Short and medium range order in Se1-xTex glasses

Complementary XAFS measurements (LURE and NSLS) of Se1-xTex glasses have been carried out on both the Se and Te K-edges at low and room temperatures. Using a multi-shell best fit analysis procedure, we have reconstructed the Se and Te local environment: (i) first shell intrachain nearest neighbors (Se-Se-1, Se-Te-1, Te-Se-1,and Te-Te-1); (ii) second shell intrachain (Se-Se-2 and Se-Te-2) and interchain next nearest neighbors (Se double left right arrow Se-3 single scattering in the chains Se-Se-1-Se-3 and Se-Te-1-Se-3). For the first and second coordination shells we suggest that the intrachain chemical order increases with Te content. On the other hand, we propose a model of random distribution of Se and Te atoms between the chains.