We have investigated two ionic salt systems with different degrees of fragility, Ca0.4K0.6(NO3)(1.4) (CKN) and ZnCl2, by cold-neutron spectroscopy. The spectra were studied in detail around the glass-transition temperatures. Harmonic vibrations dominate the dynamics in both systems below the glass transition. With increasing temperature a strong anharmonic additional intensity was observed in the picosecond range in both systems. The results of our study show correlations between the low-energy excitations and the degree of fragility: harmonic vibrations are better pronounced in less fragile systems, while the anharmonic picosecond dynamics are stronger in fragile glass-forming liquids.
Dynamic correlations around the glass transition in systems with different degrees of fragility / Russina, Olga; Russina, M; Mezei, F; Lechner, R; Pieper, J; Desmedt, A.. - In: APPLIED PHYSICS. A, MATERIALS SCIENCE & PROCESSING. - ISSN 0947-8396. - STAMPA. - 74:S(2002), pp. S1192-S1193. [10.1007/s003390201689]
Dynamic correlations around the glass transition in systems with different degrees of fragility
RUSSINA, OLGA;
2002
Abstract
We have investigated two ionic salt systems with different degrees of fragility, Ca0.4K0.6(NO3)(1.4) (CKN) and ZnCl2, by cold-neutron spectroscopy. The spectra were studied in detail around the glass-transition temperatures. Harmonic vibrations dominate the dynamics in both systems below the glass transition. With increasing temperature a strong anharmonic additional intensity was observed in the picosecond range in both systems. The results of our study show correlations between the low-energy excitations and the degree of fragility: harmonic vibrations are better pronounced in less fragile systems, while the anharmonic picosecond dynamics are stronger in fragile glass-forming liquids.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
