Local Order in Molten Sesub(1-X)Tesub(X)

摘要

In this paper a study of the short range order and of the coordination number in liquid Selenium-Tellurium systems is presented. The first part deals with neutron diffraction measurements of the structure factors of liquid Sesub(1-x)Tesub(x) in the whole concentration range, at 475 C, performed at EL3 reactor in Saclay using a 640 cell multidetector. From these data the radial distribution functions have been calculated. In a second part a structural model based on random chains for Selenium and on a quasicrystalline behavior of Tellurium is presented. For Se-rich melts it is assumed that Tellurium enters the Selenium chains by substitution. In the Te-rich range it is assumed that the local order is represented by substituted SeTe chains in a Tellurium matrix. This model provides with a good representation of the various structure factors. Moreover the coordination number for each concentration in the model has been calculated and the results are consistent with the experimental data. The 2 fold coordination of Se and the 3 valency of Te in the liquid state are emphasized and they can be associated with the metallisation of liquid Tellurium whereas Selenium remains a semiconductor. (Atomindex citation 11:553549)