20, 30 and 40at. As) are discussed. The g(r) patterns of l-Te show a substantial overlap between the first and second peaks. The first minimum after the first peak of g(r) around 3.2Å is filled up at high temperature. Upon the addition of As to l-Te the first peak of g(r) becomes sharp, implying that As atoms bridge between Te chains and suppress the thermal fluctuations of the inter-chain distances. The filling of the first minimum around 3.2Å observed for l-As-Te mixtures at high temperature is associated with the inter-chain correlation in a densely packed configuration. From the EXAFS analysis of l-As-Te mixtures we conclude that the network structure composed of threefold coordinated As atoms and twofold coordinated Te atoms is transformed into a twofold coordinated chain structure. The network-chain transformation is accompanied by a gradual semiconductor to metal transition. The first sharp diffraction peak observed for l-As20Te80 and l-As40Te60 is related to the Te-Te intermediate range order in -Te-As-Te- or -Te-As-As-Te- chain molecules.
Zeitschrift für Physikalische Chemie, Oldenbourg Wissenschaftsverlag
Print ISSN: 0942-9352
Volume: 217, 07/2003
Pages: 847