Short range order in amorphous and liquid Se 1−xTe x systems

Abstract

In this paper we present a study of local order in amorphous and liquid SeTe systems. The first part is a neutron scattering study of the Selenium in the amorphous state at room temperature and in the liquid state from the melting point up to 900 C. The Se 1−xTe x mixtures are studied in the amorphous state up to 40% atomic Tellurium and in the liquid state up to 100% Tellurium. The pair correlation function clearly emphasizes the importance of the covalent bonding the divalence of the Selenium and the very sharp 1st and 2nd peaks even at high temperatures and up to 50% Tellurium. Hence in the second part we deal with a quasi-crystalline model already used for the liquid Selenium up to 900 C. A generalization of this calculation to binary systems provides us with a fair simulation of amorphous and liquid Se 1−xTe x systems structure factors. For the lowest concentrations in Tellurium the short range order seems to be mainly substitutional, as far as the Selenium chains are concerned. By increasing the Tellurium concentration the 3-valency of Tellurium in the liquid state produces a chain branching which distorts the Selenium-like structure.