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  • Title: Interdependence of primary and Johari-Goldstein secondary relaxations in glass-forming systems.
    Author: Kessairi K, Capaccioli S, Prevosto D, Lucchesi M, Sharifi S, Rolla PA.
    Journal: J Phys Chem B; 2008 Apr 17; 112(15):4470-3. PubMed ID: 18366219.
    Abstract:
    We report evidence from broadband dielectric spectroscopy that the dynamics of the primary alpha- and secondary Johari-Goldstein (JG) beta-processes are strongly correlated in different glass-forming systems over a wide temperature T and pressure P range, in contrast with the widespread opinion of statistical independence of these processes. The alpha-beta mutual dependence is quantitatively confirmed by (a) the overall superposition of spectra measured at different T-P combinations but with an invariant alpha-relaxation time; (b) the contemporary scaling of the isothermal-pressure and isobaric-temperature dependences of the alpha-and beta-relaxation times as plotted versus the reduced variable Tg(P)/T where Tg is the glass transition temperature. These novel and model-independent evidences indicate the relevance of the JG relaxation phenomenon in glass transition, often overlooked by most current theories.
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