Cu as an additive in the As0.4Se0.2Te0.4 glass: mean atomic13; volume and Tg

Results of measurements of the mean atomic volume (V) and the glass transition temperature (Tg) for ten glass compositions of the As-Se -Te-Cu system are reported and discussed. The compositions studied can be represented as13; Cux (As 0.4 Se 0.2Teo.4) ioo -x , with the Cu content varying from 5 to 25 atomic percent (at.%.). In the V - x and Tg - x data, changes in slope are observed at the composition with Cu content of 16.67 at.%. A model according to which, with progressive increase in the Cu content, CuAsSe2 and CuAsTe structural units begin to form in place of some of the original As2 Se3 and As2Te3 structural units of the parent glass is able to account for the observed changes in slope at a Cu content of 16.67 at.%