Local structure of liquid Te studied by neutron diffraction and EXAFS

Neutron diffraction measurements for liquid (1-) Te have been performed. The first minimum after the first peak of g(r) is well above zero and filled up with temperature, while the second peak diminishes substantially and flattens out at high temperature. The temperature variations of g(r) are analyzed combining the structural information available from our EXAFS results. The curve fitting of g(r) for 1-Te predicts that two different inter-chain components coexist. The first corresponds to the short-distance inter-chain component around 3.2 Å and the second corresponds to the long-distance inter-chain component around 3.8 Å. The filling of the first minimum around 3.2 Å at high temperature is clearly related to the metallization. EXAFS analysis on the basis of the model g(r) indicates that the short-distance inter-chain component (P2) responsible for the metallic conduction in 1-Te as well as the nearest intra-chain component (P1) are required for fitting the oscillatory spectrum in the region of short-range sensitivity of the EXAFS signal. It is concluded that the S-M transition observed for 1-Te arises from the transformation to the densely packed configuration composed of shortened chain molecules.