The glass transition, a relaxation phenomenon, sets the low temperature limit to the liquid state. Glassy water that forms only under extreme quenching conditions is unstable against crystallization. Opinions differ on whether the glass transition can be observed at all. Here we measure the dielectric tan(delta for easily glassforming waterlike aqueous solutions, H2O-H2O2 and H2O-N2H4, to characterize the behavior of such systems during passage through their glass transitions. All show unambiguous Tg values of 136-140 K, the value generally assigned to pure water. However, the behavior of epsilon''/epsilon' is quite different from that in amorphous water in the same temperature range. Our findings eliminate "ultraviscous fragile liquid" as a possible description of water between 136 K and crystallization, but leave "ultraviscous strong liquid" a possibility to be considered.

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Complex permittivity measurements were performed on sorbitol, xylitol, and sorbitol-xylitol mixture in the supercooled liquid state in an extremely wide frequency range from 10 microHz to 500 MHz at temperatures near and above the glass transition temperature. We determined detailed behavior of the relaxation parameters such as relaxation frequency and broadening against temperature not only for the alpha process but also for the beta process above the glass transition temperature, to the best of our knowledge, for the first time. Since supercooled liquids are in the quasi-equilibrium state, the behavior of all the relaxation parameters for the beta process can be compared among the polyols as well as those for the alpha process. The relaxation frequencies of the alpha processes follow the Vogel-Fulcher-Tammann manner and the loci in the Arrhenius diagram are different corresponding to the difference of the glass transition temperatures. On the other hand, the relaxation frequencies of the beta processes, which are often called as the Johari-Goldstein processes, follow the Arrhenius-type temperature dependence. The relaxation parameters for the beta process are quite similar among the polyols at temperatures below the alphabeta merging temperature, T(M). However, they show anomalous behavior near T(M), which depends on the molecular size of materials. These results suggest that the origin of the beta process is essentially the same among the polyols.

We report dielectric relaxation studies of aqueous solutions of two water-like molecules, hydrazine and hydrogen peroxide, in the neighborhood of their glass transition temperatures, T g . These solutions behave in a rather simple manner, reminiscent of the diols and diamines of which they are the limiting cases. Their relaxations near T g are more nearly exponential than in most other cases, and they show essentially no secondary relaxations. Supercooled hydrazine solutions are the more stable. At the composition 20 mol % N 2 H 4 , the liquid exhibits precise time-temperature-superposition (TTS) behavior. At higher N 2 H 4 contents, a weak deviation from TTS appears. The temperature dependence of the relaxation time follows the Vogel-Fulcher-Tammann (VFT) equation, and the strength parameter, D, is similar to that of glycerol, a liquid of intermediate fragility.The VFT divergence temperature, T 0 , lies close to the Kauzmann temperature, T K , determined earlier from calorimetric studies implying that the thermodynamic and kinetic measures of fragility are very similar. T g values assessed from T(τ)100s) agree well with observed calorimetric, T g 's. Extrapolation of the relaxation time behavior to pure water would imply a T g for water of 135-140 K; however, the dielectric behavior of amorphous solid water in the temperature range 130-160 K is completely different from that of the solutions showing no sign of the loss peak exhibited by all the solutions. Based on the solution behavior, water controversially must either remain glassy up until the temperature of crystallization or be an almost ideally strong liquid above 136 K. Having shown elsewhere how this implies glassy character up to LDA crystallization and a T g above 160 K, we now examine the implications for water structure reorganization on dissolution of solutes, certain glycols excepted. It appears that the water in these solutions behaves like ice III rather than ice I. † Part of the special issue "Frank H. Stillinger Festschrift".

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Complex permittivity was obtained on glycerol, xylitol, sorbitol and sorbitol-xylitol mixtures in the supercooled liquid state in the frequency range between 10 microHz and 500 MHz at temperatures near and above the glass transition temperature. For all the materials, a dielectric relaxation process was observed in addition to the well-known structural alpha and Johari-Goldstein beta relaxation process [G. P. Johari and M. Goldstein, J. Chem. Phys. 53, 2372 (1970)]. The relaxation time for the new process is always larger than that for the alpha process. The relaxation time shows non-Arrhenius temperature dependence with correlation to the behavior of the alpha process and it depends on the molecular size systematically. The dielectric relaxation strength for the new process shows the effect of thermal history and decreases exponentially with time at a constant temperature. It can be considered that a nonequilibrium dynamics causes the new process.

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