Concentration Fluctuations Induced by Structural Changes in the Liquid Se--Te Alloy

抄録

New thermodynamic relations are applied to the liquid Se--Te system to investigate the concentration fluctuations induced by the structural change. The excess Darken stability caused by the structural change has been quantitatively evaluated with experimentally available data. It is definitely negative, and the absolute magnitude of which takes a peak in the composition-temperature region where the structural change occurs. The results provide the thermodynamic basis of the segregation tendency in a microscopic scale developed with increasing temperature, which was found with high resolution neutron diffraction experiments nearly two decades ago. Discussion has been made in relation to the intrinsic instability of chain structure of VIb chalcogenide elements which plays a key role to makes the effective interaction between Se--Te pair dependent on composition and temperature.