Rigidity transitions and molecular structure of AsxSe1Àx glasses
نویسندگان
چکیده
T-modulated differential scanning calorimetry measurements on bulk AsxSe12x glasses show that the glass transition temperature Tg(x) variation at x,0.12 is linear with a slope dTg /dx54.1 °C/at.% As, and the nonreversing heat flow, DHnr(x) almost vanishes in the 0.291~1!,x,0.37~1! composition range. These thermal results analyzed by agglomeration theory and constraint theory suggest that in addition to As(Se1/2)3 units, quasitetrahedral Se5As~Se1/2)3 units also serve to crosslink Seq chains at x, 2 5 . The results also suggest that rigidity onsets at rc(1)52.29(1) and the transition to the stressed rigid phase occurs at rc(2)52.37(1), below the chemical threshold at rct52.40 ~or x5 2 5 ).
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