Intermediate range order dynamics – key to understanding of the glass transition

Abstract

Introducing a new experimental approach allowed us to extend the study of the collective dynamics to the length scale of intermediate range order in the model glass former Ca–K–NO 3 (CKN) using time-of-flight (NEAT/BENSC) and spin-echo (InLL/ILL) technique. Our results provide for the first time direct experimental evidence that the β-process is of relaxational nature and corresponds to fast heterogeneous flow of groups of atoms.We did not observe any sign of the sharp singularity of the effective Debye–Waller factor, which could be an indication of the mode coupling theory critical temperature (Gotze, Z. Phys. 60 (1985) 195; Gotze and Sjogren, Rep. Progr. Phys. 55 (1992) 242).