Ab Initio Comparison of Bonding Environments and Threshold Behavior in Ge<inf>x</inf>As<inf>10</inf>Se<inf>90- x</inf> and Ge<inf>x</inf>Sb<inf>10</inf>Se<inf>90- x</inf> Glass Models

Abstract

Ab initio models of Ge<inf>x</inf>As<inf>10</inf>Se<inf>90-x</inf>, and Ge<inf>x</inf>Sb<inf>10</inf>Se<inf>90-x</inf> glasses are constructed, and their bonding environments are characterized and compared against each other and to recent experimental studies of equivalent glasses at the same stoichiometry and density. A minimum in the linear refractive index is found to correlate with a maximum in the number of length-one, predominantly Se, atomic chains for both glass types. The threshold behavior difference between GeAsSe and GeSbSe is shown to be due to the appearance of As-As-Se<inf>2</inf> structural units beyond the MCN = 2.67 threshold in the GeAsSe glasses. Show more